Document:

Indemnification Agreement dated as of July 28, 2003

   EXHIBIT 10.14
  INDEMNIFICATION AGREEMENT

	          This Indemnification Agreement (the “Agreement”) is entered into as of the 28th day of July, 2003, by and
among Sirna Therapeutics, Inc., a Delaware corporation (the “Company”) and the indemnitees listed on the signature pages hereto (each an “Indemnitee” and collectively, the
“Indemnitees”).
 
	  
 	   
 	   
 	   
 	   
 
	  RECITALS
 
	  
 
	          A.     The Company and the Indemnitees recognize the continued difficulty in obtaining liability insurance
for the Company’s directors, officers, employees, controlling persons, agents and fiduciaries, the significant increases in the cost of such insurance and the general reductions in the coverage of such insurance.
 
	   
 	   
 	   
 	   
 	   
 
	          B.     The Company and the Indemnitees further recognize the substantial increase in corporate
litigation in general, subjecting directors, officers, employees, controlling persons, agents and fiduciaries to expensive litigation risks at the same time as the availability and coverage of liability insurance has been severely
limited.
 
	   
 	   
 	   
 
	         C.     The Indemnitees do not regard the prior protection available as adequate under the circumstances,
and the Indemnitees and other directors, officers, employees, controlling persons, agents and fiduciaries of the Company are not willing to serve in such capacities without additional protection, so the Company and the Indemnitees desire to enter
into this Agreement.
 
	   
 	   
 	   
 
	          D.     The Company (i) desires to attract and retain the involvement of highly qualified groups, such as
the Indemnitees, to serve the Company and, in part, to induce each Indemnitee to be involved with the Company and (ii) wishes to provide for the indemnification and advancing of expenses to each Indemnitee to the maximum extent permitted by
law.
 
	   
 	   
 	   
 
	          E.     In view of the considerations set forth above, the Company desires that each Indemnitee be
indemnified by the Company as set forth herein.
 
	   
 	   
 	   
 
	  
 	   
 	  NOW, THEREFORE, the Company and each Indemnitee hereby agrees as follows:
 
	   
 	   
 	   
 	   
 	   
 
	   
 	   
 	  1.
 	  Indemnification.
 
	   
 	   
 	   
 	   
 	   
 
	                            a.     Indemnification of
Expenses.  The Company shall indemnify and hold harmless each Indemnitee (including, without limitation, its respective directors, officers, partners, employees, agents and spouses) and each person who controls any of them or who may be
liable within the meaning of Section 15 of the Securities Act of 1933, as amended (the “Securities Act”), or Section 20 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) to the
fullest extent permitted by law if such Indemnitee was or is or becomes a party to or witness or other participant in, or is threatened to be made a party to or witness or other participant in, any threatened, pending or completed action, suit,
proceeding or alternative dispute resolution mechanism, or any hearing, inquiry or investigation that such Indemnitee reasonably believes might lead to the institution of any such action, suit, proceeding or alternative dispute resolution mechanism,
whether civil, criminal, administrative, investigative or other (hereinafter a “Claim”) by reason of (or arising in part out of) any event or occurrence related to the fact that such Indemnitee is or was a director, officer,
employee, controlling person, agent or fiduciary of the Company, or any subsidiary of the Company, or is or was serving at the request of the Company as a director, officer, employee, controlling person, agent or fiduciary of another

	  corporation, partnership, joint venture, trust or other enterprise, or by reason of any action or inaction on the part of such Indemnitee while serving in such capacity
including, without limitation, any and all losses, claims, damages, expenses and liabilities, joint or several (including, without limitation, any investigation, legal and other expenses incurred in connection with, and any amount paid in settlement
of, any action, suit, proceeding or any claim asserted) under the Securities Act, the Exchange Act or other federal or state statutory law or regulation, at common law or otherwise, which relate directly or indirectly to the registration, purchase,
sale or ownership of any securities of the Company or to any fiduciary obligation owed with respect thereto (hereinafter an “Indemnification Event”) against any and all expenses (including, without limitation, reasonable
attorneys’ fees and all other reasonable costs, expenses and obligations incurred in connection with investigating, defending a witness in or participating in (including, without limitation, on appeal), or preparing to defend, be a witness in
or participate in, any such action, suit, proceeding, alternative dispute resolution mechanism, hearing, inquiry or investigation), judgments, fines, penalties and amounts paid in settlement (if such settlement is approved in advance by the Company,
which approval shall not be unreasonably withheld) of such Claim and any federal, state, local or foreign taxes imposed on such Indemnitee as a result of the actual or deemed receipt of any payments under this Agreement (collectively, hereinafter
“Expenses”), including, without limitation, all interest, assessments and other charges paid or payable in connection with or in respect of such Expenses.  Such payment of allowed Expenses shall be made by the Company as
soon as practicable but in any event no later than five (5) days after written demand by the Indemnitee therefor is presented to the Company.
 
	  
 
	                            b.     Reviewing Party. 
Notwithstanding the foregoing, (i) the obligations of the Company under Section 1(a) shall be subject to the condition that the Reviewing Party (as described in Section 10(e) hereof) shall not have determined (in a written opinion, in any case in
which the Independent Legal Counsel referred to in Section 10(d) hereof is involved) that an Indemnitee would not be permitted to be indemnified under applicable law, and (ii) each Indemnitee acknowledges and agrees that the obligation of the
Company to make an advance payment of Expenses to an Indemnitee pursuant to Section 2(a) (an “Expense Advance”) shall be subject to the condition that, if, when and to the extent that the Reviewing Party determines that an
Indemnitee would not be permitted to be so indemnified under applicable law, the Company shall be entitled to be reimbursed by such Indemnitee (who hereby agrees to reimburse the Company) for all such amounts theretofore paid; provided,
however, that if such Indemnitee has commenced or thereafter commences legal proceedings in a court of competent jurisdiction to secure a determination that such Indemnitee should be indemnified under applicable law, any determination made by
the Reviewing Party that such Indemnitee would not be permitted to be indemnified under applicable law shall not be binding and such Indemnitee shall not be required to reimburse the Company for any Expense Advance until a final judicial
determination is made with respect thereto (as to which all rights of appeal therefrom have been exhausted or lapsed).  An Indemnitee’s obligation to reimburse the Company for any Expense Advance shall be unsecured and no interest shall be
charged thereon if such reimbursement is made within thirty (30) days of such final judicial determination, unless otherwise required by the court.  If there has not been a Change in Control (as defined in Section 10(c) hereof), the Reviewing
Party shall be selected by the Board of Directors, and if there has been such a Change in Control (other than a Change in Control that has been approved by a majority of the Company’s Board of Directors who were directors immediately prior to
such Change in Control), the Reviewing Party shall be the Independent Legal Counsel referred to in Section 10(d) hereof.  If there has been no determination by the Reviewing Party or if the Reviewing Party determines that an Indemnitee
substantively would not be permitted to be indemnified in whole or in part under applicable law, the Indemnitee shall have the right to commence litigation seeking an initial determination by the court or challenging any such determination by the
Reviewing Party or any aspect thereof, including, without limitation, the legal or factual bases therefor, and the Company hereby consents to service of process and to appear in any such proceeding.  Any determination by the Reviewing Party
otherwise shall be conclusive and binding on the Company and such Indemnitee.
 

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	                            c.     Contribution.  If the
indemnification provided for in Section 1(a) above for any reason is held by a court of competent jurisdiction to be unavailable to an Indemnitee in respect of any losses, claims, damages, expenses or liabilities referred to therein, then the
Company, in lieu of indemnifying such Indemnitee thereunder, shall contribute to the amount paid or payable by such Indemnitee as a result of such losses, claims, damages, expenses or liabilities (i) in such proportion as is appropriate to reflect
the relative benefits received by the Company and the Indemnitees, or (ii) if the allocation provided by clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to
in clause (i) above but also the relative fault of the Company and the Indemnitees in connection with the action or inaction that resulted in such losses, claims, damages, expenses or liabilities, as well as any other relevant equitable
considerations.  In connection with the registration of the Company’s securities, the relative benefits received by the Company and the Indemnitees shall be deemed to be in the same respective proportions that the net proceeds from the
offering (before deducting expenses) received by the Company and the Indemnitees, in each case as set forth in the table on the cover page of the applicable prospectus, bear to the aggregate public offering price of the securities so offered. 
The relative fault of the Company and the Indemnitees shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to
information supplied by the Company or the Indemnitees and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.
 
	  
 
	                   The Company and the Indemnitees agree that it would not be just and equitable if
contribution pursuant to this Section 1(c) were determined by pro rata or per capita allocation or by any other method of allocation that does not take account of the equitable considerations referred to in the immediately preceding paragraph. 
In connection with the registration of the Company’s securities, in no event shall an Indemnitee be required to contribute any amount under this Section 1(c) in excess of the lesser of (i) that proportion of the total of such losses, claims,
damages or liabilities that are indemnified against, equal to the proportion of the total securities sold under such registration statement that are being sold by such Indemnitee or (ii) the proceeds received by such Indemnitee from its sale of
securities under such registration statement.  No person found guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not found guilty of such
fraudulent misrepresentation.
 
	   
 
	                             d.     Survival Regardless of
Investigation.  The indemnification and contribution provided for in this Section 1 will remain in full force and effect regardless of any investigation made by or on behalf of the Indemnitees or any officer, director, employee, agent or
controlling person of the Indemnitees.
 
	   
 
	                             e.     Change in Control. 
The Company agrees that if there is a Change in Control of the Company (other than a Change in Control that has been approved by a majority of the Company’s Board of Directors who were directors immediately prior to such Change in Control)
then, with respect to all matters thereafter arising concerning the rights of the Indemnitees to payments of Expenses under this Agreement or any other agreement or under the Company’s Certificate of Incorporation or Bylaws as now or hereafter
in effect, Independent Legal Counsel (as defined in Section 10(d) hereof) shall be selected by the Indemnitees and approved by the Company (which approval shall not be unreasonably withheld).  Such counsel, among other things, shall render its
written opinion to the Company and the Indemnitees as to whether and to what extent the Indemnitees would be permitted to be indemnified under applicable law.  The Company agrees to abide by such opinion and to pay the reasonable fees of the
Independent Legal Counsel referred to above and to fully indemnify such counsel against any and all expenses (including, without limitation, reasonable attorneys’ fees), claims, liabilities and damages arising out of or relating to this
Agreement or its engagement pursuant hereto.
 

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	                              f.     Mandatory Payment of
Expenses.  Notwithstanding any other provision of this Agreement, to the extent that the Indemnitees have been successful on the merits or otherwise, including, without limitation, the dismissal of an action without prejudice, in the
defense of any action, suit, proceeding, inquiry or investigation referred to in Section 1(a) hereof or in the defense of any claim, issue or matter therein, each Indemnitee shall be indemnified against all Expenses incurred by such Indemnitee
in connection herewith.
 
	   
 
	   
 	   
 	  2.
 	  Expenses; Indemnification Procedure.
 
	   
 	   
 	   
 	   
 
	                           a.     Advancement of Expenses. 
The Company shall advance all Expenses incurred by the Indemnitees.  The advances to be made hereunder shall be paid by the Company to the Indemnitees as soon as practicable but in any event no later than five (5) days after written demand by
such Indemnitees therefor to the Company.
 
	   
 
	                            b.     Notice/Cooperation by the
Indemnitees.  Each Indemnitee shall give the Company notice in writing as soon as practicable of any Claim made against such Indemnitee for which indemnification will or could be sought under this Agreement.  Notice to the Company
shall be directed to the Company’s Chief Executive Officer at the Company’s address (or such other address as the Company shall designate in writing to the Indemnitees).
 
	   
 
	                            c.     No Presumptions; Burden of
Proof.  For purposes of this Agreement, the termination of any Claim by judgment, order, settlement (whether with or without court approval) or conviction, or upon a plea of nolo contendere, or its equivalent, shall not create a presumption
that the Indemnitees did not meet any particular standard of conduct or have any particular belief or that a court has determined that indemnification is not permitted by applicable law.  In addition, neither the failure of the Reviewing Party
to have made a determination as to whether an Indemnitee has met any particular standard of conduct or had any particular belief, nor an actual determination by the Reviewing Party that an Indemnitee has not met such standard of conduct or did not
have such belief, prior to the commencement of legal proceedings by such Indemnitee to secure a judicial determination that such Indemnitee should be indemnified under applicable law, shall be a defense to an Indemnitee’s claim or create a
presumption that such Indemnitee has not met any particular standard of conduct or did not have any particular belief.  In connection with any determination by the Reviewing Party or otherwise as to whether an Indemnitee is entitled to be
indemnified hereunder, the burden of proof shall be on the Company to establish that an Indemnitee is not so entitled.
 
	  
 
	                            d.     Notice to Insurers.  If,
at the time of the receipt by the Company of a notice of a Claim pursuant to Section 2(b) hereof, the Company has liability insurance in effect that may cover such Claim, the Company shall give prompt notice of the commencement of such Claim to the
insurers in accordance with the procedures set forth in each of the policies.  The Company shall thereafter take all necessary or desirable action to cause such insurers to pay, on behalf of the Indemnitees, all amounts payable as a result of
such action, suit, proceeding, inquiry or investigation in accordance with the terms of such policies.
 
	   
 
	                            e.     Selection of Counsel.  In
the event the Company shall be obligated hereunder to pay the Expenses of any Claim, the Company shall be entitled to assume the defense of such Claim, with counsel approved by the applicable Indemnitee, upon the delivery to such Indemnitee of
written notice of its election to do so.  After delivery of such notice, approval of such counsel by the Indemnitee and the retention of such counsel by the Company, the Company will not be liable to such Indemnitee under this Agreement for any
fees of counsel subsequently incurred by such Indemnitee with respect to the same Claim; provided that, (i) the Indemnitee shall have the right to employ such Indemnitee’s counsel in any such Claim at the Indemnitee’s expense and
(ii) if (A) the employment of
 

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	  counsel by the Indemnitee has been previously authorized by the Company, (B) such Indemnitee shall have reasonably concluded that there is a conflict of interest between the
Company and such Indemnitee in the conduct of any such defense, or (C) the Company shall not continue to retain such counsel to defend such Claim, then the fees and expenses of the Indemnitee’s counsel shall be at the expense of the
Company.  The Company shall have the right to conduct such defense as it sees fit in its sole discretion, including, without limitation, the right to settle any claim against any Indemnitee without the consent of such Indemnitee.

	   
 
	                   3.     Additional Indemnification Rights; Nonexclusivity.
 
	   
 	   
 	   
 	   
 
	                           a.     Scope.  The Company hereby
agrees to indemnify the Indemnitees to the fullest extent permitted by law, even if such indemnification is not specifically authorized by the other provisions of this Agreement, the Company’s Certificate of Incorporation, the Company’s
Bylaws or by statute.  In the event of any change after the date of this Agreement in any applicable law, statute or rule that expands the right of a Delaware corporation to indemnify a member of its Board of Directors or an officer, employee,
controlling person, agent or fiduciary, it is the intent of the parties hereto that the Indemnitees shall enjoy by this Agreement the greater benefits afforded by such change.  In the event of any change after the date of this Agreement in any
applicable law, statute or rule that narrows the right of a Delaware corporation to indemnify a member of its Board of Directors or an officer, employee, agent or fiduciary, such change, to the extent not otherwise required by such law, statute or
rule to be applied to this Agreement, shall have no effect on this Agreement or the parties’ rights and obligations hereunder except as set forth in Section 8(a) hereof.
 
	   
 
	                            b.     Nonexclusivity.  The
indemnification provided by this Agreement shall be in addition to any rights to which the Indemnitees may be entitled under the Company’s Certificate of Incorporation, its Bylaws, any agreement, any vote of stockholders or disinterested
directors, the Delaware General Corporation Law, or otherwise. The indemnification provided under this Agreement shall continue as to each Indemnitee for any action such Indemnitee took or did not take while serving in an indemnified capacity even
though the Indemnitee may have ceased to serve in such capacity.
 
	  
 
	                   4.     No Duplication of Payments. 
The Company shall not be liable under this Agreement to make any payment in connection with any Claim made against any Indemnitee to the extent such Indemnitee has otherwise actually received payment (under any insurance policy, Certificate of
Incorporation, Bylaw or otherwise) of the amounts otherwise indemnifiable hereunder.
 
	   
 
	                   5.     Partial Indemnification.  If
any Indemnitee is entitled under any provision of this Agreement to indemnification by the Company for any portion of Expenses incurred in connection with any Claim, but not, however, for all of the total amount thereof, the Company shall
nevertheless indemnify such Indemnitee for the portion of such Expenses to which such Indemnitee is entitled.
 
	   
 
	                   6.     Mutual Acknowledgement.  The
Company and each Indemnitee acknowledge that in certain instances, Federal law or applicable public policy may prohibit the Company from indemnifying its directors, officers, employees, controlling persons, agents or fiduciaries under this Agreement
or otherwise.  Each Indemnitee understands and acknowledges that the Company has undertaken or may be required in the future to undertake with the Securities and Exchange Commission to submit the question of indemnification to a court in
certain circumstances for a determination of the Company’s rights under public policy to indemnify the Indemnitees.
 
	  
 
	                   7.     Liability Insurance.  To the
extent the Company maintains liability insurance applicable to directors, officers, employees, control persons, agents or fiduciaries, each of the Indemnitees shall be covered by such policies in such a manner as to provide the Indemnitees the same
rights and
 

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	  benefits as are accorded to the most favorably insured of the Company’s directors, if such Indemnitee is a director, or of the Company’s officers, if such Indemnitee
is not a director of the Company but is an officer; or of the Company’s key employees, controlling persons, agents or fiduciaries, if such Indemnitee is not an officer or director but is a key employee, agent, control person, or
fiduciary.
 
	   
 	   
 	   
 	   
 	   
 
	                  8.     Exceptions.  Any other provision
herein to the contrary notwithstanding, the Company shall not be obligated pursuant to the terms of this Agreement:
 
	   
 
	                            a.     Claims Initiated by an
Indemnitee.  To indemnify or advance expenses to any Indemnitee with respect to Claims initiated or brought voluntarily by such Indemnitee and not by way of defense, except (i) with respect to actions or proceedings to establish or enforce
a right to indemnify under this Agreement or any other agreement or insurance policy or under the Company’s Certificate of Incorporation or Bylaws now or hereafter in effect relating to Claims for Indemnifiable Events, (ii) in specific cases if
the Board of Directors has approved the initiation or bringing of such Claim, or (iii) as otherwise required under Section 145 of the Delaware General Corporation Law, regardless of whether such Indemnitee ultimately is determined to be entitled to
such indemnification, advance expense payment or insurance recovery, as the case may be; or
 
	   
 
	                            b.     Claims Under Section
16(b).  To indemnify any Indemnitee for expenses and the payment of profits arising from the purchase and sale by such Indemnitee of securities in violation of Section 16(b) of the Exchange Act or any similar successor statute;
or
 
	  
 
	                            c.     Claims Excluded Under Section 145
of the Delaware General Corporation Law.  To indemnify any Indemnitee if indemnification is expressly prohibited by law, subject to the right of the Indemnitee to challenge such determination pursuant to Section 1(b).
 
	   
 
	                            d.     Claims Resulting from Willful
Misconduct or Fraud.  To indemnify or advance Expenses to any Indemnitee with respect to Claims resulting from such Indemnitee’s willful misconduct or fraud on the part of the Indemnitee.
 
	   
 
	                   9.     Period of Limitations.  No
legal action shall be brought and no cause of action shall be asserted by or in the right of the Company against any Indemnitee or any Indemnitee’s estate, spouse, heirs, executors or personal or legal representatives after the expiration of
five (5) years from the date of accrual of such cause of action, and any claim or cause of action of the Company shall be extinguished and deemed released unless asserted by the timely filing of a legal action within such five (5)-year period;
provided, however, that if any shorter period of limitations is otherwise applicable to any such cause of action, such shorter period shall govern.
 
	  
 
	                   10.    Construction of Certain
Phrases.
 
	   
 
	                            a.     For purposes of this Agreement,
references to the “Company” shall include, in addition to the resulting corporation, any constituent corporation (including, without limitation, any constituent of a constituent) absorbed in a consolidation or merger that, if
its separate existence had continued, would have had power and authority to indemnify its directors, officers, employees, agents or fiduciaries, so that if an Indemnitee is or was a director, officer, employee, agent, control person, or fiduciary of
such constituent corporation, or is or was serving at the request of such constituent corporation as a director, officer, employee, control person, agent or fiduciary of another corporation, partnership, joint venture, employee benefit plan, trust
or other enterprise, each Indemnitee shall stand in the same position under the provisions of this Agreement with respect to the resulting or surviving corporation as each Indemnitee would have with respect to such constituent corporation if its
separate existence had continued.
 

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	                           b.     For purposes of this Agreement,
references to “other enterprises” shall include, without limitation, employee benefit plans; references to “fines” shall include, without limitation, any excise taxes assessed on any Indemnitee with
respect to an employee benefit plan; and references to “serving at the request of the Company” shall include any service as a director, officer, employee, agent or fiduciary of the Company that imposes duties on, or involves
services by, such director, officer, employee, agent or fiduciary with respect to an employee benefit plan, its participants or its beneficiaries; and if any Indemnitee acted in good faith and in a manner such Indemnitee reasonably believed to be in
the interest of the participants and beneficiaries of an employee benefit plan, such Indemnitee shall be deemed to have acted in a manner “not opposed to the best interests of the Company” as referred to in this
Agreement.
 
	   
 
	                            c.     For purposes of this Agreement a
“Change in Control” shall be deemed to have occurred if (i) any “person” (as such term is used in Sections 13(d)(3) and 14(d)(2) of the Exchange Act), other than a trustee or other fiduciary holding securities under
an employee benefit plan of the Company or a corporation owned directly or indirectly by the stockholders of the Company in substantially the same proportions as their ownership of stock of the Company, (A) who is or becomes the beneficial owner,
directly or indirectly, of securities of the Company representing ten percent (10%) or more of the combined voting power of the Company’s then outstanding Voting Securities (as defined in Section 10(f) hereof), increases his beneficial
ownership of such securities by five percent (5%) or more over the percentage so owned by such person, or (B) becomes the “beneficial owner” (as defined in Rule 13d-3 under said Exchange Act), directly or indirectly, of securities of
the Company representing more than twenty percent (20%) of the total voting power represented by the Company’s then outstanding Voting Securities, (ii) during any period of two (2) consecutive years, individuals who at the beginning of such
period constitute the Board of Directors of the Company and any new director whose election by the Board of Directors or nomination for election by the Company’s stockholders was approved by a vote of at least two-thirds (2/3) of the directors
then still in office who either were directors at the beginning of the period or whose election or nomination for election was previously so approved, cease for any reason to constitute a majority thereof, or (iii) the stockholders of the Company
approve a merger or consolidation of the Company with any other corporation other than a merger or consolidation that would result in the Voting Securities of the Company outstanding immediately prior thereto continuing to represent (either by
remaining outstanding or by being converted into Voting Securities of the surviving entity) at least eighty percent (80%) of the total voting power represented by the Voting Securities of the Company or such surviving entity outstanding immediately
after such merger or consolidation, or the stockholders of the Company approve a plan of complete liquidation of the Company or an agreement for the sale or disposition by the Company of (in one transaction or a series of transactions) all or
substantially all of the Company’s assets.
 
	  
 
	                            d.     For purposes of this Agreement,
“Independent Legal Counsel” shall mean an attorney or firm of attorneys, selected in accordance with the provisions of Section 2(e) hereof, who shall not have otherwise performed services for the Company or any
Indemnitee within the last three (3) years (other than with respect to matters concerning the right of any Indemnitee under this Agreement, or of other indemnitees under similar indemnity agreements).
 
	   
 
	                            e.     For purposes of this Agreement, a
“Reviewing Party” shall mean any appropriate person or body consisting of a member or members of the Company’s Board of Directors or any other person or body appointed by the Board of Directors who is not a party to the
particular Claim for which the Indemnitees are seeking indemnification, or Independent Legal Counsel.
 
	   
 
	                            f.     For purposes of this Agreement,
“Voting Securities” shall mean any securities of the Company that vote generally in the election of directors.
 

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	                   11.    Amendment and Termination. Any term
hereof may be amended (either generally or in a particular instance and either retroactively or prospectively) only with the written consent of (a) the Company; and (b) each Indemnitee, if any, adversely affected by such amendment.  Any
amendment so effected shall be binding upon the Company and all Indemnitees and all of their respective successors and assigns whether or not such person or entity entered into or approved such amendment or waiver.  The observance of any term
hereof may be waived by a party with respect to its own interests (either generally or in a particular instance and either retroactively or prospectively) only with the written consent of the party so waiving the observance of such term.  In no
event shall such waiver of any rights hereunder constitute the waiver of such rights in any future instance unless the waiver so specifies in writing. Notwithstanding anything to the contrary in this Agreement, the Company may add additional
Indemnitees at any time to this Agreement without the consent of any other Indemnitee.
 
	   
 
	                   12.    Attorneys’ Fees.  In the event
that any action is instituted by an Indemnitee under this Agreement or under any liability insurance policies maintained by the Company to enforce or interpret any of the terms hereof or thereof, any Indemnitee shall be entitled to be paid all
Expenses incurred by such Indemnitee with respect to such action, regardless of whether such Indemnitee is ultimately successful in such action, and shall be entitled to the advancement of Expenses with respect to such action, unless, as a part of
such action, a court of competent jurisdiction over such action determines that each of the material assertions made by such Indemnitee as a basis for such action was not made in good faith or was frivolous.  In the event of an action
instituted by or in the name of the Company under this Agreement to enforce or interpret any of the terms of this Agreement, the Indemnitee shall be entitled to be paid all Expenses incurred by such Indemnitee in defense of such action (including,
without limitation, costs and expenses incurred with respect to such Indemnitee’s counterclaims and cross-claims made in such action), and shall be entitled to the advancement of Expenses with respect to such action, unless, as a part of such
action, a court having jurisdiction over such action determines that each of such Indemnitee’s material defenses to such action was made in bad faith or was frivolous.
 
	  
 
	                   13.    Binding Effect.  This Agreement
shall be binding upon and inure to the benefit of and be enforceable by the parties hereto and their respective successors, assigns, including, without limitation, any direct or indirect successor by purchase, merger, consolidation or otherwise to
all or substantially all of the business and/or assets of the Company, spouses, heirs, and personal and legal representatives.
 
	   
 
	                   14.    Choice of Law.  This Agreement shall
be governed by and its provisions construed and enforced in accordance with the laws of the State of Delaware, as applied to contracts between Delaware residents, entered into and to be performed entirely within the State of Delaware, without regard
to the conflict of laws principles thereof.
 
	   
 
	                   15.    Consent to Jurisdiction.  The
Company and each Indemnitee each hereby irrevocably consents to the jurisdiction of the courts of the State of Delaware for all purposes in connection with any action or proceeding that arises out of or relates to this Agreement and agree that any
action instituted under this Agreement shall be commenced, prosecuted and continued only in the Court of Chancery of the State of Delaware in and for New Castle County, which shall be the exclusive and only proper forum for adjudicating such a
claim.
 
	  
 
	                   16.    Corporate Authority.  The Board of
Directors of the Company and its stockholders have approved the terms of this Agreement.
 
	   
 
	                   17.    Counterparts.  This Agreement may be
executed in one (1) or more counterparts, each of which shall constitute an original.
 

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	                   18.    Integration and Entire Agreement. 
Subject to Section 3(b), this Agreement sets forth the entire understanding between the parties hereto and supersedes and merges all previous written and oral negotiations, commitments, understandings and agreements relating to the subject matter
hereof between the parties hereto.
 
	   
 
	                  19.    No Construction as Employment
Agreement.  Nothing contained in this Agreement shall be construed as giving any Indemnitee any right to be retained in the employ of the Company or any of its subsidiaries.
 
	   
 
	                   20.    Notice.  All notices and other
communications required or permitted hereunder shall be in writing, shall be effective when given, and shall in any event be deemed to be given (i) two (2) days after deposit with the U.S. Postal Service or other applicable postal service, if
delivered by first class mail, postage prepaid, (ii) upon delivery, if delivered by hand, (iii) one (1) business day after the business day of deposit with Federal Express or similar overnight courier, freight prepaid, or (iv) one (1) day after the
business day of delivery by facsimile transmission, if deliverable by facsimile transmission, with copy by first class mail, postage prepaid, and shall be addressed if to the Indemnitees, at each Indemnitee’s address as set forth beneath the
Indemnitees’ signatures to this Agreement and if to the Company at the address of its principal corporate offices (Attention:  Secretary) or at such other address as such party may designate by ten (10) days’ advance written notice to
the other party hereto.
 
	   
 
	                   21.    Severability.  The provisions of
this Agreement shall be severable in the event that any of the provisions hereof (including, without limitation, any provision within a single section, paragraph or sentence) are held by a court of competent jurisdiction to be invalid, void or
otherwise unenforceable, and the remaining provisions shall remain enforceable to the fullest extent permitted by law.  Furthermore, to the fullest extent possible, the provisions of this Agreement (including, without limitation, each portion
of this Agreement containing any provision held to be invalid, void or otherwise unenforceable, that is not itself invalid, void or unenforceable) shall be construed so as to give effect to the intent manifested by the provision held invalid,
illegal or unenforceable.
 
	  
 
	                   22.    Subrogation.  In the event of
payment under this Agreement, the Company shall be subrogated to the extent of such payment to all of the rights of recovery of an Indemnitee who shall execute all documents required and shall do all acts that may be necessary to secure such rights
and to enable the Company effectively to bring suit to enforce such rights.
 
	   
 
	                   23.    Successors and Assigns.  The Company
shall require and cause any successor (whether direct or indirect by purchase, merger, consolidation or otherwise) to all, substantially all, or a substantial part, of the business and/or assets of the Company, by written agreement in form and
substance satisfactory to each Indemnitee, expressly to assume and agree to perform this Agreement in the same manner and to the same extent that the Company would be required to perform if no such succession had taken place.  This Agreement
shall continue in effect with respect to Claims relating to Indemnifiable Events regardless of whether any Indemnitee continues to serve as a director, officer, employee, agent, controlling person, or fiduciary of the Company or of any other
enterprise, including, without limitation, subsidiaries of the Company, at the Company’s request.
 

  [Signature Pages Follow]
  9

                       IN WITNESS WHEREOF, the parties hereto have executed
this Agreement on and as of the day and year first written above.

	   
 	  SIRNA THERAPEUTICS, INC.:
 	   
 
	   
 	   
 	   
 	   
 
	   
 	  By:
 	  /s/ HOWARD W. ROBIN
 	   
 
	   
 	   
 	 
 	   
 
	   
 	  Name:
 	  Howard W. Robin
 	   
 
	  
 	  Title:
 	  President & CEO
 	   
 
	   
 	  Address:
 	  2950 Wilderness Place
 Boulder, Colorado 80301
 	   
 
	   
 	   
 	   
 	   
 
	   
 	  INDEMNITEE:
 	   
 
	   
 	   
 	   
 
	   
 	   
 	  /s/ R. SCOTT GREER
 	   
 
	  
 	   
 	 
 	   
 
	   
 	   
 	  R. Scott Greer
 	   
 

  SIGNATURE PAGE TO INDEMNIFICATION AGREEMENT<PAGE>

                                                                   Exhibit 10.33

Portions of this exhibit were omitted and filed separately with the Secretary of
the Commission pursuant to an application for confidential treatment filed with
the Commission pursuant to Rule 24b-2 under the Securities Exchange Act of 1934.
Such portions are marked by a series of asterisks.

                           FIRST AMENDED AND RESTATED
                       COLLABORATION AND LICENSE AGREEMENT

                                 by and between

                                      WYETH

                                       and

                             VIROPHARMA INCORPORATED

                        Effective as of December 9, 1999

                                       And

                            Restated on June 26, 2003

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                            Page
                                                                            ----
<S>                                                                         <C>
1.   DEFINITIONS ......................................................        1

     1.1    "Acquiring Entity" ........................................        1
     1.2    "Active Collaboration Target" .............................        1
     1.3    "Active Compound" .........................................        2
     1.4    "Affiliate(s)" ............................................        2
     1.5    "Wyeth Chemical Library" ..................................        5
     1.6    "Wyeth Know-How" ..........................................        5
     1.7    "Wyeth Patent Rights" .....................................        5
     1.8    "Wyeth Technology" ........................................        5
     1.9    "Wyeth Territory" .........................................        5
     1.10   "Annual Commercialization Plan and Budget" ................        6
     1.11   "Annual Development Plan and Budget" ......................        6
     1.12   "Assay and Screening Technology" ..........................        6
     1.13   "Assigned Sales Force Effort" .............................        6
     1.14   "Baseline Allocation of Net Profits" ......................        6
     1.15   "Biomolecule" .............................................        6
     1.16   "Calendar Quarter" ........................................        6
     1.17   "Change of Control" .......................................        6
     1.18   "Class A Product" .........................................        6
     1.19   "Class B Product" .........................................        6
     1.20   "Collaboration Inventions" ................................        6
     1.21   "Collaboration Know-How" ..................................        7
     1.22   "Collaboration Patent Rights" .............................        7
     1.23   "Collaboration Target" ....................................        7
     1.24   "Collaboration Technology" ................................        7
     1.25   "Commercialization" .......................................        7
     1.26   "Commercially Reasonable Efforts" .........................        7
     1.27   "Compound" ................................................        7
     1.28   "Confidential Information" ................................        8
     1.29   "Control" or "Controlled" .................................        8
     1.30   "Copromotion Territory" ...................................        8
     1.31   "Copromotion Territory Commercialization Plan" ............        8
     1.32   "Copyright" ...............................................        8
     1.33   "Cost of Goods Manufactured for Sale" .....................        8
     1.34   "Derivative" ..............................................        8
     1.35   "Detail" ..................................................        8
     1.36   "Development" .............................................        9
     1.37   "Development Candidate" ...................................        9
     1.38   "Development Expenses" ....................................        9
     1.39   "Development Phase" .......................................        9
     1.40   "Effective Date" ..........................................        9
     1.41   "Executive Steering Committee" or "ESC" ...................        9
     1.42   "Extra Effort" ............................................        9
     1.43   "Extra Effort Expense" ....................................        9
     1.44   "FDA" .....................................................        9
     1.45   "FD&C Act" ................................................        9
     1.46   "Field" ...................................................        9
     1.47   "First Commercial Sale" ...................................       10
     1.48   "FTE" .....................................................       10
</TABLE>

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June 26, 2003      Restated & Amended Collaboration Agreement             Page i

<PAGE>

<TABLE>
     <S>                                                                    <C>
     1.49   "Full Royalty Rate Period" ................................     10
     1.50   "Fully-Absorbed Standard Cost" ............................     10
     1.51   "Global Development Plan" .................................     10
     1.52   "Good Clinical Practice" or "GCP" .........................     11
     1.53   "Good Laboratory Practice" or "GLP" .......................     11
     1.54   "HCV" .....................................................     11
     1.55   "Hit" .....................................................     11
     1.56   "Incremental Sales Force Effort" ..........................     11
     1.57   "Incremental Sales Force Effort Expense" ..................     11
     1.58   "IND" .....................................................     11
     1.59   "Initial Term of the Screening Phase" .....................     11
     1.60   "Invention" ...............................................     11
     1.61   "Joint Steering Committee" or "JSC" .......................     12
     1.62   "Know-How" ................................................     12
     1.63   "Lapse Quarter" ...........................................     12
     1.64   "Lapse Year" ..............................................     12
     1.65   "Lead Compound" ...........................................     12
     1.66   "Major European Country" ..................................     12
     1.67   "Marketing Account" .......................................     12
     1.68   "Marketing Steering Committee" or "MSC" ...................     12
     1.69   "NDA" .....................................................     12
     1.70   "Net Profits" .............................................     12
     1.71   "Net Sales" ...............................................     13
     1.72   "Non-Collaboration Invention" .............................     14
     1.73   "Option Period" ...........................................     14
     1.74   "Patent Rights" ...........................................     14
     1.75   "Penalty Year" ............................................     14
     1.76   "Phase I Clinical Study" ..................................     14
     1.77   "Phase II Clinical Study" .................................     15
     1.78   "Phase III Clinical Study" ................................     15
     1.79   "Post Approval Research and Regulatory Expenses" ..........     15
     1.80   "Pre-Development Expenses" ................................     15
     1.81   "Pre-Marketing Expenses" ..................................     15
     1.82   "Pre-Marketing Expense Shortfall" .........................     15
     1.83   "Prior Invention" .........................................     15
     1.84   "Product" .................................................     16
     1.85   "Promotion" ...............................................     16
     1.86   "R&D Account" .............................................     16
     1.87   "R&D Reimbursement Account" ...............................     16
     1.88   "R&D Shortfall" ...........................................     16
     1.89   "Reduced Royalty Rate Period" .............................     16
     1.90   "Regulatory Approval" .....................................     16
     1.91   "Regulatory Authority" ....................................     16
     1.92   "Research" ................................................     16
     1.93   "Research Phase" ..........................................     17
     1.94   "Research Program" ........................................     17
     1.95   "Sales and Marketing Expenses" ............................     17
     1.96   "Sample" ..................................................     17
     1.97   "Sample Receipt Forms" ....................................     17
     1.98   "Screening" ...............................................     17
     1.99   "Screening Phase" .........................................     18
     1.100  "Screening Phase Tail" ....................................     18
     1.101  "Small Molecule" ..........................................     18
     1.102  "Surviving Entity" ........................................     18
     1.103  "Tail Compound" ...........................................     18
     1.104  "Target" ..................................................     18
</TABLE>

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June 26, 2003      Restated & Amended Collaboration Agreement            Page ii

<PAGE>

<TABLE>
<S>                                                                             <C>
     1.105  "Target Market" ..............................................      18
     1.106  "Target Physician" ...........................................      18
     1.107  "Term of the Screening Phase" ................................      18
     1.108  "Third Part(y/ies)" ..........................................      18
     1.109  "Third Party License Fee" ....................................      18
     1.110  "Trademark" ..................................................      19
     1.111  "Valid Claim" ................................................      19
     1.112  "ViroPharma Chemical Library" ................................      19
     1.113  "ViroPharma Know-How" ........................................      19
     1.114  "ViroPharma Patent Rights" ...................................      19
     1.115  "ViroPharma Technology" ......................................      19

2.   LICENSES ............................................................      19

     2.1    Licenses to Wyeth ............................................      20
     2.2    Licenses to ViroPharma .......................................      20
     2.3    Sublicensing to Third Party Contractors ......................      21
     2.4    Dropped Compounds ............................................      21
     2.5    Direct Licenses to Party Affiliates ..........................      21
     2.6    Exclusive Working Relationship ...............................      22
            2.6.1  Collaboration Targets .................................      22
            2.6.2  Other Targets .........................................      23
            2.6.3  Limitations ...........................................      23
     2.7    Right of Reference ...........................................      23

3.   MANAGEMENT OF COLLABORATION .........................................      24

     3.1    Joint Steering Committee .....................................      24
            3.1.1  Formation; Membership .................................      24
            3.1.2  Chairperson; Secretary ................................      24
            3.1.3  Meetings ..............................................      24
            3.1.4  Decision Making .......................................      25
            3.1.5  Responsibilities of the JSC ...........................      25
     3.2    Marketing Steering Committee .................................      26
            3.2.1  Formation; Membership .................................      26
            3.2.2  Chairperson; Secretary ................................      26
            3.2.3  Meetings ..............................................      26
            3.2.4  Decision Making .......................................      27
            3.2.5  Responsibilities of the MSC ...........................      27
     3.3    Executive Steering Committee .................................      27
            3.3.1  Formation; Membership .................................      27
            3.3.2  Chairperson; Secretary ................................      28
            3.3.3  Meetings ..............................................      28
            3.3.4  Decision Making .......................................      28
            3.3.5  Dispute Resolution ....................................      28
     3.4    Authority ....................................................      29
     3.5    Project Coordinators .........................................      29

4.   RESEARCH AND DEVELOPMENT ............................................      29

     4.1    The Research Program .........................................      29
            4.1.1  General ...............................................      29
     4.2    Research & Development Plans .................................      30
            4.2.1  Global Research and Development Plan ..................      30
            4.2.2  Annual Development Plans ..............................      30
     4.3    Term of Research Program .....................................      31
            4.3.1  Screening Phase .......................................      31
            4.3.2  Research Phase ........................................      31
            4.3.3  Screening Phase Tail ..................................      31
</TABLE>

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June 26, 2003      Restated & Amended Collaboration Agreement           Page iii

<PAGE>

<TABLE>
<S>                                                                             <C>
            4.3.4  Development Phase .........................................  32
     4.4    Selection of Additional Targets, Biomolecules, Hits, Lead
            Compounds, Development Candidates and Products ...................  33
            4.4.1  Selection of Additional Targets ...........................  33
            4.4.2  Selection of Biomolecules as Compounds ....................  33
            4.4.3  Selection of Hits .........................................  33
            4.4.4  Selection of Lead Compounds ...............................  33
            4.4.5  Selection of Development Candidates .......................  33
            4.4.6  Selection of Products .....................................  34
     4.5    Conduct of the Research Program ..................................  34
            4.5.1  General ...................................................  34
            4.5.2  Discovery Headcount and Development Leadership ............  34
            4.5.3  Performance of Clinical Work ..............................  34
            4.5.4  Disagreement about Designation of a Compound as a
                   Development Candidate .....................................  35
     4.6    Funding of the Research Program ..................................  36
            4.6.1  Pre-Development Expenses ..................................  36
            4.6.2  Development Expenses ......................................  36
            4.6.3  Payment of Expenses; R&D Accounts .........................  36
            4.6.4  Expense Limitations .......................................  36
            4.6.5  Reconciliation of Expenses ................................  37
            4.6.6  Records and Audits ........................................  40
     4.7    Reporting and Disclosure .........................................  41
            4.7.1  Reports ...................................................  41
            4.7.2  Quarterly Meeting .........................................  41
            4.7.3  Disclosure ................................................  41

5.   MANUFACTURING OF PRODUCTS; REGULATORY MATTERS ...........................  41

     5.1    Manufacturing ....................................................  41
     5.2    Labeling .........................................................  42
     5.3    Regulatory Approvals .............................................  42
     5.4    Regulatory Reporting .............................................  42

6.   COMMERCIALIZATION OF PRODUCTS ...........................................  43

     6.1    Commercialization in the Copromotion Territory ...................  43
            6.1.1  Principles of Copromotion .................................  43
            6.1.2  Commercialization Plan ....................................  43
            6.1.3  Allocation of Target Markets; Sales Effort ................  44
            6.1.4  Incremental Sales Force Effort ............................  44
            6.1.5  Extra Effort ..............................................  45
            6.1.6  Performance Metrics .......................................  45
            6.1.7  Sales and Distribution; Recalls ...........................  45
            6.1.8  Commercialization Expenses ................................  46
                   (a) Pre-Marketing Expenses ................................  46
                   (b) Sales and Marketing Expenses ..........................  46
                   (c) Post-Approval Research and Regulatory Expenses ........  47
                   (d) Payment of Expenses; Marketing Accounts ...............  47
                   (e) Expense Limitations ...................................  47
                   (f) Reconciliation of Pre-Marketing Expenses ..............  47
                   (g) Reimbursement of Sales and Marketing Expenses and Post
                       Approval Research and Regulatory Expenses .............  48
            6.1.9  Marketing and Promotional Materials .......................  48
            6.1.10 Promotional Claims ........................................  49
            6.1.11 Samples ...................................................  49
            6.1.12 Communications ............................................  49
            6.1.13 Training ..................................................  50
            6.1.14 Compliance ................................................  50
            6.1.15 Generic Product ...........................................  50
     6.2    Commercialization in the Wyeth Territory .........................  51
</TABLE>

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June 26, 2003      Restated & Amended Collaboration Agreement            Page iv

<PAGE>

<TABLE>
<S>                                                                                     <C>
7.   CONSIDERATION; PROFIT SHARING ..................................................   51

     7.1    Research Program Expense Reimbursements .................................   51
     7.2    Additional Development Expense Payments .................................   51
     7.3    Purchase of Equity ......................................................   53
     7.4    Royalties ...............................................................   53
            7.4.1    Royalty Rates ..................................................   53
            7.4.2    Royalty Adjustments ............................................   55
                     (a)    Unpatented Products .....................................   55
                     (b)    Competition .............................................   55
            7.4.3    Term of Royalty ................................................   56
     7.5    Profit Sharing ..........................................................   56
            7.5.1    Baseline Allocation of Profits; Penalties ......................   56
            7.5.2    Temporary Adjustments to Distribution of Profits ...............   56
            7.5.3    Permanent Adjustment to Baseline Allocation of Profits .........   57
            7.5.2    Term of Profit Split Payments ..................................   57
     7.6    Reports and Payments ....................................................   57
            7.6.1    Cumulative Royalties ...........................................   57
            7.6.2    Royalty Statements and Payments ................................   57
            7.6.3    Net Profit Statements and Payments .............................   58
                     (a)    Estimated Statements ....................................   58
                     (b)    Actual Statements .......................................   58
            7.6.4    Taxes and Withholding ..........................................   59
            7.6.5    Currency .......................................................   59
     7.7    Maintenance of Records; Audits ..........................................   59
            7.7.1    Record Keeping for the Copromotion Territory ...................   59
            7.7.2    Record Keeping for the Wyeth Territory .........................   60
            7.7.3    Audits .........................................................   60
            7.7.4    Underpayments/Overpayments .....................................   60
            7.7.5    Confidentiality ................................................   61
     7.8    Interest ................................................................   61

8.   INTELLECTUAL PROPERTY ..........................................................   61

     8.1    Inventions ..............................................................   61
     8.2    Patent Rights ...........................................................   62
            8.2.1    Prosecution and Maintenance of Patent Rights ...................   62
                     (a)    ViroPharma's Prior Inventions and Non-Collaboration
                            Inventions ..............................................   62
                     (b)    Wyeth's Prior Inventions and Non-Collaboration
                            Inventions ..............................................   62
                     (c)    Collaboration Inventions ................................   63
            8.2.2 Enforcement of Patent Rights ......................................   64
                     (a)    Notice and Discontinuance of Infringement - General .....   64
                     (b)    Wyeth Patent Rights and ViroPharma Patent Rights ........   64
                     (c)    Collaboration Patent Rights .............................   65
                     (d)    Continuance of Infringement of ViroPharma Patent
                            Rights ..................................................   66
                     (e)    Continuance of Infringement of the Wyeth Patent
                            Rights ..................................................   66
            8.2.3    Infringement and Third Party Licenses ..........................   67
                     (a)    Infringement of Third Party Patents - Course of Action ..   67
                     (b)    Wyeth Option to Negotiate ...............................   67
                     (c)    Third Party Infringement Suit ...........................   67
                     (d)    Other Third Party Licenses ..............................   68
                     (e)    Third Party License Fees ................................   68
            8.2.4    Patent Certifications ..........................................   69
            8.2.5    Patent Term Restoration ........................................   69
     8.3    Trademarks ..............................................................   69

9.   CONFIDENTIALITY ................................................................   70

     9.1    Confidentiality .........................................................   70
     9.2    Authorized Disclosure and Use ...........................................   70
            9.2.1    Disclosure .....................................................   71
            9.2.2    Use ............................................................   71
</TABLE>

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June 26, 2003      Restated & Amended Collaboration Agreement             Page v

<PAGE>

<TABLE>
<S>                                                                             <C>
     9.3      SEC Filings................................................       71
     9.4      Publications...............................................       71
     9.5      Public Announcements.......................................       72
              9.5.1    Coordination......................................       72
              9.5.2    Announcements.....................................       72

10.  REPRESENTATIONS AND WARRANTIES......................................       72

     10.1     Representations and Warranties of Each Party...............       72
     10.2     Additional Representations and Warranties of ViroPharma....       73
     10.3     Additional Representations and Warranties of Wyeth.........       75
     10.4     Representation by Legal Counsel............................       76
     10.5     No Inconsistent Agreements.................................       76
     10.6     Disclaimer.................................................       76

11.  GOVERNMENT APPROVALS; TERM AND TERMINATION..........................       76

     11.1     Government Approvals.......................................       76
              11.1.1   ViroPharma's and Wyeth's Obligations..............       76
              11.1.2   Cooperation.......................................       77
     11.2     Term.......................................................       77
     11.3     Expiration.................................................       77
     11.4     Termination for Cause......................................       77
              11.4.1   Termination for Cause.............................       77
              11.4.2   Effect of Termination for Cause on License........       78
     11.5     Termination for Convenience................................       78
              11.5.1   Right to Terminate................................       78
              11.5.2   Effect of Termination for Convenience.............       78
     11.6     Termination of ViroPharma's Right to Promote Products......       79
              11.6.1   Failure to Provide Assigned Sales Force Effort....       79
              11.6.2   Payment and Term of Royalty.......................       81
              11.6.3   Effect on Other Rights and Obligations............       81
     11.7     Blocking Patents...........................................       81
     11.8     Survival of Certain Obligations............................       81
     11.9     Provision for Insolvency...................................       82
              11.9.1   Termination.......................................       82
              11.9.2   Effect on Licenses................................       82
              11.9.3   Rights to Intellectual Property...................       83
              11.9.4   Additional Rights.................................       83

12.  INDEMNIFICATION AND INSURANCE.......................................       84

     12.1     Indemnification by Wyeth...................................       84
     12.2     Indemnification by ViroPharma..............................       85
     12.3     Procedure..................................................       85
     12.4     Insurance..................................................       86

13.  MISCELLANEOUS.......................................................       86

     13.1     Assignment.................................................       86
     13.2     Further Actions............................................       86
     13.3     Force Majeure..............................................       86
     13.4     Correspondence and Notices.................................       87
              13.4.1   Ordinary Notices..................................       87
              13.4.2   Extraordinary Notices.............................       87
     13.5     Amendment..................................................       88
     13.6     Waiver.....................................................       88
     13.7     Severability...............................................       88
     13.8     Descriptive Headings.......................................       88
     13.9     Governing Law..............................................       89
</TABLE>

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June 26, 2003      Restated & Amended Collaboration Agreement            Page vi

<PAGE>

<TABLE>
         <S>                                                                 <C>
         13.10    Entire Agreement of the Parties........................    89
         13.11    Independent Contractors................................    89
         13.12    Debarment..............................................    89
         13.13    Counterparts...........................................    89
</TABLE>

                                LIST OF EXHIBITS

Exhibit 1.7                Wyeth Patent Rights
Exhibit 1.18               Class A Product Chemical Series
Exhibit 1.23               Collaboration Targets
Exhibit 1.50               Elements of Fully-Absorbed Standard Costs
Exhibit 1.114              ViroPharma Patent Rights
Exhibt 4.65(b)(ii-iii)     Sample Calculation of Certain Reconciliation Amounts
Exhibit 5.4                Adverse Event Reporting Procedures
Exhibit 7.3                Stock Purchase Agreement
Exhibit 7.4.1              Sample Calculation of Royalty Distributions
Exhibit 7.5.3              Sample Calculation of Net Profit Distributions
Exhibit 10.2(a)            Third Party Rights, Title or Interest in ViroPharma
                           Intellectual Property
Exhibit 10.2(b)            Third Party Claims on ViroPharma Patent Rights and
                           Know-How
Exhibit10.2(c)             ViroPharma Intellectual Property Subject to
                           Government Funding Agreements
Exhibit 10.3(a)            Third Party Claims on Wyeth Patent Rights and
                           Know-How

--------------------------------------------------------------------------------
June 26, 2003      Restated & Amended Collaboration Agreement           Page vii

<PAGE>

                           FIRST AMENDED AND RESTATED
                       COLLABORATION AND LICENSE AGREEMENT

     THIS AMENDED AND RESTATED COLLABORTION AND LICENSE AGREEMENT (the
"Agreement") dated this 26/th/ day of June, 2003 (the "Restatement Date") by and
between Wyeth (formerly known as "American Home Products Corporation")
("Wyeth"), a Delaware Corporation, having a place of business at 5 Giralda
Farms, Madison, New Jersey 07940 and ViroPharma Incorporated ("ViroPharma"), a
Delaware corporation having a place of business at 405 Eagleview Boulevard,
Exton, Pennsylvania 19341, amends and restates the Collaboration and License
Agreement dated December 9, 1999, by and between Wyeth and ViroPharma (the
"Original Agreement") and itself has an Effective Date of December 9, 1999 (the
"Effective Date"). This Agreement supercedes, merges, and cancels the Original
Agreement. Wyeth and ViroPharma may each be referred to herein individually as a
"Party" and collectively as the "Parties".

     WHEREAS, Wyeth is engaged in the research, development and
commercialization of human pharmaceutical products;

     WHEREAS, ViroPharma is the owner of certain patent rights and know-how
relating to the hepatitis C virus and compounds and methods for treating humans
infected with the hepatitis C virus;

     WHEREAS, Wyeth and ViroPharma have agreed to collaborate, on the terms and
conditions set forth herein, on the development and commercialization of
compounds for the treatment of humans infected with the hepatitis C virus.

     NOW THEREFORE, in consideration of the mutual promises and covenants set
forth below and other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the Parties hereby agree as
follows:

1.   DEFINITIONS.

     1.1  "Acquiring Entity" shall mean a Third Party that comes into control
          (as such term is defined in Section 1.4 hereof) of a Party or any of a
          Party's Affiliates through a Change in Control of such Party or such
          Affiliate occurring after the Effective Date hereof, and all other
          Third Parties controlling, controlled by or under common control with
          such Third Party, which Third Parties are not otherwise an Affiliate
          of such Party hereunder.

     1.2  "Active Collaboration Target" shall mean a Collaboration Target (a)
          that is not discontinued from use in accordance with Section 4.4.1 or
          (b) against which an Active Compound has been determined to have
          activity during the Screening Phase or Screening Phase Tail, whether
          or not such Collaboration Target has been discontinued from use in
          accordance with Section 4.4.1. Notwithstanding the foregoing, if, at
          any time after the end of the Screening Phase Tail, (a) a
          Collaboration Target has been discontinued from use in accordance with
          Section

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          4.4.1, (b) the use of such Collaboration Target has not been
          reinstated in accordance with Section 4.4.1, and (c) all Compounds
          which, during the Screening Phase or the Screening Phase Tail, were
          determined to have activity against such Collaboration Target and all
          Derivatives of such Compounds are no longer Active Compounds, then
          such Collaboration Target shall thereafter not be an Active
          Collaboration Target for purposes of this Agreement. Notwithstanding
          anything to the contrary in this Section 1.2, on and after the
          Restatement Date "Active Collaboration Target" may include only, but
          need not include, ****************.

     1.3  "Active Compound" shall mean a Compound that is being Researched,
          Developed or Commercialized by either of the Parties pursuant to this
          Agreement. For the sake of clarity, when the JSC or the MSC, as
          applicable, determines to discontinue the Research, Development or
          Commercialization of a Compound, such Compound shall no longer be an
          Active Compound for purposes of this Agreement.

     1.4  "Affiliate(s)" shall mean, with respect to each Party hereto, any
          corporation, company, partnership, joint venture, firm and/or other
          entity that controls, is controlled by or is under common control with
          such Party. For purposes of Section 1.1 and this Section 1.4,
          "control" shall mean (x) in the case of corporate entities, direct or
          indirect ownership of at least fifty percent (50%) of the stock or
          shares having the right to vote for the election of directors (other
          than such ownership by an employee benefit plan (or related trust)
          sponsored or maintained by a Party), and (y) in the case of
          non-corporate entities, direct or indirect ownership of at least fifty
          percent (50%) of the equity interest with the power to direct the
          management and policies of such non-corporate entities.
          Notwithstanding the foregoing, for purposes of this Agreement, the
          term "Affiliate" shall not include

          (a)  subsidiaries or any other entities in which a Party owns a
               majority of the ordinary voting power necessary to elect a
               majority of the board of directors or other governing board but
               is restricted from electing such majority by contract or
               otherwise until such time as such restrictions are no longer in
               effect, or

          (b)  an Acquiring Entity that comes into control of ViroPharma or a
               parent company Affiliate of ViroPharma after the Effective Date
               hereof, provided that ViroPharma, on or before the date such
               Change of Control becomes effective, delivers to Wyeth written
               notice stating that such Acquiring Entity shall not be considered
               to be an Affiliate of ViroPharma and shall be considered to be a
               Third Party for all purposes of this Agreement and, provided
               further, that, by written agreement (a copy of which shall be
               provided to Wyeth along with the notice described above in this
               Section 1.4(b)) between ViroPharma and such Acquiring Entity,
               such

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               written agreement to be entered into either before or promptly
               after such Change of Control becomes effective and to designate
               Wyeth as a third party beneficiary, such Acquiring Entity shall
               have (i) no right, title or interest in or to any Product
               hereunder, including, without limitation, the right to
               participate in the Copromotion of any Product in the Copromotion
               Territory (other than any such right, title or interest that may
               be merely incidental to the Acquiring Entity's having an equity
               interest in ViroPharma, e.g., an ownership interest in or right
               to receive a share of ViroPharma's profits), (ii) no right to
               participate in any of the activities to be conducted by or on
               behalf of ViroPharma or ViroPharma's Affiliates hereunder or to
               exercise any of ViroPharma's rights hereunder (other than any
               such right that may exist as a result of a director or employee
               of the Acquiring Entity serving as an officer or director of
               ViroPharma, provided, however, that each such director or
               employee shall not utilize any information gained through
               participating in such activities for the benefit of the Acquiring
               Entity in any way that the Acquiring Entity is prohibited from
               using such information pursuant to this Section 1.4), and (iii)
               no access to or right to use, itself or on behalf of any Third
               Party or to permit any Third Party to use, in either case for the
               discovery, development and/or commercialization of pharmaceutical
               products in the Field, any

                    (A)  of the ViroPharma Technology,

                    (B)  Compound included within the ViroPharma Chemical
                         Library,

                    (C)  of the Wyeth Technology,

                    (D)  Compound included with the Wyeth Chemical Library, or

                    (E)  Confidential Information of either Party relating to
                         the Field, the Research Program or either Party's
                         activities under this Agreement,

               (except to the extent that any of the foregoing constitute
               Permitted Materials (as such term is defined below in this
               Section 1.4), it being understood, however, that in the event
               that either (xx) the written agreement between ViroPharma and
               such Acquiring Entity described above expires or is later
               terminated, (yy) ViroPharma provides Wyeth with written notice
               that it desires such Acquiring Entity to be considered an
               Affiliate hereunder or (zz) such Acquiring Entity otherwise gains
               access to or the right to use, itself

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               or on behalf of any Third Party, any materials or information
               included within items A through E, inclusive, described in clause
               (iii) above for the discovery, development and/or
               commercialization of pharmaceutical products in the Field, except
               to the extent that such material or information constitutes
               Permitted Materials, such Acquiring Entity thereafter shall be
               considered to be an Affiliate of ViroPharma for all purposes of
               this Agreement, including, without limitation, the provisions set
               forth in Section 2.6 hereof. For purposes of this Section 1.4,
               "Permitted Materials" shall mean any of items A through E,
               inclusive, described above in this Section 1.4, which

                    (I)   the Acquiring Entity can demonstrate, through written
                          records created prior to the effective date of the
                          Change of Control of ViroPharma, was in the Acquiring
                          Entity's prior possession, other than through receipt,
                          directly or indirectly from ViroPharma,

                    (II)  the Acquiring Entity can demonstrate, through written
                          records, was acquired by the Acquiring Entity from a
                          Third Party who had the right to disclose or transfer
                          the same to the Acquiring Entity;

                    (III) the Acquiring Entity can demonstrate, through written
                          records, was independently developed by employees of
                          the Acquiring Entity who had no knowledge of or access
                          to any of items A through E, inclusive, described
                          above in this Section 1.4;

                    (IV)  becomes part of the public domain after the date this
                          Agreement was signed by the Parties other than through
                          any breach of this Agreement by ViroPharma; or

                    (V)   is made available to such Acquiring Entity by Wyeth or
                          any of Wyeth's Affiliates;

               provided, however, that none of the foregoing exclusions shall
               result in the Acquiring Entity having any right to:

                    1.   practice any of the ViroPharma Patent Rights for the
                         discovery, development and/or commercialization of
                         pharmaceutical products in the Field,

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                    2.   practice any of the Wyeth Patent Rights except through
                         a license granted by Wyeth directly to such Acquiring
                         Entity,

                    3.   practice any of the Collaboration Patent Rights for the
                         discovery, development and/or commercialization of
                         pharmaceutical products in the Field,

                    4.   utilize Compounds included within the ViroPharma
                         Chemical Library for the discovery, development and/or
                         commercialization of pharmaceutical product in the
                         Field, or

                    5.   utilize Compounds included within the Wyeth Chemical
                         Library, which Compounds are obtained directly or
                         indirectly from ViroPharma, except through a license
                         granted by Wyeth directly to such Acquiring Entity.

     1.5  "Wyeth Chemical Library" shall mean those Compounds that Wyeth, as of
          the Effective Date owns or Controls, or that come into Wyeth's Control
          during the term of the Research Program, provided, however, that for
          purposes of this Agreement, the Wyeth Chemical Library shall not
          include those Compounds in the agricultural chemical library of
          Wyeth's subsidiary, American Cyanamid Company, which agricultural
          chemical was sold to a Third Party along with the agricultural
          business of American Cyanamid Company after the Effective Date and
          prior to the Restatement Date.

     1.6  "Wyeth Know-How" shall mean Know-How, excluding the Collaboration
          Know-How, that Wyeth owns or Controls as of the Effective Date or that
          comes into the Control of Wyeth during the term of this Agreement.

     1.7  "Wyeth Patent Rights" shall mean Patent Rights that Wyeth owns or
          Controls as of the Effective Date or that come into the Control of
          Wyeth during the term of this Agreement, which Patent Rights claim any
          Wyeth Prior Invention and/or Wyeth Non-Collaboration Invention. Those
          Wyeth Patent Rights known to be existing as of the Effective Date are
          listed on Exhibit 1.7 attached hereto.

     1.8  "Wyeth Technology" shall mean the Wyeth Patent Rights, Wyeth's
          interest in the Collaboration Patent Rights, the Wyeth Know-How,
          Wyeth's interest in the Collaboration Know-How and the Wyeth Assay and
          Screening Technology.

     1.9  "Wyeth Territory" shall mean the world other than the countries
          included within the Copromotion Territory.

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     1.10 "Annual Commercialization Plan and Budget" shall have the meaning set
          forth in Section 6.1.2.

     1.11 "Annual Development Plan and Budget" shall have the meaning set forth
          in Section 4.2.2.

     1.12 "Assay and Screening Technology" shall mean the Know-How, methods and
          technology owned or Controlled by either Party which may be used for
          the screening of Compounds for activity against one or more
          Collaboration Targets.

     1.13 "Assigned Sales Force Effort" shall mean **************** in a
          ************* during any Calendar Quarter or calendar year, as
          applicable, as assigned by the MSC under the then applicable Annual
          Commercialization Plan and Budget and in accordance with Section
          6.1.3.

     1.14 "Baseline Allocation of Net Profits" shall have the meaning set forth
          in Section 7.5.1.

     1.15 "Biomolecule" shall mean a polypeptide, protein, vaccine or antibody,
          any of which is either of natural origin, expressed by recombinant
          methodology or chemically synthesized or which may be a chemical
          structure derived therefrom, an analog, derivative, congener or the
          like.

     1.16 "Calendar Quarter" shall mean the respective periods of three
          consecutive calendar months ending on March 31, June 30, September 30
          or December 31, for so long as this Agreement is in effect.

     1.17 "Change of Control" shall mean any of the following: (a) the sale or
          disposition of all or substantially all of the assets of a Party to a
          Third Party, (b) the acquisition by a Third Party, other than an
          employee benefit plan (or related trust) sponsored or maintained by a
          Party or any of its Affiliates, of more than 50% of such Party's
          outstanding shares of voting capital stock, or (c) the merger or
          consolidation of a Party with or into another corporation, other than
          a merger or consolidation of a Party in which holders of shares of
          such Party's voting capital stock immediately prior to the merger or
          consolidation will have at least 50% of the ownership of voting
          capital stock of the surviving corporation immediately after the
          merger or consolidation.

     1.18 "Class A Product" shall mean any Product that:
          ********************************.

     1.19 "Class B Product" shall mean ******************.

     1.20 "Collaboration Inventions" shall mean all Inventions owned or
          Controlled by either Party which Inventions are made by either Party's
          employees, agents or

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          subcontractors in the performance of such Party's obligations under
          the Research Program or in performing any research and development of
          a Product, pursuant to this Agreement, after such Product has received
          Regulatory Approval, including, without limitation, Phase IV clinical
          studies and clinical studies in support of additional indications
          within the Field or labeling changes for such Product during the term
          of this Agreement, regardless of whether such Inventions are made
          solely by such Party's employees, agents or subcontractors or jointly
          with the employees, agents or subcontractors of the other Party.

     1.21 "Collaboration Know-How" shall mean that Know-How that is created or
          developed by or on behalf of either Party, either alone or jointly
          with the other Party, in performing its obligations under the Research
          Program or in performing any Post-Approval Research.

     1.22 "Collaboration Patent Rights" shall mean those Patent Rights that
          include claims directed to Collaboration Inventions.

     1.23 "Collaboration Target" shall mean any Target that is (a) listed in
          Exhibit 1.23 attached hereto, (b) selected by the JSC in accordance
          with Section 4.4.1 or (c) used by either Party in its performance of
          the Research Program for Screening Compounds for potential activity as
          a prophylactic or therapeutic agent in the Field, except that on and
          after the Restatement Date, notwithstanding any other provision of
          this Agreement, or any decision of the JSC, "Collaboration Target"
          shall mean only *************.

     1.24 "Collaboration Technology" shall mean the Collaboration Patent Rights
          and the Collaboration Know-How.

     1.25 "Commercialization" shall mean any and all activities of making,
          having made, using, importing, marketing, promoting, distributing,
          offering for sale and selling a Product in the Field and shall include
          Promotion. When used as a verb, "Commercialize" shall mean to engage
          in Commercialization.

     1.26 "Commercially Reasonable Efforts" shall mean efforts and resources
          normally used by a Party for a product or compound owned by it or to
          which it has rights, which is of similar market potential at a similar
          stage in its development or product life, taking into account issues
          of safety and efficacy, product profile, the competitiveness of the
          marketplace, the proprietary position of the compound or product, the
          regulatory structure involved, the profitability of the applicable
          products, and other relevant factors.

     1.27 "Compound" shall mean a chemical compound or substance together with
          all complexes, mixtures and other combinations, prodrugs, metabolites,
          enantiomers, salt forms, racemates, and isomers thereof. For the sake
          of clarity, the term "Compounds" may include both Small Molecules and
          Biomolecules, provided, however, that, with respect to Biomolecules,
          only those Biomolecules selected for

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          collaborative Research pursuant to Section 4.4.2, shall be considered
          to be Compounds hereunder.

     1.28 "Confidential Information" shall mean with respect to each Party,
          non-public proprietary data or information which belong in whole or in
          part to such Party or its Affiliates and/or information designated as
          Confidential Information of such Party hereunder.

     1.29 "Control" or "Controlled" shall mean with respect to any (a) item of
          information, including, without limitation, Know-How, or (b)
          intellectual property right, the possession (whether by ownership or
          license, other than pursuant to this Agreement) by a Party of the
          ability to grant to the other Party access and/or a license as
          provided herein under such item or right without violating the terms
          of any agreement or other arrangements with any Third Party existing
          before or after the Effective Date.

     1.30 "Copromotion Territory" shall mean: (a) the fifty (50) states of the
          United States and the District of Columbia, and (b) Canada.

     1.31 "Copromotion Territory Commercialization Plan" shall have the meaning
          set forth in Section 6.1.2.

     1.32 "Copyright" shall mean any copyright owned or Controlled by Wyeth
          which copyright pertains to the promotional materials and literature
          utilized by the Parties in connection with the Promotion of Products
          in the Copromotion Territory pursuant to Section 6.1.

     1.33 "Cost of Goods Manufactured for Sale" shall mean Wyeth's actual cost
          to acquire Product from a Third Party, or its Fully-Absorbed Standard
          Cost to produce the Product, plus (or minus, as the case may be): (a)
          Wyeth's costs for Product inventory adjustments and losses, (b) any
          manufacturing cost variances allocable to such Product, (c)
          amortization of new standard costs for such Product, (d) prior period
          adjustments allocable to such Product, and (e) actual distribution
          costs (other than those deducted as part of the calculation of Net
          Sales pursuant to Section 1.71(a)(v)), warehousing costs and billing,
          receiving, collection and other miscellaneous costs incurred by Wyeth
          as they relate to distribution of the Products.

     1.34 "Derivative" of a given Compound shall mean a chemical compound
          derived by addition to or manipulation of a fundamental structure of
          such Compound.

     1.35 "Detail" shall mean a face-to-face meeting between one or more Target
          Physicians and one or more professional sales representative, made in
          compliance with the Target Market allocation of the MSC under Section
          6.1.3, during which a complete Product presentation, as defined from
          time to time by the MSC, is communicated, which Product presentation
          is either the first or second product-

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          related information communicated by such professional sales
          representative during such meeting. When used as a verb, "Detail"
          shall mean to perform a Detail.

     1.36 "Development" shall mean, on a country by country basis, all
          activities performed by or on behalf of either Party pursuant to the
          Global Research and Development Plan on a Compound in the Field from
          the effective date of an IND for such Compound until Regulatory
          Approval of such Compound is obtained in such country for the
          indication under study. When used as a verb, "Develop" shall mean to
          engage in Development.

     1.37 "Development Candidate" shall mean a Lead Compound or any Derivative
          thereof or any other Compound for use in the Field, that the JSC, in
          accordance with Section 4.4.5, selects or otherwise designates for
          further development to IND filing.

     1.38 "Development Expenses" shall mean, on a Compound by Compound and
          Product by Product basis, the expenses (other than Third Party License
          Fees) of the Parties incurred in performing the Development Phase of
          the Research Program and obtaining Regulatory Approval for such
          Compound or Product pursuant to the Global Research and Development
          Plan.

     1.39 "Development Phase" shall have the meaning set forth in Section 4.3.4.

     1.40 "Effective Date" shall mean December 9, 1999.

     1.41 "Executive Steering Committee" or "ESC" shall have the meaning set
          forth in Section 3.3.1.

     1.42 "Extra Effort" shall have the meaning set forth in Section 6.1.5. For
          the sake of clarity, Extra Effort shall not include any Incremental
          Sales Force Effort.

     1.43 "Extra Effort Expense" shall mean the cost to be charged to a Party's
          Marketing Account in accordance with Section 6.1.5 due to such Party's
          provision of Extra Effort.

     1.44 "FDA" shall mean the United States Food and Drug Administration or any
          successor agency thereto.

     1.45 "FD&C Act" shall mean the United States Federal Food, Drug, and
          Cosmetic Act, as amended, and the regulations promulgated thereunder.

     1.46 "Field" shall mean the therapeutic and/or prophylactic treatment of
          the effects of HCV on humans.

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     1.47 "First Commercial Sale" shall mean, with respect to any Product and
          any country of the world, the first sale of such Product under this
          Agreement, for use in the Field, to a Third Party in such country,
          after such Product has been granted Regulatory Approval for use in the
          Field by the competent Regulatory Authorities in such country.

     1.48 "FTE" shall mean a full time equivalent scientific person year
          consisting of a minimum of a total of one thousand eight hundred
          eighty hours (1,880) per year of scientific work on or directly
          related to the Research Program. Work on or directly related to the
          Research Program can include, but is not limited to, experimental
          preclinical and clinical laboratory and research work, recording and
          writing up results, reviewing literature and references, holding
          scientific discussions, managing and leading scientific staff,
          carrying out management duties related to the Research Program, and,
          only to the extent specifically pre-approved in writing by both
          ViroPharma and Wyeth, writing up results for publications or
          presentation and attending or presenting appropriate seminars and
          symposia.

     1.49 "Full Royalty Rate Period" for a Product sold in any given country
          means the period during which either or both of the following is true:

          (a)  Wyeth's distribution and/or sale of the applicable Product in the
               applicable country, in the absence of the rights and licenses
               granted by this Agreement, would have infringed one or more Valid
               Claims under Patent Rights, including Collaboration Patent
               Rights, then owned in whole or part by ViroPharma;

          (b)  Wyeth's manufacture of the Product, in the absence of the rights
               and licenses granted by this Agreement, would have infringed one
               or more Valid Claims under Patent Rights, including Collaboration
               Patent Rights, then owned in whole or part by ViroPharma,

          provided that, except as may be precluded or limited by applicable
          law, the Full Royalty Rate Period for such Product in such country
          shall not expire before the tenth (10/th/) anniversary of the First
          Commercial Sale of such Product in such country.

     1.50 "Fully-Absorbed Standard Cost" shall mean the cost for those items
          specified in Exhibit 1.50 attached hereto, which costs are calculated
          in accordance with generally accepted accounting principles and have
          been incurred by Wyeth or its Affiliates in manufacturing (i)
          materials to be used by the Parties in conducting clinical trials of
          Compounds or Products hereunder or (ii) Products for sale or
          distribution in the Copromotion Territory hereunder.

     1.51 "Global Research and Development Plan" shall have the meaning set
          forth in Section 4.2.1.

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         1.52     "Good Clinical Practice" or "GCP" shall mean the then current
                  standards for clinical trials for pharmaceuticals, as set
                  forth in the United States Federal Food, Drug and Cosmetics
                  Act and applicable regulations promulgated thereunder, as
                  amended from time to time, and such standards of good clinical
                  practice as are required by the European Union and other
                  organizations and governmental agencies in countries in which
                  the Products are intended to be sold, to the extent such
                  standards are not inconsistent with United States GCP.

         1.53     "Good Laboratory Practice" or "GLP" shall mean the then
                  current standards for laboratory activities for
                  pharmaceuticals, as set forth in the United States Federal
                  Food, Drug and Cosmetics Act and applicable regulations
                  promulgated thereunder, as amended from time to time, and such
                  standards of good laboratory practice as are required by the
                  European Union and other organizations and governmental
                  agencies in countries in which the Products are intended to be
                  sold, to the extent such standards are not inconsistent with
                  United States GLP.

         1.54     "HCV" shall mean the hepatitis C virus.

         1.55     "Hit" shall mean a Compound identified by early screening, in
                  assays conducted pursuant to protocols approved by the JSC,
                  during the Screening Phase or the Screening Phase Tail that
                  the JSC confirms, in accordance with Section 4.4.3 hereof, has
                  activity against the applicable Collaboration Target that
                  meets or exceeds an active threshold established by the JSC
                  for that Collaboration Target.

         1.56     "Incremental Sales Force Effort" shall have the meaning set
                  forth in Section 6.1.4. For the sake of clarity, "Incremental
                  Sales Force Effort" shall not include any Extra Effort.

         1.57     "Incremental Sales Force Effort Expense" shall mean the cost
                  to be charged to a Party's Marketing Account in accordance
                  with Section 6.1.4 hereof due to such Party's provision of an
                  Incremental Sales Force Effort.

         1.58     "IND" shall mean an Investigational New Drug Application, as
                  defined in the FD&C Act, that is required to be filed with the
                  FDA before beginning clinical testing of a Product in human
                  subjects, or an equivalent foreign filing.

         1.59     "Initial Term of the Screening Phase" shall have the meaning
                  set forth in Section 4.3.1.

         1.60     "Invention" shall mean any invention in the Field that
                  encompasses or relates to any Assay and Screening Technology,
                  any Collaboration Target, any Compound that is Screened,
                  Researched, or Developed under the Research Program, any
                  Derivatives of any such Compounds, any Product and any method
                  of making any such Compound, Derivative, or Product and any
                  method of using any such Compound, Derivative or Product.

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         1.61     "Joint Steering Committee" or "JSC" shall have the meaning set
                  forth in Section 3.1.

         1.62     "Know-How" shall mean, as each of the following relates to the
                  Field, all know-how, processes, materials, information, data
                  and analyses including any copyright relating thereto
                  Controlled by either Party or its Affiliates as of the
                  Effective Date or coming into the Control of either Party or
                  its Affiliates during the term of this Agreement relating to
                  any Assay and Screening Technology, any Collaboration Target,
                  any Compound that is at any time screened or developed under
                  the Research Program, any Derivatives of any such Compounds,
                  any Product and any method of making any such Compound,
                  Derivative, or Product and any method of using any such
                  Compound, Derivative or Product.

         1.63     "Lapse Quarter" for a Party shall mean, on a Product by
                  Product and country by country basis in the Copromotion
                  Territory, any Calendar Quarter in which: (a) the Party has
                  delivered less than ********** of its then current Assigned
                  Sales Force Effort, and (b) such percentage portion of its
                  then current Assigned Sales Force Effort is at **********
                  lower than the portion of the other Party's Assigned Sales
                  Force Effort actually performed by such other Party.

         1.64     "Lapse Year" for a Party shall mean, on a Product by Product
                  and country by country basis in the Copromotion Territory, any
                  calendar year in which such Party has three (3) or more Lapse
                  Quarters.

         1.65     "Lead Compound" shall mean a Compound with: (a) sufficient
                  potency and selectivity, based on activity against a
                  Collaboration Target and activity in secondary selectivity
                  assays, which activity levels and selectivity indices have
                  been established by the JSC, (b) chemical tractability, (c) a
                  preliminary indication of chemical structure-activity
                  relationships and (d) a clear basis for initiating chemical
                  optimization.

         1.66     "Major European Country" shall mean any of France, Germany,
                  Italy, or the United Kingdom.

         1.67     "Marketing Account" shall have the meaning set forth in
                  Section 6.1.8(d).

         1.68     "Marketing Steering Committee" or "MSC" shall have the meaning
                  set forth in Section 3.2.

         1.69     "NDA" shall mean a New Drug Application, as defined in the
                  FD&C Act, that is required to be approved by the FDA before
                  marketing a Product, or an equivalent foreign filing.

         1.70     "Net Profits" shall mean, with respect to the sales of any
                  Product in a country of the Copromotion Territory, the Net
                  Sales of such Product in such country, less the

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                  following expenses (deducted in the sequence listed) allocable
                  to such Product in such country: (a) the Cost of Goods
                  Manufactured for Sale, and (b) the Parties' combined Sales and
                  Marketing Expenses, a Party's Incremental Sales Force
                  Expenses, if any, a Party's Extra Effort Expense, if any, and
                  the Parties' combined Post-Approval Research and Regulatory
                  Expenses.

         1.71     "Net Sales" shall mean the gross amounts charged for sales of
                  Products by Wyeth, its Affiliates, or sublicensees, as
                  appropriate, to non-Affiliate Third Parties on which payments
                  are due under this Agreement, less the sum of (a) and (b)
                  where (a) is a provision, determined under Generally Accepted
                  Accounting Principles in the United States, for (i) reasonable
                  trade, cash and quantity discounts or rebates (other than
                  price discounts granted at the time of sale), reasonable
                  service allowances and reasonable broker's or agent's
                  commissions, if any, actually allowed or paid, (ii) credits or
                  allowances actually given or made for rejection or return of,
                  previously sold Products or for retroactive price reductions
                  (including Medicaid, managed care and similar types of
                  rebates), (iii) taxes, duties or other governmental charges
                  levied on or measured by the billing amount (excluding income
                  and franchise taxes), as adjusted for rebates and refunds, and
                  (iv) reasonable credits or allowances actually given or made
                  for wastage replacement, and (v) charges actually incurred for
                  packing, freight, and shipping from Wyeth's or its Affiliates'
                  distribution center and insurance directly related to such
                  packing, freight, and shipping of such Product (excluding
                  amounts reimbursed by Third Party customers and any amounts
                  associated with packing, freight, and shipping to and holding
                  at Wyeth's or its Affiliate's distribution center, which
                  amounts are included within the Cost of Goods Manufactured for
                  Sale) and (b) is a periodic adjustment of the provision
                  determined in (a) to reflect amounts actually incurred for
                  (i), (ii), (iii), (iv), and (v). A "sale" of a Product is
                  deemed to occur upon the invoicing, or if no invoice is
                  issued, upon the earlier of shipment or transfer of title in
                  the Product to a Third Party. If a Product is sold or
                  distributed for use in combination with or as a component of
                  another product or products (a "Combination Product"), the
                  calculation of "Net Sales" from such Combination Product will
                  be determined by multiplying the Net Sales for such
                  Combination Product calculated as set forth above by a
                  fraction, the numerator of which is the fair market value of
                  the Product in such Combination Product, and the denominator
                  of which is the fair market value of the Combination Product.
                  If a Product is sold as part of a bundle of distinct products
                  (i.e., not (i) packaged together with another product or (ii)
                  in a Combination Product form alone,) the Net Sales for such
                  Product will be based on the discounted unit price of such
                  Product sales, which discounted unit price shall be
                  proportional to the total discount provided for the entire
                  bundle (e.g., if, the price for the bundle of products is
                  twenty percent (20%) lower than the price that would be
                  charged by Wyeth, its Affiliates or sublicensees for the same
                  group of products if sold separately, based on the average
                  unit price of such products when sold separately, then the
                  discounted unit price attributable to the Product when sold as
                  part of such bundle would be eighty percent (80%) of the
                  average unit price of the Product when sold separately by
                  Wyeth, its Affiliates or sublicensees.

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         1.72     "Non-Collaboration Invention" of a Party shall mean an
                  Invention owned or Controlled by either Party, which Invention
                  (a) is made solely by such Party's employees, agents or
                  subcontractors during the term of this Agreement or otherwise
                  comes into the Control of such Party during the term of this
                  Agreement and (b) is not made in the performance of the
                  Research Program.

         1.73     "Option Period" means on a Compound-by-Compound basis, for any
                  Compound that ViroPharma has begun developing on its own
                  pursuant to Section 4.5.4, the period extending until the
                  earlier of:

                  (a)      fifteen (15) business days after Wyeth's receipt of
                           written notice from ViroPharma that the FDA has
                           accepted for review an NDA for such Compound,
                           provided that, (i) such notice has been accompanied
                           by all data regarding such Compound that has not been
                           previously disclosed to Wyeth, and (ii) at least
                           thirty (30), and no more than sixty (60) days, before
                           the submission of such NDA to the FDA, ViroPharma
                           provided Wyeth with written notice during Wyeth's
                           normal business hours of its intent to submit such
                           NDA, accompanied by all data regarding such Compound
                           that had not been previously disclosed to Wyeth; or

                  (b)      ninety (90) days after Wyeth's receipt of written
                           notice from ViroPharma that ViroPharma has submitted
                           an NDA for such Compound to FDA for review, provided
                           that, (i) such notice has been accompanied by all
                           data regarding such Compound that has not been
                           previously disclosed to Wyeth, and (ii) the FDA
                           accepts such NDA for review in materially the form
                           submitted.

         1.74     "Patent Rights" shall mean any and all (a) patents, (b)
                  pending patent applications, including, without limitation,
                  all provisional applications, substitutions, continuations,
                  continuations-in-part, divisions, renewals, and all patents
                  granted thereon, and (c) all patents-of-addition, reissues,
                  reexaminations and extensions or restorations by existing or
                  future extension or restoration mechanisms, including, without
                  limitation, supplementary protection certificates or the
                  equivalent thereof, that, (i) during the Term of this
                  Agreement, are owned or Controlled by either Party, and (ii)
                  claim any Invention.

         1.75     "Penalty Year" for a Party shall mean the calendar year
                  following a Lapse Year.

         1.76     "Phase I Clinical Study" shall mean a study, conducted in
                  accordance with a protocol approved by the JSC, of a
                  Development Candidate in human volunteers or patients with the
                  endpoint of determining initial tolerance, safety and/or
                  pharmacokinetic information in single dose, single ascending
                  dose, multiple dose and/or multiple ascending dose regimens.

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         1.77     "Phase II Clinical Study" shall mean a study, conducted in
                  accordance with a protocol approved by the JSC, of a
                  Development Candidate in patients to determine initial
                  efficacy and dose range finding before embarking on Phase III
                  Clinical Studies.

         1.78     "Phase III Clinical Study" shall mean a pivotal study in
                  patients, conducted in accordance with a protocol approved by
                  the JSC, which protocol is designed to ascertain efficacy and
                  safety of a Product for the purpose of preparing and
                  submitting applications for Regulatory Approval to the
                  competent Regulatory Authorities in a country of the world.

         1.79     "Post-Approval Research and Regulatory Expenses" shall mean
                  those expenses incurred, on a Product by Product and country
                  by country basis, by either Party directly attributable to (a)
                  ongoing research and development of a Product after such
                  Product has received Regulatory Approval in such country of
                  the Copromotion Territory, including, without limitation,
                  Phase IV clinical studies and clinical studies in support of
                  additional indications within the Field or labeling changes
                  for such Product in such country and/or (b) complying with its
                  regulatory reporting obligations in the Copromotion Territory
                  in accordance with Section 5.4.

         1.80     "Pre-Development Expenses" shall mean, on a Compound by
                  Compound basis, the expenses (other than Third Party License
                  Fees) incurred by the Parties after the Effective Date in
                  performing the Screening Phase and the Research Phase of the
                  Research Program.

         1.81     "Pre-Marketing Expenses" shall mean those expenses incurred on
                  a country by country and Product by Product basis within the
                  Copromotion Territory, by either Party, other than R&D
                  Expenses, before Regulatory Approval of a Product in such
                  country, directly attributable to the carrying out of such
                  Party's obligations under the Copromotion Territory
                  Commercialization Plan in preparation for the marketing,
                  promotion, sale and distribution of such Product in such
                  country. Such expenses may include, without limitation, costs
                  incurred for professional education, Product related public
                  relations, relationships with opinion leaders and professional
                  societies, market research, health care economics studies, and
                  establishment of the supply chain for the distribution and
                  sale of such Product in such country. Such expenses may
                  include both internal expenses incurred by a Party as well as
                  out-of-pocket expenses paid to Third Parties by a Party at
                  reasonable rates pre-approved by the MSC.

         1.82     "Pre-Marketing Expense Shortfall" shall have the meaning set
                  forth in Section 6.1.8(f).

         1.83     "Prior Invention" of a Party shall mean an Invention owned or
                  Controlled by either Party, which Invention is made solely by
                  the Party's employees, agents or

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                  subcontractors before the Effective Date or which otherwise
                  came into the Control of such Party before the Effective Date.

         1.84     "Product" shall mean any pharmaceutical product, for use in
                  the Field, containing one or more Development Candidates as an
                  active ingredient.

         1.85     "Promotion" shall mean those activities, including, without
                  limitation, Detailing and distributing Samples of a Product,
                  normally undertaken by a pharmaceutical company's sales force
                  to implement marketing plans and strategies aimed at
                  encouraging the appropriate use of a particular Product. When
                  used as a verb, "Promote" shall mean to engage in such
                  activities.

         1.86     "R&D Account" shall have the meaning set forth in Section
                  4.6.3.

         1.87     "R&D Reimbursement Account" shall have the meaning set forth
                  in Section 7.1(b).

         1.88     "R&D Shortfall" shall have the meaning set forth in Section
                  4.6.5.

         1.89     "Reduced Royalty Rate Period" for a Product in a country means
                  the period beginning on the expiration of the Full Royalty
                  Rate Period for the Product in that country, or if there is no
                  Full Royalty Rate Period for that Product in that country,
                  then beginning on the First Commercial Sale of the Product in
                  that Country, and ending on the twenty-fifth (25th)
                  anniversary of the Effective Date.

         1.90     "Regulatory Approval" shall mean the technical, medical and
                  scientific licenses, registrations, authorizations and
                  approvals (including, without limitation, approvals of NDAs,
                  supplements and amendments, pre- and post- approvals, pricing
                  and third party reimbursement approvals, and labeling
                  approvals) of any national, supra-national, regional, state or
                  local regulatory agency, department, bureau, commission,
                  council or other governmental entity, necessary for the
                  commercial manufacture, distribution, marketing, promotion,
                  offer for sale, use, import, export and sale of Product(s) in
                  a regulatory jurisdiction.

         1.91     "Regulatory Authority" shall mean any national (e.g., the
                  United States Food and Drug Administration), supra-national
                  (e.g., the European Commission, the Council of the European
                  Union, or the European Agency for the Evaluation of Medicinal
                  Products), regional, state or local regulatory agency,
                  department, bureau, commission, council or other governmental
                  entity in each country of the world involved in the granting
                  of Regulatory Approval for the Product.

         1.92     "Research" shall mean, on a Compound by Compound basis, those
                  preclinical activities undertaken by or on behalf of either
                  Party pursuant to the Global Research and Development Plan
                  subsequent to Screening and prior to Development of such
                  Compound, including, without limitation, medicinal

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                  chemistry, pharmacology, preclinical toxicology, and
                  formulation of such Compound in the Field.

         1.93     "Research Phase" shall have the meaning set forth in Section
                  4.3.2.

         1.94     "Research Program" shall have the meaning set forth in Section
                  4.1.

         1.95     "Sales and Marketing Expenses" shall mean those expenses
                  directly allocable, on a Product by Product and country by
                  country basis, to the Parties' market development and/or
                  Promotion of such Product in the Copromotion Territory,
                  consistent with the Copromotion Territory Commercialization
                  Plan for such Product. Sales and Marketing Expenses shall
                  include: (a) costs for Promotion of the Product, excluding
                  costs of the field sales force personnel (i.e., Detailing
                  expenses, including, without limitation, salaries, bonus,
                  benefits, sales force automation, and personnel expenses --
                  telephone, supplies, postage, meetings, travel and voice mail
                  including all information technology); (b) out-of-pocket
                  payments to Third Parties incurred by such Party and
                  specifically attributable to such Party's performance under
                  the Copromotion Territory Commercialization Plan, excluding
                  Third Party License Fees, (c) costs for activities related to
                  obtaining reimbursement from payers, (d) market research costs
                  (including, without limitation, actual costs of sales and
                  marketing data), (e) marketing and advertising costs
                  (including, without limitation, cost for preparing and
                  reproducing detail aids and other promotional materials), (f)
                  professional education, (g) Product related public relations,
                  (h) costs of pharmacoeconomics studies, (i) costs for
                  manufacturing and distributing Product Samples, and (j) costs
                  for conducting seminars and establishing relationships with
                  opinion leaders and professional societies in connection with
                  the Product. Such costs will include both internal costs
                  (e.g., salaries, benefits, supplies and materials, etc.) as
                  well as the actual amounts paid to outside service providers
                  (e.g., consultants, agency fees, meeting costs, etc.). Sales
                  and Marketing Expenses will specifically exclude the cost of
                  activities that promote either Party's business as a whole
                  without being Product specific (such as corporate image
                  advertising) as well as Extra Effort Expenses, and Incremental
                  Sales Force Expenses.

         1.96     "Sample" shall mean a unit of a Product, as used by Wyeth,
                  that is not intended to be sold and is intended to promote the
                  sale of such Product. When used as a verb, "Sample" shall mean
                  to provide Samples to Target Physicians.

         1.97     "Sample Receipt Forms" shall mean those multi-part paper forms
                  (or an electronic version thereof) supplied by Wyeth for the
                  purpose of recording Detail and Sample activity performed by
                  ViroPharma sales representatives during Details. These forms
                  are also used as Sample receipts on which to obtain a
                  physician's signature in acknowledgment of the physician's
                  receipt of Samples.

         1.98     "Screening" shall mean screening and identification of
                  Compounds, including, without limitation, Compounds from the
                  ViroPharma Chemical Library or the

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                  Wyeth Chemical Library to determine whether such Compounds may
                  have activity against an Active Collaboration Target.

         1.99     "Screening Phase" shall have the meaning set forth in Section
                  4.3.1.

         1.100    "Screening Phase Tail" shall have the meaning set forth in
                  Section 4.3.3.

         1.101    "Small Molecule" shall mean any Compound that is not a
                  Biomolecule.

         1.102    "Surviving Entity" of a Change of Control of ViroPharma shall
                  mean: (a) a Third Party that has acquired substantially all of
                  the assets of ViroPharma or 100% of the outstanding shares of
                  voting capital stock of ViroPharma pursuant to a Change of
                  Control, (b) a company that results from the merger of
                  ViroPharma and another entity pursuant to a Change of Control,
                  or (c) ViroPharma if a Third Party acquires more than 50% but
                  less than 100% of the outstanding shares of voting capital
                  stock of ViroPharma pursuant to a Change of Control.

         1.103    "Tail Compound Series" shall mean a group of Compounds that
                  are structurally related and share a common pharmacophore, at
                  least one Compound of which group has been screened and found
                  by either Party to have any activity against any Collaboration
                  Target, whether or not such Compound is determined to be a
                  Hit.

         1.104    "Target" shall mean a molecular entity for which there is
                  sufficient information, data, or valid reason to believe that
                  perturbation of such entity would be sufficient to prevent or
                  affect the course of human disease caused by the HCV.

         1.105    "Target Market" shall mean the segments of the overall market
                  for a Product to whom a Party will Promote such Product.

         1.106    "Target Physician" shall mean each physician and other health
                  care professional and organization to whom either Party
                  Details a Product in the Copromotion Territory.

         1.107    "Term of the Screening Phase" shall mean, with respect to any
                  Compound, the Initial Term of the Screening Phase and all
                  extensions made thereto with respect to such Compound in
                  accordance with Section 4.3.1.

         1.108    "Third Part(y/ies)" shall mean any person(s) or entit(y/ies)
                  other than Wyeth, ViroPharma or their respective Affiliates.

         1.109    "Third Party License Fee" shall mean license fees, royalties
                  and other amounts paid to any Third Party for the license
                  under intellectual property rights of technology necessary or
                  useful for Screening, Research, Development or
                  Commercialization, which license is entered into, during the
                  term of this Agreement, by a Party pursuant to Section 8.2.3.

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         1.110    "Trademark" shall mean those registered trademarks used in
                  connection with the Commercialization of any Product by either
                  Party hereunder, provided, however, that the term "Trademark"
                  shall not include the tradename of either Party or any
                  trademark or tradedress of either Party which is not used
                  exclusively in connection with the Products Commercialized
                  under this Agreement.

         1.111    "Valid Claim" shall mean a claim that (i) in the case of any
                  unexpired United States or foreign patent, shall not have been
                  donated to the public, disclaimed, nor held invalid or
                  unenforceable by a court or government agency of competent
                  jurisdiction in an unappealed or unappealable decision, or
                  (ii) in the case of any United States or foreign patent
                  application, shall not have been canceled, withdrawn, or
                  abandoned without being refiled in another application or
                  finally rejected by an administrative agency action from which
                  no appeal can be taken, or shall not have been pending for
                  more than five years. For purposes of this definition, time
                  periods shall be measured cumulatively for claims in a later
                  filed application in a country which are substantially the
                  same as claims in an earlier filed application in that
                  country. If a claim of a patent application that ceased to be
                  a Valid Claim under (ii) due to the passage of time later
                  issues as part of a patent described within (i) then it shall
                  again be considered to be a Valid Claim effective as of the
                  issuance of such patent.

         1.112    "ViroPharma Chemical Library" shall mean those Compounds that
                  ViroPharma, as of the Effective Date owns or Controls, or that
                  come into ViroPharma's Control during the term of the Research
                  Program.

         1.113    "ViroPharma Know-How" shall mean Know-How, excluding the
                  Collaboration Know-How, that ViroPharma owns or Controls as of
                  the Effective Date or that comes into the Control of
                  ViroPharma during the term of this Agreement.

         1.114    "ViroPharma Patent Rights" shall mean Patent Rights that
                  ViroPharma owns or Controls as of the Effective Date or that
                  come into the Control of ViroPharma during the term of this
                  Agreement, which Patent Rights claim any ViroPharma Prior
                  Invention and/or ViroPharma Non-Collaboration Invention. Those
                  ViroPharma Patent Rights known to be existing as of the
                  Effective Date are listed on Exhibit 1.114 attached hereto.

         1.115    "ViroPharma Technology" shall mean the ViroPharma Patent
                  Rights, ViroPharma's interest in the Collaboration Patent
                  Rights, the ViroPharma Know-How, ViroPharma's interest in the
                  Collaboration Know-How, and the ViroPharma Assay and Screening
                  Technology.

2.       LICENSES.

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         2.1      Licenses to Wyeth. Subject to the terms and conditions of this
                  Agreement, including, without limitation, Sections 2.4 and 2.6
                  hereof, ViroPharma hereby grants to Wyeth:

                  (a)      the exclusive worldwide right and license, without
                           the right to grant sublicenses (except to Wyeth's
                           Affiliates or ViroPharma), to use the ViroPharma
                           Technology, the ViroPharma Chemical Library, and the
                           Collaboration Targets only to the extent necessary
                           for Wyeth to exercise its rights and perform its
                           obligations under the Research Program and to
                           exercise its rights and perform its obligations
                           during the Screening Phase Tail; and

                  (b)      the exclusive worldwide right and license, with the
                           right to sublicense one or more of its Affiliates,
                           ViroPharma and/or Third Parties (provided, however,
                           that in the Copromotion Territory, Wyeth may only
                           grant sublicenses to one or more or its Affiliates
                           and ViroPharma), to use the ViroPharma Technology,
                           the Collaboration Targets, and the ViroPharma
                           Chemical Library only to the extent necessary to
                           Develop and Commercialize Hits, Lead Compounds,
                           Development Candidates and Products for use in the
                           Field,

                  except that the right and license under this Section 2.1 shall
                  be cancelled on the Restatement Date with respect to any
                  activities relating to screening, research, development or
                  commercialization of any Compound directed against a Target
                  other than the Collaboration Target, and, for the sake of
                  clarity, the right and license to use the Collaboration
                  Targets shall include only ***************.

         2.2      Licenses to ViroPharma. Subject to the terms and conditions of
                  this Agreement, including, without limitation, Sections 2.4
                  and 2.6 hereof, Wyeth grants to ViroPharma:

                  (a)      the nonexclusive right and license, without the right
                           to grant sublicenses (except to ViroPharma
                           Affiliates), to use the Wyeth Technology, the Wyeth
                           Chemical Library, the ViroPharma Technology, the
                           ViroPharma Chemical Library, and the Collaboration
                           Targets only to the extent necessary for ViroPharma
                           to exercise its rights and perform its obligations
                           under the Research Program and pursuant to Section
                           4.5.4, and to exercise its rights and perform its
                           obligations during the Screening Phase Tail;

                  (b)      the nonexclusive right and license, without the right
                           to grant sublicenses (except to ViroPharma
                           Affiliates), to use the Wyeth Technology, the Wyeth
                           Chemical Library, the ViroPharma Technology, the
                           ViroPharma Chemical Library, and the Collaboration
                           Targets only to the extent necessary for ViroPharma
                           to Promote Products in the Copromotion Territory in
                           accordance with Section 6.1 of this Agreement; and

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          (c)  the nonexclusive right and license, without the right to grant
               sublicenses (except to ViroPharma Affiliates), to use the
               Trademarks and Copyrights in the Copromotion Territory during the
               term of this Agreement only to the extent such license is
               necessary for ViroPharma to Promote Products in the Copromotion
               Territory in accordance with Section 6.1 of this Agreement.

     2.3  Sublicensing to Third Party Contractors. Notwithstanding any provision
          to the contrary in this Agreement, if pursuant to Section 4.5, the JSC
          approves the utilization of one or more Third Parties to perform
          certain tasks under the Research Program, the Party entering into a
          contract with such Third Party for the performance of such services,
          may, as part of such contract, grant to such Third Party a
          nonexclusive, nontransferable, nonsublicensable license or sublicense,
          as applicable, under the ViroPharma Technology or the Wyeth
          Technology, as applicable, only to the extent and only for so long as
          such license or sublicense is necessary for such Third Party to
          perform such tasks under the Research Program. Likewise, to the extent
          that either Party enters into a contract with a Contract Sales
          Organization to perform all or part of its obligations in Promoting
          Products pursuant to Section 6.1.1 hereof, such Party may, as a part
          of such contract, grant to such Third Party a nonexclusive,
          nontransferable, nonsublicensable license or sublicense, as
          applicable, under the ViroPharma Terchnology or the Wyeth Technology,
          as applicable, only to the extent and only for so long as such license
          or sublicense is necessary for such Third Party to perform such
          Promotion. All such contracts and sublicenses entered into by either
          Party with a Contract Sales Organization shall be subject to the prior
          written approval of the MSC, which approval shall not be unreasonably
          withheld or delayed.

     2.4  Dropped Compounds. Upon the written determination of the JSC not to
          advance a Compound further in Screening, Research, Development, or
          Commercialization hereunder, such Compound shall no longer be included
          in the rights licensed by one Party to the other Party under Section
          2.1 or 2.2, provided, however, that for so long as either (a) there is
          at least one Development Candidate being studied hereunder during the
          Development Phase of the Research Program or (b) a Product is being
          marketed in the Field by Wyeth pursuant to this Agreement, neither
          Party will develop or commercialize in the Field, independently or in
          collaboration with any Third Party, such Compound or any Derivative
          thereof without the prior written consent of the other Party.

     2.5  Direct Licenses to Party Affiliates. Either Party may at any time
          request and authorize the other Party to grant licenses directly to
          Affiliates of the requesting Party by giving written notice
          designating to whom a direct license is to be granted. Upon receipt of
          any such notice, the requested Party shall enter into and sign a
          separate direct license agreement with such designated Affiliate of
          the requesting Party. All such direct license agreements shall be
          consistent with the terms and conditions of this Agreement, except for
          such modifications as may be required by the laws and regulations in
          the country in which the direct license will

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          be exercised. In countries where validity of the direct license
          agreement requires prior government approval or registration, such
          direct license agreement shall not become binding between the parties
          thereto until such approval or registration is granted, which approval
          or registration shall be obtained by the requesting Party. All costs
          of making a direct license under this Section 2.5 shall be borne by
          the requesting Party.

     2.6  Exclusive Working Relationship.

          2.6.1  Collaboration Targets. Notwithstanding the licenses granted
                 under Sections 2.1 and 2.2 hereof, it is expressly understood
                 and agreed by the Parties that:

                 (a) during the Screening Phase and the Screening Phase Tail,
                     except as otherwise permitted pursuant to Section 4.5.4,
                     ViroPharma and its Affiliates shall work exclusively with
                     Wyeth and Wyeth's Affiliates in the Screening, Research,
                     Development and Commercialization of Compounds and
                     pharmaceutical products which are directed against any
                     Collaboration Target for use in the Field, provided,
                     however, that during the term of the Screening Phase Tail,
                     either Party and/or its Affiliates shall be free to perform
                     any of the activities required to bring any Compound in a
                     Tail Compound Series to Development Candidate status,
                     either (i) exclusively with the other Party and the other
                     Party's Affiliates, or (ii) independently, after first
                     having offered to collaborate with the other Party on such
                     work, but in any case not with any Third Party, provided,
                     however, that, in either event a Compound may only be
                     declared to be a Lead Compound or a Development Candidate
                     in accordance with the procedures set forth in Section 4.4
                     hereof;

                 (b) during the Research Program, Wyeth and its Affiliates shall
                     work exclusively with ViroPharma and its Affiliates on the
                     development of Compounds which are directed against Active
                     Collaboration Targets; and

                 (c) during the term of this Agreement, neither Party nor its
                     Affiliates shall develop or commercialize any Active
                     Compound for use outside of the Field, except in
                     collaboration with the other Party and such other Party's
                     Affiliates pursuant to an agreement to be negotiated by the
                     Parties. Notwithstanding the foregoing, once a Compound has
                     ceased to be an Active Compound, the Parties and their
                     respective Affiliates shall be free to develop and/or
                     commercialize such Compound for use outside of the Field,
                     provided, however, that with respect to such Compound, as
                     of the time such Compound ceases to be an Active Compound,
                     Wyeth and its Affiliates shall have no further rights or
                     licenses under the

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                     ViroPharma Technology and ViroPharma and its Affiliates
                     shall have no further rights or licenses under the Wyeth
                     Technology.

          2.6.2  Other Targets. Notwithstanding any other provision in this
                 Agreement, on and after the Restatement Date, each Party and
                 its Affiliates would be free to perform on its own any
                 screening of Compounds against Targets other than the
                 Collaboration Target, and any research or development of
                 Compounds directed against Targets other than the Collaboration
                 Target, except that such right would not include the right to:

                 (a) use Compounds from the other Party's Chemical Library or
                     Compounds to which the other Party otherwise has
                     proprietary rights,

                 (b) screen Compounds against the Collaboration Target except to
                     the extent necessary to determine selectivity against
                     Targets other than the Collaboration Target, or

                 (c) perform research or development on any Compound that is
                     active against the Collaboration Target at the level that
                     would make such a Compound a Hit.

                 Notwithstanding the foregoing, before December 9, 2004, neither
                 Party may collaborate on any of the activities permitted under
                 this Section 2.6.2 with a Third Party who has been granted
                 rights to commercialize Compounds resulting from such
                 activities.

          2.6.3  Limitations. For the sake of clarity, Wyeth would have no
                 obligation to work exclusively with ViroPharma,

                 (a) with respect to any Biomolecule based pharmaceutical
                     products regardless of the Target of such product,

                 (b) with respect to Small Molecules based pharmaceutical
                     products directed against Targets that are not, at such
                     time, Active Collaboration Targets, and

                 (c) during the Development Phase, with respect to Small
                     Molecule based pharmaceutical products directed against
                     Targets for which no Small Molecule based pharmaceutical
                     product is then being Developed under this Agreement.

     2.7  Right of Reference. Each Party hereby grants the other a "Right of
          Reference," as that term is defined in 21 C.F.R. (S) 314.3(b), to any
          data developed under this Agreement, and a Party shall provide a
          signed statement to this effect, if requested by the other, in
          accordance with 21 C.F.R. (S) 314.50(g)(3).

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3.   MANAGEMENT OF COLLABORATION.

     3.1  Joint Steering Committee.

          3.1.1  Formation; Membership. Within thirty (30) days after the
                 Effective Date, ViroPharma and Wyeth shall establish a Joint
                 Steering Committee (the "JSC") to oversee and control the
                 collaborative discovery and preclinical and clinical
                 development of Compounds and Products directed against an
                 Active Collaboration Target for use in the Field, as further
                 described below in this Agreement. The JSC shall be composed of
                 an equal number of from two (2) to four (4) representatives
                 from each Party as appointed by such Party, which
                 representatives shall have expertise suitable to the
                 then-current activities of the collaboration. The JSC shall
                 initially have two (2) representatives from each Party, but the
                 JSC may change its size from time to time by mutual consent of
                 its members, provided, however, that the size of the JSC shall
                 be no less than four (4) members and no greater than eight (8)
                 members. A Party may replace one or more of its representatives
                 from time to time upon written notice to the other Party. From
                 time to time, the JSC may establish subcommittees to oversee
                 specific projects or activities and such subcommittees shall be
                 constituted as the JSC shall determine, but shall always
                 include at least one (1) member from each Party. The JSC will
                 exist until the termination of the Research Program, as set out
                 in Section 4.3, unless the Parties otherwise agree in writing.

          3.1.2  Chairperson; Secretary. The chairperson of the JSC shall be
                 designated by Wyeth. The chairperson will be responsible for
                 scheduling meetings of the JSC, preparing agendas for meetings,
                 sending to all JSC members notices of all regular meetings and
                 agendas for such meetings at least five (5) business days
                 before such meetings. The chairperson shall appoint a secretary
                 for each meeting who will record the minutes of the meeting,
                 circulate copies of meeting minutes to the Parties and each JSC
                 member promptly following the meeting for review, comment and
                 approval and finalize approved meeting minutes.

          3.1.3  Meetings. The JSC shall meet at least once each Calendar
                 Quarter during the term of the Research Program, unless
                 otherwise mutually agreed by the Parties. Either Party may call
                 a special meeting of the JSC on fifteen (15) days written
                 notice to the other Party and each of the JSC members. Such
                 written notice shall include an agenda for the special meeting.
                 Meetings, including, without limitation, special meetings, of
                 the JSC will alternate between the offices of the Parties,
                 unless otherwise agreed by the members of the JSC, or may be
                 held telephonically or by video-conference. Meetings of the JSC
                 shall be effective only if at least one (1)

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                 representative of each Party is in attendance or participating
                 in the meeting. Members of the JSC shall have the right to
                 participate in and vote at meetings by telephone. The most
                 senior attending representative of each Party on the JSC shall
                 have the right to vote on behalf of any members of the JSC from
                 such Party not attending a JSC meeting in person or by
                 telephone. Each Party shall be responsible for expenses
                 incurred by its employees and its members of the JSC in
                 attending or otherwise participating in JSC meetings.

          3.1.4  Decision Making. All decisions of the JSC shall be made by
                 majority vote.
                 **************************************************************.

          3.1.5  Responsibilities of the JSC. In addition to its general
                 responsibility to oversee and coordinate the development of
                 Compounds and Products in the Field according to the Global
                 Research and Development Plan and ensure a regular flow of
                 research and development information between the Parties, the
                 JSC shall in particular:

                 (a)  develop the Global Research and Development Plan and the
                      Annual Development Plan and Budget for the remainder of
                      calendar year 1999 and for calendar year 2000 within sixty
                      (60) days after the Effective Date;

                 (b)  review and update as necessary the Global Research and
                      Development Plan and develop an Annual Development Plan
                      and Budget for activities under the Global Research and
                      Development Plan for subsequent calendar years no later
                      than the October 31 immediately preceding each such
                      subsequent calendar year;

                 (c)  oversee the activities of each Party's project team that
                      is performing such Party's obligations under the Research
                      Program;

                 (d)  facilitate the flow of information between the Parties
                      with respect to all development work being conducted for
                      each Compound and Product in the Field on a worldwide
                      basis;

                 (e)  review and approve all scientific and clinical protocols,
                      which shall provide that all preclinical and clinical
                      development work under this Agreement shall be conducted
                      in accordance with GLPs and GCPs;

                 (f)  review and approve the contents and filing of INDs,
                      applications for Regulatory Approval, and related and
                      supporting submissions to Regulatory Authorities; and

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                 (g)  until such time as the MSC is formed, review and approve
                      premarketing activities and expenses.

     3.2  Marketing Steering Committee.

          3.2.1  Formation; Membership. As soon as agreed by the JSC, but not
                 later than thirty (30) days after the initiation of the first
                 Phase III Clinical Study of a Product, ViroPharma and Wyeth
                 shall establish a Marketing Steering Committee (the "MSC") to
                 develop and coordinate a Copromotion Territory
                 Commercialization Plan and Annual Commercialization Plans and
                 Budgets and to oversee the execution of each Party's
                 responsibilities in the Copromotion Territory under the
                 Copromotion Territory Commercialization Plan and the applicable
                 Annual Commercialization Plan and Budget. The MSC shall be
                 composed of an equal number of from two (2) to four (4)
                 representatives from each Party as appointed by such Party,
                 which representatives shall have expertise suitable to the
                 then-current activities of the collaboration. The MSC shall
                 initially have two (2) representatives from each Party, but the
                 MSC may change its size from time to time by mutual consent of
                 its members, provided, however, that the size of the MSC shall
                 be no less than four (4) members and no greater than eight (8)
                 members. A Party may replace one or more of its representatives
                 from time to time upon written notice to the other Party. From
                 time to time, the MSC may establish subcommittees to oversee
                 specific projects or activities and such subcommittees shall be
                 constituted as the MSC shall determine, but shall always
                 include at least one (1) member from each Party. The MSC will
                 exist for so long as a Product is Promoted by both of the
                 Parties in the Copromotion Territory pursuant to this Agreement
                 unless otherwise agreed, in writing, by the Parties.

          3.2.2  Chairperson; Secretary. The chairperson of the MSC shall be
                 designated by Wyeth. The chairperson will be responsible for
                 scheduling meetings of the MSC, preparing agendas for meetings,
                 sending to all MSC members notices of all regular meetings and
                 agendas for such meetings at least five (5) business days
                 before such meetings. The chairperson shall appoint a secretary
                 for each meeting who will record the minutes of the meeting,
                 circulate copies of meeting minutes to the Parties and each MSC
                 member promptly following the meeting for review, comment and
                 approval and finalize approved meeting minutes.

          3.2.3  Meetings. After the MSC is formed in accordance with Section
                 3.2.1, the MSC shall meet at least once each Calendar Quarter,
                 unless otherwise mutually agreed by the Parties. Either Party
                 may call a special meeting of the MSC on fifteen (15) days
                 written notice to the other Party and each of the MSC members.
                 Such written notice shall include an agenda for the special
                 meeting. Meetings, including, without limitation, special
                 meetings, of the MSC will alternate between the offices of the
                 Parties,

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                 unless otherwise agreed by the members of the MSC, or may be
                 held telephonically or by video-conference. Meetings of the MSC
                 shall be effective only if at least one (1) representative of
                 each Party is in attendance or participating in the meeting.
                 Members of the MSC shall have the right to participate in and
                 vote at meetings by telephone. The most senior attending
                 representative of each Party on the MSC shall have the right to
                 vote on behalf of any members of the MSC from such Party not
                 attending a MSC meeting in person or by telephone. Each Party
                 shall be responsible for expenses incurred by its employees and
                 its members of the MSC in attending or otherwise participating
                 in MSC meetings.

          3.2.4  Decision Making. All decisions of the MSC shall be made by
                 majority vote,
                 **************************************************************.

          3.2.5  Responsibilities of the MSC. In addition to its general
                 responsibility to oversee and coordinate the Commercialization
                 of Products in the Copromotion Territory according to the
                 Copromotion Territory Commercialization Plan, the MSC shall in
                 particular:

                 (a) not later than sixty (60) days after the filing of the
                     first application for Regulatory Approval of a Product in
                     the Copromotion Territory, complete and approve a
                     Copromotion Territory Commercialization Plan for such
                     Product and an Annual Commercialization Plan and Budget for
                     such Product covering the period through the end of the
                     first full calendar year after anticipated Regulatory
                     Approval;

                 (b) oversee and coordinate the activities of the Parties in
                     marketing, selling and distributing Products in the
                     Copromotion Territory during the Term of this Agreement
                     following Regulatory Approval of such Products in the
                     Copromotion Territory; and

                 (c) not later than September 30 of each year after formation of
                     the MSC establish an Annual Commercialization Plan and
                     Budget describing each of the Parties' Commercialization
                     activities and forecast the expected sales level of
                     Products each in the Copromotion Territory during the
                     following calendar year, which will guide the schedule of
                     production of Products.

     3.3  Executive Steering Committee.

          3.3.1  Formation; Membership. Within thirty (30) days after the
                 Effective Date, ViroPharma and Wyeth shall establish an
                 Executive Steering Committee (the "ESC") to resolve disputes
                 arising within the JSC and the MSC. The ESC shall be composed
                 of two (2) representatives appointed

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<PAGE>

                 by each of ViroPharma and Wyeth, provided, however, that no
                 such representative is also a member of either the JSC or the
                 MSC. A Party may replace one (1) or more of its representatives
                 from time to time upon written notice to the other Party. The
                 ESC shall exist until the expiration or earlier termination of
                 this Agreement.

          3.3.2  Chairperson; Secretary. The chairperson of the ESC shall be
                 designated by Wyeth. The chairperson will be responsible for
                 scheduling meetings of the ESC, preparing agendas for meetings,
                 sending to all ESC members notices of all regular meetings and
                 agendas for such meetings at least five (5) business days
                 before such meetings. The chairperson shall appoint a secretary
                 for each meeting who will record the minutes of the meeting,
                 circulate copies of meeting minutes to the Parties and each ESC
                 member promptly following the meeting for review, comment and
                 approval and finalize approved meeting minutes.

          3.3.3  Meetings. The ESC shall meet on an as needed basis, provided,
                 however, that the ESC shall meet and decide on each matter
                 presented to it within thirty (30) calendar days after each
                 such matter is referred to it by the JSC or the MSC, as
                 applicable. A matter shall be considered referred to the ESC as
                 of the date that either Party provides each member of the ESC
                 with a written description of the disputed matter, which
                 written description shall include the positions taken by each
                 member of the JSC or MSC, as applicable, as to such matter, all
                 other information relevant to such matter and a copy of the
                 minutes of each JSC or MSC meeting, as applicable, at which
                 such matter was discussed. Within ten (10) days after such
                 matter is so presented to the ESC, the chairman of the ESC
                 shall notify each member of the ESC of the date, time and
                 location of the ESC meeting to address such matter. The
                 meetings of the ESC will alternate between the offices of the
                 Parties, unless otherwise agreed by the members of the ESC, or
                 may be held telephonically or by video-conference. Meetings of
                 the ESC shall be effective only if at least one (1)
                 representative of each Party is in attendance or participating
                 in the meeting. An attending or participating representative of
                 a Party shall have the right to vote on behalf of non-attending
                 or non-participating member from such Party. Each Party shall
                 be responsible for expenses incurred by its employees and its
                 members of the ESC in attending or otherwise participating in
                 ESC meetings.

          3.3.4  Decision Making. All decisions of the ESC shall be made by
                 majority vote,
                 ***********************************************************.

          3.3.5  Dispute Resolution. If the ESC is unable to reach a decision
                 with respect to any matter, such matter shall be referred for
                 resolution ********************. The decision *****************

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<PAGE>

                 with respect to such matter pursuant to this Section 3.3.5
                 shall be final and binding upon each of the Parties.
                 Notwithstanding the foregoing, if an unresolved matter is
                 presented ******************** for resolution as provided in
                 this Section 3.3.5, ******************** refer the matter back
                 to the ESC or the JSC, as applicable, for further consideration
                 with a specified date by which the ESC or JSC, as applicable,
                 must either resolve the matter or resubmit the matter
                 **************** for final resolution.

          3.4  Authority. The Parties agree that, in voting on matters as
               described in this Article 3, it shall be conclusively presumed
               that each voting member of the JSC, MSC and ESC has the authority
               and approval of such member's respective senior management in
               casting his or her vote and decisions of the JSC, MSC and ESC
               made in accordance with this Article 3 shall be binding upon each
               of the Parties.

          3.5  Project Coordinators. Each Party shall designate one or two of
               its employees as project coordinator(s) for all of the activities
               contemplated under this Agreement. Such project coordinators will
               be responsible for the day-to-day coordination of the
               collaboration contemplated by this Agreement and will serve to
               facilitate communication between the Parties. A Party may, from
               time to time, replace its designated project coordinator(s) upon
               providing the other Party with written notice to that effect.

4.   RESEARCH AND DEVELOPMENT.

     4.1  The Research Program.

          4.1.1  General. Under the terms and conditions set forth herein, Wyeth
                 and ViroPharma will collaborate in the conduct of a
                 collaborative research program for the (i) identification and
                 validation of Targets that may become Collaboration Targets and
                 assay and screening methods utilizing such Targets and (ii) the
                 discovery, identification, screening, and pre-clinical and
                 clinical development of Compounds and Products active against
                 Collaboration Targets for use in the Field (collectively, the
                 "Research Program"). The Research Program shall consist of a
                 Screening Phase, a Screening Phase Tail, if applicable, and
                 with respect to any Compound identified by the JSC as a Hit
                 during the Screening Phase, a Research Phase and, if warranted,
                 a Development Phase. The Screening Phase of the Research
                 Program (the "Screening Phase") will be focused on the
                 development of Targets that may become Collaboration Targets,
                 assays and Screening methods and the Screening of the
                 ViroPharma Chemical Library, the Wyeth Chemical Library and any
                 other library selected by mutual agreement of the Parties for
                 the identification and validation of Hits. The Research Phase
                 of the Research Program (the "Research Phase") will be focused
                 on a medicinal chemistry program for the further evaluation of
                 Hits, the development and validation of Lead

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                 Compound candidates, including, without limitation, Derivatives
                 of Hits, screening and testing of Lead Compound candidates to
                 identify and validate Lead Compounds, the optimization of Lead
                 Compounds and their Derivatives, further preclinical Research
                 and Screening of Lead Compounds to identify and select
                 Development Candidates, and the further preclinical Development
                 of Development Candidates. The Development Phase of the
                 Research Program (the "Development Phase") will be focused on
                 the clinical Development of Development Candidates and
                 Products.

     4.2  Research & Development Plans.

          4.2.1  Global Research and Development Plan. Within thirty (30) days
                 following its formation, the JSC shall prepare and approve a
                 global research and development plan (the "Global Research and
                 Development Plan"). The Global Research and Development Plan
                 shall consist of those tasks that the Parties agree are
                 essential to the validation of Targets that may become
                 Collaboration Targets, the discovery, validation and
                 preclinical and clinical development of Compounds and Products
                 which are directed against Active Collaboration Targets for use
                 in the Field, and obtaining Regulatory Approval for Products in
                 the world. The Global Research and Development Plan shall be
                 kept current by the JSC, updated on such schedule as the JSC
                 may determine but not less often than once per calendar year.
                 The Global Research & Development Plan may only be modified or
                 amended upon written approval of the JSC.

          4.2.2  Annual Development Plans. Within thirty (30) days following its
                 formation, the JSC shall prepare and approve an annual
                 development plan and budget (the "Annual Development Plan and
                 Budget") addressing the collaborative Screening, Research and
                 Development activities to be carried out by the Parties during
                 the remainder of calendar year 1999 pursuant to this Agreement
                 and the Global Research and Development Plan. Thereafter, on or
                 before October 31 of each year, the JSC shall prepare and
                 approve an Annual Development Plan and Budget addressing the
                 collaborative Screening, Research and Development activities to
                 be undertaken by the Parties during the following calendar year
                 pursuant to this Agreement and the then current Global Research
                 and Development Plan. Each Annual Development Plan and Budget
                 shall include, without limitation, detailed plans for the
                 characterization and validation of Targets that may become
                 Collaboration Targets, the discovery and validation of
                 Compounds which are directed against Active Collaboration
                 Targets for use in the Field, the collaborative research and
                 development of Compounds and Products which are directed
                 against Active Collaboration Targets for use in the Field,
                 designation of which Party is responsible for each task,
                 staffing levels required to carry out such activities, and a
                 budget setting forth the estimated expenditures required to
                 carry out such

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                  activities. The Annual Development Plan and Budget may only be
                  modified or amended upon written approval of the JSC.

     4.3  Term of Research Program. The Research Program shall extend until the
          termination of the latest of all of the following, including, if
          applicable, the last meeting of the JSC necessary to determine whether
          Hits in the Screening Phase Tail should be advanced to Development.

          4.3.1  Screening Phase. The Screening Phase of the Research Program
                 shall begin on the Effective Date and, on a Collaboration
                 Target by Collaboration Target basis, unless extended in
                 accordance with this Section 4.3.1, shall extend until the five
                 (5) year anniversary of the Effective Date (the "Initial Term
                 of the Screening Phase") unless this Agreement is earlier
                 terminated in its entirety in accordance with Sections 11.4,
                 11.5, or 11.9.1 or with respect to such Collaboration Target in
                 accordance with Section 11.7. The Initial Term of the Screening
                 Phase of the Research Program may be extended by mutual
                 agreement of the Parties on terms substantially the same as
                 those set forth herein, unless otherwise agreed in writing by
                 the Parties. On or before the day one hundred eighty (180) days
                 before the expiration of the Initial Term of the Screening
                 Phase of the Research Program or the then current extension
                 thereof, as applicable, either Party may provide to the other
                 Party written notice of its desire to extend the Screening
                 Phase of the Research Program by one (1) additional year.
                 Promptly after the other Party's receipt of such written notice
                 the Parties shall commence discussions of the need and desire
                 to extend the Screening Phase of the Research Program and if
                 both Parties do not agree, in writing, to such extension on or
                 before the day sixty (60) days before the expiration of the
                 Initial Term of the Screening Phase or the then current
                 extension thereof, the Term of the Screening Phase shall expire
                 at the end of the Initial Term of the Screening Phase or the
                 then current extension thereof, as applicable.

          4.3.2  Research Phase. The Research Phase of the Research Program
                 shall commence, on a Compound by Compound basis, upon the JSC's
                 designation of such Compound as a Hit, and shall extend until
                 the later of (a) the initiation of the Development Phase for
                 such Compound, or (b) such time as the JSC determines, in
                 writing, to discontinue all Research on such Compound and not
                 to advance such Compound to the Development Phase, unless
                 earlier terminated in accordance with Sections 11.4, 11.5, 11.7
                 or 11.9.1.

          4.3.3  Screening Phase Tail. The Screening Phase Tail shall begin
                 during the term of this Agreement, on a Compound-by-Compound
                 basis, when such Compound is first screened and found by either
                 Party to have any activity against any Collaboration Target,
                 whether or not such Compound is determined to be a Hit, and
                 shall extend until the one (1) year anniversary

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                 of the end of the Term of the Screening Phase, unless this
                 Agreement is earlier terminated in its entirety in accordance
                 with Section 11.4 or 11.9.1 or pursuant to Section 11.7, with
                 respect to any Collaboration Target identified pursuant to
                 Section 11.7(b) for which the Research Program has been
                 terminated in accordance with Section 11.7, but regardless of
                 whether this Agreement is earlier terminated in accordance with
                 Section 11.5. Within thirty (30) days after the end of the
                 Screening Phase and within thirty (30) days after the end of
                 the Screening Phase Tail, each Party shall prepare an inventory
                 of Hits, Leads, Development Candidates, and Compounds in
                 Development. Within ten (10) business days after the end of
                 each Calendar Quarter during the Screening Phase Tail each
                 Party shall provide to the other a written report detailing all
                 data and information obtained by such Party with respect to any
                 Compound from a Tail Compound Series studied by such Party
                 during such Calendar Quarter. For the Calendar Quarter during
                 which the Screening Phase Tail ends, such written reports shall
                 be provided within ten (10) business days after the last day of
                 the Screening Phase Tail. At any time during the Screening
                 Phase Tail, either Party may propose in writing to the JSC that
                 a Compound from a Tail Compound Series subject to the Screening
                 Phase Tail be designated a Hit or Lead Compound and be further
                 developed. Additionally, within thirty (30) days after the last
                 day of the Screening Phase Tail, the JSC shall meet to
                 determine whether any of the Compounds from Tail Compound
                 Series studied by the Parties during the Screening Phase Tail
                 shall be designated as a Hit or Lead Compound and further
                 developed. If the JSC designates a Compound from a Tail
                 Compound Series as a Hit or Lead Compound, then the Parties
                 shall collaborate on further, Research, Development and
                 Commercialization of such Compound consistent with the terms of
                 this Agreement, regardless of whether this Agreement is earlier
                 terminated in accordance with Section 11.5, in which event,
                 such earlier termination shall be void and the effects of any
                 such termination arising in accordance with Section 11.5.2
                 shall be reversed such that each Party thereafter has the
                 rights it had immediately prior to such termination. If the JSC
                 in good faith determines not to designate any such Compound
                 from a Tail Compound Series as a Hit or a Lead Compound, then
                 the Party owning such Compound may further Develop and
                 Commercialize such Compound independently of the other Party
                 subject to the restrictions of Section 2.6.

          4.3.4  Development Phase. With respect to any Compound, the
                 Development Phase shall commence on the date an IND is filed
                 seeking permission from the appropriate Regulatory
                 Authority(ies) to conduct clinical studies of such Compound and
                 shall continue until the JSC agrees to cease the clinical
                 development of such Compound or until a Product containing such
                 Compound has received Regulatory Approval in the Copromotion
                 Territory and each country of the Wyeth Territory where Wyeth
                 determines to apply for Regulatory Approval.

June 26, 2003           Restated & Amended Collaboration Agreement       Page 32

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     4.4  Selection of Additional Targets, Biomolecules, Hits, Lead Compounds,
          Development Candidates and Products.

          4.4.1  Selection of Additional Targets. During the Screening Phase,
                 but subject to Section 1.23, the JSC may select one or more
                 additional Targets as Collaboration Targets against which to
                 Screen Compounds for activity. Likewise, during the term of the
                 Screening Program, but subject to Section 1.23, the JSC may
                 determine to discontinue Screening Compounds for activity
                 against one or more Targets or to reinstate the screening of
                 Compounds for activity against one or more Targets that were
                 previously discontinued from Screening.

          4.4.2  Selection of Biomolecules as Compounds. Neither Party shall
                 Screen or conduct any Research or Development under this
                 Agreement on any Compound that is a Biomolecule unless the JSC
                 first approves, in writing, the inclusion of such Biomolecule
                 as a Compound under this Agreement.

          4.4.3  Selection of Hits. The JSC shall review the data obtained by
                 the Parties in the Screening of Compounds, and, upon agreement
                 that such data support a determination that such Compound has
                 activity against the applicable Collaboration Target that meets
                 or exceeds an active threshold established by the JSC for that
                 Collaboration Target, such Compound shall be deemed to be a
                 Hit.

          4.4.4  Selection of Lead Compounds. Based on criteria to be determined
                 by the JSC, the JSC may select Lead Compounds during the
                 Screening Phase, the Screening Phase Tail or the Research Phase
                 from (a) Hits in the ViroPharma Chemical Library, the Wyeth
                 Chemical Library or any other library the Parties shall
                 mutually agree to screen in connection with the Research
                 Program, and/or (b) any Derivative of any such Hits.

          4.4.5  Selection of Development Candidates. During the Research Phase,
                 the JSC may select Development Candidates from those Compounds
                 designated by the JSC as Lead Compounds and any Derivatives
                 thereof. The JSC's selection of Development Candidates shall be
                 based upon the JSC's determination to develop such Compound
                 toward IND filing, based on criteria established by the JSC,
                 which criteria may include, without limitation, consideration
                 of the following factors: in vitro efficacy and potency, in
                 vivo oral activity, efficacy and potency, medicinal chemistry
                 criteria, toxicology studies required for IND filing, ancillary
                 pharmacology studies, clinical drug substance stability and
                 formulation, scale up compound synthesis and other competitive
                 and commercial factors, including without limitation, the
                 proprietary position of such Compound.

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          4.4.6  Selection of Products. Development Candidates will become
                 Products upon the filing of an IND for such Development
                 Candidate, which filing will be made only after the JSC
                 determines that such Development Candidate is suitable for
                 clinical trials based on its preclinical profile and
                 competitive and other commercial considerations.

     4.5  Conduct of the Research Program.

          4.5.1  General. ViroPharma and Wyeth shall each use its respective
                 Commercially Reasonable Efforts to perform its obligations
                 under the Research Program in accordance with the Global
                 Research and Development Plan and the then current Annual
                 Development Plan and Budget and each Party shall perform such
                 obligations in accordance with applicable GLPs and GCPs.
                 ViroPharma and Wyeth shall each use its respective Commercially
                 Reasonable Efforts to together advance up to five (5) Compounds
                 to Product status by March 18, 2006. All activities to be
                 undertaken in the performance of the Research Program shall be
                 carried out by employees of the Parties and/or their respective
                 Affiliates, provided, however, that if either Party is able to
                 reasonably demonstrate, and the JSC agrees, that it would be in
                 the best interests of both Parties to contract with one (1) or
                 more Third Parties to perform certain tasks under the Research
                 Program, the Party responsible for such task may enter into a
                 contract with a Third Party to perform such task, which
                 contract shall be subject to the prior written approval of the
                 JSC. In determining whether to utilize the services of any
                 Third Party in conducting activities under the Research
                 Program, the Parties shall consider, inter alia, what would be
                 the most efficient and cost-effective means for accomplishing
                 the proposed activity, any relevant intellectual property
                 issues that may impede a Third Party's ability to perform the
                 proposed activity or that may warrant limiting the performance
                 of the proposed activity to one of the Parties, and other
                 relevant factors.

          4.5.2  Discovery Headcount and Development Leadership. Wyeth shall
                 lead Research on any ******** Compounds and ViroPharma shall
                 lead Research on any ********* Compounds, in each case up to
                 and including the filing of an IND for such Compounds. The JSC
                 shall determine which Party will lead the further Development
                 of these Compounds and of any other Compound families, in each
                 case in the best interests of the alliance. The Parties shall
                 collectively devote ******** FTEs to Screening and Research
                 activities, unless otherwise agreed by unanimous vote of the
                 JSC. Of these, ViroPharma shall contribute ********* and
                 ***********, and Wyeth shall contribute *********** and
                 **********, unless otherwise agreed by unanimous vote of the
                 JSC.

          4.5.3  Performance of Clinical Work. The responsibility for performing
                 clinical studies of each Product will be assigned to Wyeth
                 and/or Third

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                 Party contractors selected by the JSC in accordance with this
                 Section 4.5. Notwithstanding the foregoing, ViroPharma shall be
                 given the opportunity to perform three (3) clinical studies in
                 the Development of Products in the Copromotion Territory under
                 this Agreement, which clinical studies shall consist of one (1)
                 Phase I Clinical Study, one (1) Phase II Clinical Study and one
                 (1) Phase III Clinical Study, ****************************.
                 Within thirty (30) days of the JSC's deciding that a clinical
                 study on a Product is warranted, *****************************.
                 If the JSC agrees, in writing, such agreement not to be
                 unreasonably withheld, ***************************, the Annual
                 Development Plan and Budget for the calendar year in which such
                 clinical study is to take place shall assign responsibility for
                 such clinical study to ViroPharma, or be amended to reflect
                 such assignment of responsibility. ****************************
                 **********************************. Notwithstanding the
                 foregoing, the JSC may assign to ViroPharma responsibility for
                 conducting additional clinical trials beyond the three (3)
                 described above in this Section 4.5.

          4.5.4  Disagreement about Designation of a Compound as a Development
                 Candidate. If, (a) for ************** there has been no
                 Compound that is in Development Candidate status or beyond (for
                 the sake of clarity, Compounds which, (i) are being clinically
                 developed, (ii) for which an NDA or equivalent regulatory
                 approval is pending, or (iii) are being commercialized, would
                 all be considered to be in Development Candidate status or
                 beyond), and (b) the Parties disagree about advancing a
                 specific Lead Compound (that at such time is an Active Compound
                 directed against an Active Collaboration Target) to Development
                 Candidate status, then ViroPharma shall be permitted to develop
                 such Lead Compound on its own and at its sole expense,
                 notwithstanding any provision in Section 4.6 below to the
                 contrary. During the Option Period, (i) ViroPharma shall share
                 all data on such Compound with Wyeth, including any data
                 contained in regulatory submissions, (ii) ViroPharma shall not
                 enter into any agreement with a Third Party whereby such Third
                 Party obtains any right to develop or commercialize such
                 Compound other than in connection with an assignment by
                 ViroPharma of all of ViroPharma's rights and obligations under
                 this Agreement, to the extent permitted under Section 13.1
                 hereof, in connection with the transfer or sale of all or
                 substantially all of ViroPharma's assets, stock or business to
                 such Third Party or ViroPharma's merger or consolidation with
                 such Third Party, and (iii) notwithstanding, clause (ii) above,
                 ViroPharma, at ViroPharma's sole expense, may enter into an
                 agreement with a Third Party for the sole purpose of such Third
                 Party performing development work on such Compound on
                 ViroPharma's behalf, provided, that such Third Party obtains no
                 commercialization rights with respect to such Compound through
                 such agreement or otherwise. Until the end of the Option
                 Period,

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                 Wyeth shall have the exclusive option to reacquire the right to
                 jointly develop and commercialize such Compound as further
                 described below. If Wyeth exercises such option, Wyeth shall
                 pay ViroPharma **********************************************.
                 Thereafter, the Compound shall remain subject to the terms of
                 this Agreement for its continued Development and
                 Commercialization. If, before the end of the Option Period,
                 Wyeth has not exercised such option, ViroPharma shall pay Wyeth
                 **********************************, and Wyeth shall be entitled
                 to a royalty of ******************** of the Net Sales obtained
                 from the sale of such Compound in the world by ViroPharma, its
                 Affiliates or sublicensees.

     4.6  Funding of the Research Program.

          4.6.1  Pre-Development Expenses. The Parties shall share the
                 Pre-Development Expenses ***********.

          4.6.2  Development Expenses. The Parties shall share the Development
                 Expenses, on a Product by Product basis, as follows:

                 (a)  Wyeth shall be responsible for **************** and
                      ViroPharma shall be responsible for *************** of the
                      Development Expenses incurred by either Party.

                 (b)  Expenses incurred by the Parties for the continued
                      development of a Product in a country of the Copromotion
                      Territory (i.e., for Phase IV clinical studies, studies
                      supporting approval of additional indications or labeling
                      changes or other post-marketing studies) will be treated
                      as Post-Approval Research and Regulatory Expenses pursuant
                      to Section 6.1.8(c).

          4.6.3  Payment of Expenses; R&D Accounts. Subject to reconciliation as
                 provided in Section 4.6.5, each Party shall be responsible and
                 pay for the expenses incurred by it in performing its
                 obligations under the Research Program. Subject to the
                 limitations set forth in Section 4.6.4, each Party shall charge
                 all such expenses so incurred by it or its Affiliates to a
                 separate account created by such Party on its books and records
                 solely for the purpose of tracking expenses incurred in
                 connection with the Research Program (each, a "R&D Account").
                 Within thirty (30) days after the end of each Calendar Quarter,
                 each Party shall submit to the other Party a written summary of
                 all expenses charged to its R&D Account during such Calendar
                 Quarter, which summary shall be accompanied by reasonable
                 supporting documentation for such expenses.

          4.6.4  Expense Limitations. The expenses charged by either Party to
                 its R&D Account in accordance with Section 4.6.3, shall not be
                 in an amount in

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                 excess of *************** of the amount included for such
                 expenses in the then current Annual Development Plan and Budget
                 unless the JSC recommends and the respective R&D management of
                 each Party approves such excess expenses. Additionally, the
                 Parties hereby agree that efforts of the employees of a Party
                 or its Affiliates in performing its obligations under the
                 Research Program shall be charged to such Party's R&D Account
                 at the rate of *************************************, or such
                 other amount as may be agreed to from time to time in writing
                 by the Parties, for efforts in support of preclinical studies
                 of a Compound or otherwise performed in the Screening Phase or
                 the Research Phase of the Research Program and
                 ************************************, or such other amount as
                 may be agreed to from time to time in writing by the Parties,
                 for efforts in support of clinical studies of a Compound or
                 Product or otherwise performed as part of the Development Phase
                 of the Research Program, provided, however, that only those
                 efforts that are contemplated by the Global Research and
                 Development Plan and/or the applicable Annual Development Plan
                 and Budget shall be chargeable by a Party to its R&D Account,
                 except as otherwise approved in writing by the JSC. All
                 payments made by a Party to a Third Party in connection with
                 the performance of its obligations under the Research Program
                 shall be charged to such Party's R&D Account at such Party's
                 actual out-of-pocket cost. Expenses incurred by each Party for
                 equipment, materials and supplies utilized in performing its
                 obligations under the Research Program shall not be separately
                 charged to such Party's R&D Account, except for those expenses
                 incurred by a Party, with the prior written consent of the JSC,
                 in the purchase or making of equipment, materials or supplies
                 (other than common laboratory supplies, e.g., pipettes, test
                 tubes, petri dishes, reagents, and the like) that are to be
                 used exclusively in connection with the performance of such
                 Party's obligations under the Research Program (e.g.,
                 laboratory animals, compounds that are Development Candidates,
                 Products, placebo supplies, etc.), which expenses shall be
                 charged to such Party's R&D Account at such Party's actual
                 out-of-pocket expense incurred in purchasing or making such
                 equipment, materials or supplies. Notwithstanding the
                 foregoing, in the case of materials supplied to the Parties by
                 Wyeth for use in clinical trials of Compounds or Products,
                 Wyeth shall charge to its R&D Account its Fully Absorbed
                 Standard Cost for such materials, as adjusted to account for
                 manufacturing cost variances allocable to such materials.

          4.6.5  Reconciliation of Expenses. Within sixty (60) days after the
                 end of each Calendar Quarter, Wyeth shall prepare a
                 reconciliation report, accompanied by reasonable supporting
                 documents and calculations, which reconciles the amounts
                 charged to each Party's R&D Account during such Calendar
                 Quarter pursuant to Section 4.6.3 separately for each of
                 Pre-Development Expenses and Development Expenses, including,
                 without limitation, making any necessary adjustments for prior
                 period

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                 manufacturing cost variances allocable to Products utilized in
                 Development, and the share of the Parties' aggregate
                 Pre-Development Expenses and separately, the Parties' aggregate
                 Development Expenses to be allocated to each of the Parties for
                 such Calendar Quarter in accordance with Sections 4.6.1 and
                 4.6.2. (For the sake of clarity: two separate reconciliations
                 will be made - one for Pre-Development Expenses, and one for
                 Development Expenses, and the amount of any R&D Shortfall
                 attributable to Pre-Development Expenses shall not be set-off
                 against the amount of any R&D Shortfall attributable to
                 Development Expenses.) Within thirty (30) days after Wyeth
                 delivers such reconciliation report to ViroPharma (the "R&D
                 Payment Period"), the net amount shown as being due either
                 Wyeth or ViroPharma for each of Pre-Development Expenses and
                 Development Expenses (each, an "R&D Shortfall") will be paid by
                 the Party owing such amount, provided, however, that in the
                 event ViroPharma is the Party owing either or both such amounts
                 to Wyeth,

                 (a)  in 2002, if both ViroPharma and Wyeth have an R&D
                      Shortfall, and ViroPharma's R&D Shortfall is greater, then
                      ViroPharma may, by written notice to Wyeth provided within
                      the R&D Payment Period, *********************************;
                      and

                 (b)  after 2002,

                      (i)   ViroPharma may, by written notice to Wyeth provided
                            within the R&D Payment Period, ********************,

                      (ii)  if in any single calendar year the sum of
                            ViroPharma's quarterly R&D Shortfalls for the year
                            attributable to Development Expenses, if any, less
                            the sum of Wyeth's

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<PAGE>

                            quarterly R&D Shortfalls for the year attributable
                            to Development Expenses, if any, is greater than
                            ********, then

                            a)  ****************************************,

                            b)  the reconciliation report for the last Calendar
                                Quarter of each calendar year shall include a
                                reconciliation of Pre-Development Expenses
                                *************************************, and

                      (iii) if in any single calendar year the sum of
                            ViroPharma's quarterly R&D Shortfalls for the year
                            attributable to Development Expenses, if any, less
                            the sum of Wyeth's quarterly R&D Shortfalls for the
                            year attributable to Development Expenses, if any,
                            is ********, then *********************************.

                 If, with respect to any calendar year, ViroPharma has an R&D
                 Shortfall for which it is to reimburse Wyeth, the balance in
                 the R&D Reimbursement Account has been exhausted, and
                 ViroPharma is unable or otherwise fails to pay to Wyeth all or
                 part of the R&D Shortfall before the end of the thirty (30) day
                 period required by this Section 4.6.5, then the unpaid portion
                 of the R&D Shortfall (the "Deferred Payment") shall accumulate
                 interest at the annual interest rate of twelve percent (12%),
                 compounded monthly, and shall be repaid to Wyeth
                 ***********************************************************,
                 until all such R&D Shortfalls and any interest accrued thereon
                 are paid in full. Notwithstanding the foregoing, all Deferred
                 Payments

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<PAGE>

                 and all interest accumulating thereon shall be due and payable
                 to Wyeth within seven (7) years after the end of the thirty
                 (30) day period described above in this Section 4.6.5. The
                 failure of ViroPharma to pay to Wyeth all or part of an R&D
                 Shortfall prior to the end of such seven (7) year period shall
                 not be a material breach of this Agreement for purposes of
                 Section 11.4.

          4.6.6  Records and Audits. During the term of this Agreement, each
                 Party shall keep and maintain accurate and complete records
                 showing the expenses incurred by it in performing its
                 obligations under the Research Program during the three (3)
                 preceding calendar years, which books and records shall be in
                 sufficient detail such that each such expense can be (i)
                 allocated as a Pre-Development Expense or a Development Expense
                 and (ii) in the case of Development Expenses, allocated to
                 particular clinical trials or activities such that each Party's
                 responsibility for such expenses as provided in Section 4.6.2
                 can accurately be determined. Upon fifteen (15) days prior
                 written notice from a Party (the "Auditing Party"), the other
                 Party (the "Audited Party") shall permit an independent
                 certified public accounting firm of nationally recognized
                 standing selected by the Auditing Party and reasonably
                 acceptable to the Audited Party, to examine the relevant books
                 and records of the Audited Party and its Affiliates as may be
                 reasonably necessary to verify the reports submitted by the
                 Audited Party in accordance with Section 4.6.3 and the accuracy
                 of the reconciliation report prepared in accordance with
                 Section 4.6.5. An examination by a Party under this Section
                 4.6.6 shall occur not more than once in any calendar year and
                 shall be limited to the pertinent books and records for any
                 calendar year ending not more than thirty-six (36) months
                 before the date of the request. The accounting firm shall be
                 provided access to such books and records at the Audited
                 Party's facility(ies) where such books and records are normally
                 kept and such examination shall be conducted during the Audited
                 Party's normal business hours. The Audited Party may require
                 the accounting firm to sign a standard non-disclosure agreement
                 before providing the accounting firm access to the Audited
                 Party's facilities or records. Upon completion of the audit,
                 the accounting firm shall provide both Wyeth and ViroPharma a
                 written report disclosing whether the reports submitted by the
                 Audited Party are correct or incorrect and the specific details
                 concerning any discrepancies. No other information shall be
                 provided to the Auditing Party. If the accountant determines
                 that, based on errors in the reports so submitted, the
                 reconciliation report prepared in accordance with Section 4.6.5
                 is incorrect, the Parties shall promptly revise the
                 reconciliation report and any additional amount owed by one
                 Party to the other shall be paid within thirty days after
                 receipt of the accountant's report, along with interest at the
                 annual interest rate of twelve percent (12%), compounded
                 monthly from the date that such additional amount should have
                 first been paid, provided, however, that no such interest shall
                 be payable if the errors

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<PAGE>

                 leading to the reconciliation report being incorrect were in
                 the reports provided by the Party to receive such additional
                 amount. Additionally, if the accountant determines that the
                 reports submitted by the Audited Party overstate the Audited
                 Party's expenses by more than ten percent (10%), the Audited
                 Party shall reimburse the Auditing Party for the expenses
                 incurred by the Auditing Party in conducting the audit.

     4.7  Reporting and Disclosure.

          4.7.1  Reports. Before each quarterly meeting of the JSC, ViroPharma
                 and Wyeth will each provide the other with written copies of
                 all materials they intend to present at the JSC meeting plus,
                 to the extent not set forth in the JSC materials, a written
                 report summarizing any other material data and information
                 arising out of the conduct of the Research Program. If after
                 receipt of any such report, either Party shall request
                 additional data or information relating to Research Program
                 data or Collaboration Technology licensed hereunder, the Party
                 to whom such request is made shall promptly provide to the
                 other Party such data or information that such Party reasonably
                 believes is necessary for the continued conduct of the Research
                 Program.

          4.7.2  Quarterly Meeting. At the quarterly meeting of the JSC, Wyeth
                 and ViroPharma will review in reasonable detail (i) all data
                 and information generated in the conduct of the Research
                 Program by each Party, and (ii) all Collaboration Technology
                 licensed hereunder developed by the Parties.

          4.7.3  Disclosure. During the term of the Research Program, the
                 Parties will promptly disclose to one another all data,
                 information, Inventions, techniques and discoveries (whether
                 patentable or not) arising out of the conduct of the Research
                 Program and all Inventions, techniques and discoveries (whether
                 patentable or not) included in Collaboration Technology
                 licensed hereunder.

5.   MANUFACTURING OF PRODUCTS; REGULATORY MATTERS.

     5.1  Manufacturing. Pursuant to the licenses granted to Wyeth in Section 2,
          Wyeth shall have the exclusive right to manufacture, either itself
          and/or through Third Parties selected by Wyeth, Products under the
          Agreement. To the extent possible, Wyeth shall notify ViroPharma at
          least one (1) year before any anticipated occurrence of the inability
          of Wyeth to supply one hundred fifteen percent (115%) of the
          commercial demands for Product in the Co-Promotion Territory as
          forecast by the MSC. Within fifteen (15) days of such notice the MSC
          shall meet to discuss the need to identify and obtain a secondary
          source of Product supply to avoid or reduce the effect of any
          shortage. Additionally, after the First Commercial Sale of a Product
          in the Copromotion Territory, Wyeth shall, by December 1 of each year,
          provide ViroPharma with an estimate of Wyeth's

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          expected Fully Absorbed Standard Cost for manufacturing the full
          estimated commercial needs for such Product for sale in the
          Copromotion Territory for the upcoming calendar year. Wyeth shall
          provide ViroPharma with an updated estimate from time to time if an
          unexpected event occurs that significantly raises or lowers the last
          estimate that Wyeth provided to ViroPharma.

     5.2  Labeling. To the extent permitted by applicable laws and regulations,
          as may be reasonably requested by ViroPharma, Wyeth shall include in
          all Product Labels, Labeling, and Packaging, as those terms are use in
          the FD&C Act, a statement indicating that such Product was developed
          in collaboration with ViroPharma.

     5.3  Regulatory Approvals. Wyeth shall file, in its own name, all
          applications for Regulatory Approval for Products in the Copromotion
          Territory and in those countries of the Wyeth Territory where Wyeth,
          in its sole discretion, determines it is commercially advantageous to
          do so. Wyeth shall have the primary responsibility for communicating
          with any Regulatory Authority regarding any application for Regulatory
          Approval or any Regulatory Approval once granted, provided, however,
          that ViroPharma shall, upon Wyeth's request, and at ViroPharma's
          expense, (a) provide Wyeth with advice and reasonable assistance in
          (i) developing a Regulatory Approval filing strategy for Products,
          (ii) reviewing study reports from clinical trials of Products, (iii)
          preparing applications for Regulatory Approval for Products, (iv)
          preparing supplements to applications for Regulatory Approval for
          Products, (v) responding to questions from Regulatory Authorities
          regarding applications for Regulatory Approval or any supplement
          thereto and (b) participate in interactions with Regulatory
          Authorities concerning the Products.

     5.4  Regulatory Reporting. Wyeth shall be responsible for filing all
          reports required to be filed in order to maintain any Regulatory
          Approvals granted for Products in the world, including, without
          limitation, adverse drug experience reports. ViroPharma shall
          cooperate with Wyeth in preparing and filing all such reports and,
          upon Wyeth's request, provide Wyeth with any information in
          ViroPharma's possession or Control which Wyeth reasonably deems to be
          relevant to any such reports. Notwithstanding the foregoing, to the
          extent ViroPharma has or receives any information regarding any
          adverse drug experience which may be related to the use of any
          Product, ViroPharma shall promptly provide Wyeth with all such
          information in accordance with the Adverse Event Reporting Procedures
          (as may be amended from time to time upon mutual agreement of the
          Parties) set forth in Exhibit 5.4 attached hereto. Expenses (both
          internal expenses and out-pocket costs paid to a Third Party) incurred
          by a Party in performing its regulatory reporting obligations under
          this Section 5.4 in connection with Regulatory Approvals in the
          Copromotion Territory shall be charged by such Party to such Party's
          Marketing Account for such Product as a Post-Approval Research and
          Regulatory Expense. Wyeth shall be solely responsible for expenses
          incurred by it in performing its regulatory reporting obligations
          under this Section 5.4 in connection with Regulatory Approvals in the
          Wyeth Territory.

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6.   COMMERCIALIZATION OF PRODUCTS.

     6.1  Commercialization in the Copromotion Territory.

          6.1.1  Principles of Copromotion. Pursuant to the licenses granted to
                 Wyeth in Section 2, Wyeth shall have the exclusive right to
                 Commercialize each Product in the Field in the Copromotion
                 Territory during the term of this Agreement. Notwithstanding
                 the foregoing, ViroPharma, subject to this Section 6.1 and
                 Section 11.6, shall have the right to Promote each Product,
                 jointly with Wyeth, in the Copromotion Territory, using
                 professional sales representatives that are full time employees
                 of ViroPharma or that are employees of Contract Sales
                 Organizations ("CSOs"). The Parties' marketing activities shall
                 comply with the terms of this Agreement and the Copromotion
                 Territory Commercialization Plan.

          6.1.2  Commercialization Plan. On a Product by Product basis, not
                 later than sixty (60) days after the filing of the first
                 application for Regulatory Approval of a Product in the
                 Copromotion Territory, the MSC shall prepare and approve a
                 rolling multiyear (not less than three (3) years) plan for
                 Commercializing such Product in the Copromotion Territory (the
                 "Copromotion Territory Commercialization Plan"), which plan
                 includes a comprehensive market development, marketing, sales,
                 supply and distribution strategy for such Product in the
                 Copromotion Territory. The Copromotion Territory
                 Commercialization Plan shall be updated by the MSC at least
                 once each calendar year such that it addresses no less than the
                 three (3) upcoming years. Not later than thirty (30) days after
                 the filing of the first application for Regulatory Approval of
                 a Product in the Copromotion Territory and thereafter on or
                 before September 30 of each calendar year, the MSC shall
                 prepare an annual commercialization plan and budget (the
                 "Annual Commercialization Plan and Budget"), which plan is
                 based on the then current Copromotion Territory
                 Commercialization Plan and includes a comprehensive market
                 development, marketing, sales, supply and distribution
                 strategy, including an overall budget for anticipated
                 marketing, promotion and sales efforts in the upcoming calendar
                 year (the first such Annual Development Plan and Budget shall
                 cover the remainder of the calendar year in which such Product
                 is anticipated to be approved plus the first full calendar year
                 thereafter). The Annual Commercialization Plan and Budget will
                 specify which Target Markets and distribution channels each
                 Party shall devote its respective Promotion efforts towards,
                 the personnel and other resources to be devoted by each Party
                 to such efforts, the number and positioning of Details to be
                 performed by each Party, as well as market and sales forecasts
                 and related operating expenses, for the Product in each country
                 of the Copromotion Territory, and budgets for projected
                 Pre-Marketing

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                 Expenses, Sales and Marketing Expenses and Post-Approval
                 Research and Regulatory Expenses. In preparing and updating the
                 Copromotion Territory Commercialization Plan and each Annual
                 Commercialization Plan and Budget, the MSC will take into
                 consideration factors such as market conditions, regulatory
                 issues and competition.

          6.1.3  Allocation of Target Markets; Sales Effort. On a Product by
                 Product basis, at least ninety (90) days before the launch of
                 such Product in a country of the Copromotion Territory and
                 thereafter, at least ninety (90) days before the beginning of
                 each calendar year, the MSC ************* in such country and
                 ****************** on the following criteria and conditions:

                 (a)  each *************** in each country of the Copromotion
                      Territory shall, as much as is reasonably possible,
                      ***************** for such Product expected to be made in
                      such country of the Copromotion Territory in accordance
                      with the **************************** for the Promotion of
                      such Product in such country;

                 (b)  the inclusion of ***********************************;

                 (c)  Wyeth's aggregate **********************************; and

                 (d)  the MSC may not, without the prior written consent of the
                      President of ViroPharma,********************************.

                 The number of Details assigned to a Party by the MSC in
                 accordance with this Section 6.1.3 shall be such Party's
                 ***************************.

          6.1.4  Incremental Sales Force Effort. If a Party is asked by the MSC
                 to deliver more sales force effort than that which is agreed by
                 the Parties to be more than a 50/50 selling effort in any
                 Calendar Quarter, and if such Party provides such increased
                 sales force effort (the "Incremental Sales Force Effort"), such
                 Party shall be entitled to charge the cost of the Incremental
                 Sales Force Effort to such Party's Marketing Account as an
                 Incremental Sales Force Effort Expense. The cost to be so
                 charged shall be at a rate approved by the MSC at the time such
                 Incremental Sales Force Effort is requested and shall be on a
                 cost per Detail basis. If Wyeth is the Party providing the
                 Incremental Sales Force Effort, Wyeth shall be reimbursed for
                 its Incremental Sales Force Expense by deducting the
                 Incremental Sales Force Expense incurred for such Calendar
                 Quarter from the Net Sales of such Product sold during such
                 Calendar Quarter prior to the allocation of Net Profits for
                 such Calendar Quarter. If ViroPharma is the Party providing the
                 Incremental Sales Force Effort, Wyeth shall reimburse
                 ViroPharma for its Incremental Sales Force Expense by

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                 deducting such Incremental Sales Force Expense from the Net
                 Sales of such Product sold during such Calendar Quarter prior
                 to the allocation of Net Products for such Calendar Quarter and
                 distributing such deducted amount to ViroPharma simultaneously
                 with the distribution of Net Profits to ViroPharma for such
                 Calendar Quarter. The Party incurring the Incremental Sales
                 Force Expense shall report the same to the other Party as part
                 of the reports submitted under Section 6.1.8(d).

          6.1.5  Extra Effort. If a Party expends more effort than originally
                 required of it by the Copromotion Territory Commercialization
                 Plan in order to perform Details that were part of the other
                 Party's Assigned Sales Force Effort, and that the other Party
                 fails to perform and which additional effort is approved in
                 advance by the MSC ("Extra Effort"), the first Party shall be
                 entitled to charge the costs of the Extra Effort ("Extra Effort
                 Expense") to its Marketing Account on a cost per Detail basis
                 consistent with Section 6.1.8(d), as well as twelve percent
                 (12%) annual interest, compounded monthly, accrued on the
                 amount charged for the period in which the Extra Effort is
                 expended. If Wyeth is the Party providing the Extra Effort,
                 Wyeth shall be reimbursed for its Extra Effort Expense by
                 deducting the Extra Effort Expense incurred for such Calendar
                 Quarter from the Net Sales of such Product sold during such
                 Calendar Quarter before the allocation of Net Profits for such
                 Calendar Quarter. If ViroPharma is the Party providing the
                 Extra Effort, Wyeth shall reimburse ViroPharma for its Extra
                 Effort Expense by deducting such Extra Effort Expense from the
                 Net Sales of such Product sold during such Calendar Quarter
                 before the allocation of Net Products for such Calendar Quarter
                 and distributing such deducted amount to ViroPharma
                 simultaneously with the distribution of Net Profits to
                 ViroPharma for such Calendar Quarter. The Party incurring the
                 Extra Effort Expense shall report the same to the other Party
                 as part of the reports submitted under Section 6.1.8(d).

          6.1.6  Performance Metrics. The **************************** or as
                 part of any ******************* shall be determined according
                 to Detail reporting mechanisms and methodology that are
                 approved and applied consistently by the MSC.

          6.1.7  Sales and Distribution; Recalls. During the term of this
                 Agreement, Wyeth shall be responsible for:

                 (a)  distribution of all Products in the Copromotion Territory
                      hereunder, the booking of all sales with respect to such
                      Products and the performance of related services. If
                      ViroPharma receives any order for the Product in the
                      Copromotion Territory during the term of this Agreement,
                      it shall promptly refer such orders to Wyeth.

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                 (b)  handling and implementing all recalls and market
                      withdrawals of any Product in the Copromotion Territory.
                      ViroPharma will make available to Wyeth, upon request, all
                      of ViroPharma's pertinent records that Wyeth may
                      reasonably request to assist it in effecting any recall or
                      market withdrawals. Except as expressly otherwise provided
                      below in this Section 6.1.7(b), the Parties shall share
                      equally all other costs of a recall or marketing
                      withdrawal of a Product in the Co-Promotion Territory.
                      Notwithstanding the foregoing, a Party shall bear any and
                      all costs of a recall or market withdrawal of a Product in
                      the Co-Promotion Territory to the extent such recall or
                      market withdrawal results from a negligent act or omission
                      or intentional misconduct on the part of such Party,
                      including, without limitation, the breach of any of such
                      Party's warranties under Sections 10.3(d) or 10.3(e)
                      hereof, and not from a negligent act or omission or
                      intentional misconduct on the part of the other Party. A
                      Party shall have no obligation to reimburse or otherwise
                      compensate the other Party for any lost profits or income
                      that may arise in connection with any such recall or
                      market withdrawal.

                 (c)  handling all aspects of order processing, invoicing and
                      collection, inventory and receivables.

                 (d)  providing customer support, including handling medical
                      queries, and performing other functions consistent with
                      consumer practice for pharmaceutical products consistent
                      with the then current Copromotion Territory
                      Commercialization Plan and the applicable Annual
                      Commercialization Plan and Budget.

          6.1.8  Commercialization Expenses.

                 (a)  Pre-Marketing Expenses. On a Product by Product and
                      country by country basis, before Regulatory Approval of
                      such Product in such country of the Copromotion Territory,
                      the Pre-Marketing Expenses incurred by the Parties with
                      respect to such Product in anticipation of obtaining
                      Regulatory Approval of such Product in such country shall
                      *****************************. As such Pre-Marketing
                      Expenses are incurred they shall be paid for by the Party
                      incurring such expenses, subject to reimbursement as set
                      forth in Section 6.1.8(g).

                 (b)  Sales and Marketing Expenses. On a Product by Product and
                      country by country basis, after Regulatory Approval of
                      such Product in such country of the Copromotion Territory,
                      the Sales and Marketing Expenses incurred by the Parties
                      shall **********************. The costs of a Party's
                      professional

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<PAGE>

                      sales representatives and marketing personnel
                      ***********************************.

                 (c)  Post-Approval Research and Regulatory Expenses. On a
                      Product by Product and country by country basis, after
                      Regulatory Approval of such Product in such country of the
                      Copromotion Territory, the Post-Approval Research and
                      Regulatory Expenses incurred by the Parties in connection
                      with such Product in such country shall
                      *************************.

                 (d)  Payment of Expenses; Marketing Accounts. Subject to
                      reconciliation as provided in Sections 6.1.8(f) or
                      6.1.8(g), as applicable, **************************.
                      Subject to the limitations set forth in Section 6.1.8(e),
                      each Party shall charge all such expenses so incurred by
                      it or its Affiliates to a separate account created by such
                      Party on its books and records solely for the purpose of
                      tracking expenses incurred in connection with the
                      marketing, Promotion, distribution and sale of Products in
                      the Copromotion Territory (each, a "Marketing Account").
                      Within thirty (30) days after the end of each Calendar
                      Quarter, each Party shall submit to the other Party a
                      written summary of all Pre-Marketing Expenses, Sales and
                      Marketing Expenses, Post-Approval Research and Regulatory
                      Expenses, Incremental Sales Force Expenses and Extra
                      Effort Expenses incurred by it in performing its
                      obligations in connection with the marketing, Promotion,
                      distribution and sale of Products in the Copromotion
                      Territory, charged to its Marketing Account during such
                      Calendar Quarter, which summary shall be accompanied by
                      reasonable supporting documentation for such expenses.

                 (e)  Expense Limitations. The Pre-Marketing Expenses, Sales and
                      Marketing Expenses and Post-Approval Research and
                      Regulatory Expenses charged by either Party to its
                      Marketing Account in accordance with this Section 6.1.8,
                      shall not be in amount in excess of *********************
                      of the amount included for such expenses in the then
                      current Annual Commercialization Plan and Budget, unless
                      the MSC approves such excess expenses. All payments made
                      by a Party to any Third Party in connection with the
                      performance of its obligations in connection with the
                      Commercialization of a Product in the Copromotion
                      Territory shall be charged to such Party's Marketing
                      Account at such Party's actual out-of-pocket cost incurred
                      in accordance with the MSC approved contract entered into
                      with such Third Party.

                 (f)  Reconciliation of Pre-Marketing Expenses. Within sixty
                      (60) days after the end of each Calendar Quarter, Wyeth
                      shall prepare a

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                      reconciliation report, accompanied by reasonable
                      supporting documentation and calculations, which
                      reconciles the Pre-Marketing Expenses charged to each
                      Party's Marketing Account during such Calendar Quarter
                      pursuant to this Section 6.1.8 and the share of the
                      Parties' aggregate Pre-Marketing Expenses to be allocated
                      to each of the Parties for such Calendar Quarter in
                      accordance with this Section 6.1.8. Within thirty (30)
                      days after Wyeth delivers such reconciliation report to
                      ViroPharma, ***********************************. If, with
                      respect to any Calendar Quarter, ViroPharma has a
                      Pre-Marketing Expense Shortfall for which it is to
                      reimburse Wyeth and ViroPharma is unable or otherwise
                      fails to pay to Wyeth all or part of the Pre-Marketing
                      Expense Shortfall before the end of the thirty (30) day
                      period required by this Section 6.1.8(f), the unpaid
                      portion of the Pre-Marketing Shortfall would accumulate
                      interest at the annual interest rate of twelve percent
                      (12%), compounded monthly, and would be combined with any
                      R&D Shortfall and repaid to Wyeth in accordance with
                      Section 4.6.5.

                 (g)  Reimbursement of Sales and Marketing Expenses and
                      Post-Approval Research and Regulatory Expenses. At the
                      time Wyeth, pursuant to Section 7.6.3, distributes to
                      ViroPharma, ViroPharma's share of

                      Net Profits obtained from the sale of a Product in a
                      country of the Copromotion Territory during any Calendar
                      Quarter, Wyeth shall also reimburse each of Wyeth and
                      ViroPharma for those Sales and Marketing Expenses,
                      Post-Approval Research and Regulatory Expenses,
                      Incremental Sales Force Effort Expenses, and Extra Effort
                      Expenses that are (i) directly allocable to the
                      Commercialization of such Product in such country during
                      such Calendar Quarter (ii) properly charged by such Party
                      to its Marketing Account and (iii) reported to the other
                      Party in accordance with this Section 6.1.8. Such
                      reimbursements shall be made solely from revenues obtained
                      by Wyeth which are attributable to the Net Sales of such
                      Product in such country of the Copromotion Territory,
                      **********************************. If the Net Sales
                      ***************************************** shall be carried
                      over on such Party's Marketing Account into subsequent
                      Calendar Quarters *****************************.

          6.1.9  Marketing and Promotional Materials. The MSC shall determine
                 the content, quantity and method of distribution of any
                 promotional materials related to the Product in the Copromotion
                 Territory, provided, however, that all such marketing and
                 promotional materials shall be subject to the approval of
                 Wyeth's and ViroPharma's legal, medical affairs, marketing and
                 regulatory affairs department before any use thereof by either
                 Party. Wyeth will be responsible for preparing and duplicating
                 such marketing

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<PAGE>

                 and promotional materials and shall provide reasonable
                 quantities of the same to ViroPharma for use by ViroPharma in
                 connection with its Promotion of the Product in the Copromotion
                 Territory hereunder. Each Party shall use only marketing and
                 promotional materials approved by the MSC and provided by
                 Wyeth. All copyright and other intellectual property rights in
                 said promotional materials shall remain vested in Wyeth.
                 Neither Party may not independently create, distribute or use
                 sales, promotion or other similar material relating to a
                 Product in the Copromotion Territory without the prior written
                 consent of either the MSC or the other Party.

          6.1.10 Promotional Claims. Each Party shall limit the claims of safety
                 and efficacy that such Party or its sales force makes for a
                 Product in the Copromotion Territory to those that are
                 consistent with the approved labeling for such Product in such
                 country of the Copromotion Territory. Neither Party may add,
                 delete or modify claims of efficacy or safety in its Promotion
                 of any Product in the Copromotion Territory nor make any
                 changes in Promotion materials and literature approved by the
                 MSC. Each Party's Detailing and Promotion of a Product in the
                 Copromotion Territory shall be in strict adherence to all
                 regulatory, professional and legal requirements including,
                 without limitation, FDA's regulations and guidelines concerning
                 the advertising of prescription drug products, the American
                 Medical Association's Guidelines on Gifts to Physicians, the
                 PhRMA Guidelines for Marketing Practices, the ACCME Standards
                 for Commercial Support of Continuing Medical Education, the
                 then current Copromotion Territory Commercialization Plan for
                 the Product and any updates thereto.

          6.1.11 Samples. When Detailing and Sampling the Product, each Party's
                 professional sales representative shall complete Sample Receipt
                 Forms provided by Wyeth. A copy of the completed Sample Receipt
                 Forms shall be left with the Physician receiving the Detail.
                 Such professional sales representative shall mail to Wyeth, in
                 pre-addressed, postage-paid envelopes provided by Wyeth, at the
                 close of each business day the original completed Sample
                 Receipt Forms for all Details performed by such professional
                 sales representative that day. A copy of all such Sample
                 Receipt Forms shall be kept by each such professional sales
                 representative. Each Party shall ensure that each of its
                 professional sales representatives fills out the Sample Receipt
                 Forms accurately, completely and timely. The Fully-Absorbed
                 Standard Cost incurred by Wyeth in providing and processing
                 Sample Receipt forms shall be charged by Wyeth to its Marketing
                 Account as a Sales and Marketing Expense.

          6.1.12 Communications. Each Party shall be fully responsible for
                 disseminating accurate information regarding a Product to its
                 professional sales

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                   representatives based on the Product's approved labeling and
                   information provided by the MSC.

           6.1.13  Training. Each Party shall be responsible for the training of
                   its own professional sales representatives, in accordance
                   with the training requirements and training programs and
                   using training materials approved by the MSC and shall
                   require each of its professional sales representatives to
                   attend sales training for a Product before their Promotion of
                   such Product in the Copromotion Territory hereunder. After
                   the initial training meeting, each Party shall periodically
                   provide additional training, in accordance with the training
                   requirements and training programs and using training
                   materials approved by the MSC, to each of its professional
                   sales representatives Promoting Products hereunder. At the
                   discretion and upon approval of the MSC, any such training
                   meetings may be held jointly by the Parties. The expenses
                   incurred by each Party in training its professional sales
                   representatives before the launch of a Product shall be
                   charged to such Party's Marketing Account as a Pre-Marketing
                   Expense. The expenses incurred by each Party in training its
                   professional sales representatives after the launch of a
                   Product shall be charged to such Party's Marketing Account as
                   a Sales and Marketing Expense.

           6.1.14  Compliance. In connection with its Promotion of the Product
                   in the Copromotion Territory, each Party shall comply and
                   shall cause each of its employees, representatives and
                   agents, including, without limitation, each of its
                   professional sales representatives, to comply with all laws
                   and regulations of the Copromotion Territory and shall do
                   nothing which such Party knows or reasonably should know
                   would jeopardize the goodwill or reputation of either Party
                   or the reputation of any Product.

           6.1.15  Generic Product. On a Product by Product and country by
                   country (within the Copromotion Territory) basis, no later
                   than three (3) years before the expiration of the last to
                   expire of the Patent Rights conferring market exclusivity for
                   such Product in such country of the Copromotion Territory,
                   the Parties will determine by mutual agreement after good
                   faith discussions whether to jointly launch a generic version
                   of such Product in the Copromotion Territory and what the
                   terms and conditions regarding such Product will be. If the
                   Parties, on or before such time, are unable to agree to
                   jointly launch such a generic Product in such country, then
                   upon expiration of the relevant Patent Rights in such
                   country, and notwithstanding any other exclusive or
                   non-exclusive license granted under this Agreement, each
                   Party shall have the right and license to utilize the
                   Collaboration Technology and the other Party's Know-How
                   solely to the extent necessary to launch and Commercialize
                   its own generic version of such Product in such country and
                   thereafter shall have no further obligations to the other
                   Party with respect to such generic Product.

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         6.2      Commercialization in the Wyeth Territory. Wyeth shall have the
                  sole right, either directly or through its Affiliates,
                  sublicensees and/or distributors, to market, distribute and
                  sell Products in the Wyeth Territory. Wyeth shall use its
                  Commercially Reasonable Efforts to sell each Product in those
                  countries of the Wyeth Territory for which Wyeth has obtained
                  Regulatory Approval for such Product. Wyeth shall be
                  responsible for all marketing and selling expenses for the
                  sale of Products in the Wyeth Territory and Wyeth shall have
                  the sole right and discretion to determine the price of
                  Products sold in the Wyeth Territory and to make all other
                  business decisions concerning the Commercialization of
                  Products in the Wyeth Territory.

7.       CONSIDERATION; PROFIT SHARING.

         7.1      Research Program Expense Reimbursements. Wyeth agrees to
                  provide ViroPharma
                  **********************************************************:

                  (a)  Wyeth shall pay a nonrefundable fee of five million
                       dollars ($5,000,000.00) to ViroPharma on the first
                       business day after the Effective Date in consideration of
                       ViroPharma's agreement to participate in the JSC,
                       including the preparation, updating and implementation of
                       the Global Research and Development Plan and the Annual
                       Development Plans and Budgets; and

                  (b)  Wyeth shall reimburse ViroPharma for up to
                       *********************** of ViroPharma's
                       *****************************************. Wyeth shall
                       create on its books and records an
                       ******************************** for this purpose, which
                       ********************************************************,
                       but shall be subject to adjustment, from time to time, by
                       ViroPharma's election to offset a portion of any R&D
                       Shortfall against the R&D Reimbursement Account, as
                       provided in Section 4.6.5.

         7.2      Additional Development Expense Payments. Wyeth shall pay to
                  ViroPharma the following additional development expense
                  payments, each such payment being due and payable within
                  thirty (30) days after the occurrence of the corresponding
                  event:

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<PAGE>

<TABLE>
<CAPTION>
                        <S>                                              <C>
                        --------------------------------------------------------------------------------
                                 *********                                  ***************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

                        --------------------------------------------------------------------------------
                        ****************************                     ********************

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</TABLE>

                  Each of the additional development expense payments set forth
                  above shall be payable one time only ************************,
                  except in the case of the additional development expense
                  payments payable for ********************, which additional
                  development expense payments shall be payable with respect to
                  *******************************, provided, however, that, with
                  respect to any Product that *********************************,
                  the receipt of *****************************************,
                  shall not result in
                  ********************************************.

                  If, with respect to any Product, any of the above events
                  *********************** does not occur because the JSC
                  determines that
                  ************************************************, such event
                  will be

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<PAGE>

                 deemed to have occurred on the date the JSC makes such a
                 determination for purposes of determining
                 ***********************************. Additionally, if certain
                 of the above stated events occur
                 ********************************, if such later events occur in
                 connection with the subsequent Development of another Product
                 hereunder,
                 *****************************************************. For
                 example,
                 **************************************************************.

         7.3     Purchase of Equity. On the Effective Date, Wyeth and ViroPharma
                 shall enter into the Stock Purchase Agreement attached to this
                 Agreement as Exhibit 7.3, pursuant to which Wyeth shall
                 purchase, and ViroPharma will sell to Wyeth, shares of the
                 capital stock of ViroPharma on the terms and conditions set
                 forth therein.

         7.4     Royalties.

                 7.4.1     Royalty Rates. In consideration for the licenses
                           granted to Wyeth under Section 2.1 hereof, Wyeth, on
                           a Product by Product and calendar year by calendar
                           year basis, will pay to ViroPharma royalties based on
                           Net Sales obtained by Wyeth or its Affiliates from
                           the sale of such Product in the Wyeth Territory,
                           which royalties shall be calculated as follows:

                                   royalty = A + B + C, where:

                                   A  =  either (i) for  ***************  of
                                         the portion of Wyeth's and its
                                         Affiliates' Net Sales obtained from the
                                         sale of such ********** in the Wyeth
                                         Territory (excluding Net Sales obtained
                                         from the sale of such Product in any
                                         countries where the obligation to pay
                                         royalties under this Section 7.4.1 has
                                         expired in accordance with Section
                                         7.4.3 with respect to such Product),
                                         which, during the calendar year in
                                         question are less than or equal
                                         ********************, or (ii) for
                                         ************************** of the
                                         portion of Wyeth's and its Affiliates'
                                         Net Sales obtained from the sale of
                                         such ******************* in the Wyeth
                                         Territory (excluding Net Sales obtained
                                         from the sale of such Product in any
                                         countries where the obligation to pay
                                         royalties with under this Section 7.4.1
                                         has expired in accordance with Section
                                         7.4.3 with respect to such Product)
                                         which, during the calendar year in
                                         question are less than or equal to
                                         **************************************;

                                   B  =  either (i) for
                                         ***************************** of the
                                         portion of Wyeth's and its Affiliates'
                                         Net Sales obtained from the sale of
                                         such ************ in the Wyeth
                                         Territory (excluding Net Sales obtained
                                         from the sale of such

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                                          Product in any countries where the
                                          obligation to pay royalties with
                                          under this Section 7.4.1 has expired
                                          in accordance with Section 7.4.3
                                          with respect to such Product),
                                          which, during the calendar year in
                                          question are greater than
                                          ***************************** and
                                          less than or equal to
                                          ****************************, or
                                          (ii) for *************************
                                          of the portion of Wyeth's and its
                                          Affiliates' Net Sales obtained from
                                          the sale of such
                                          ********************** in the Wyeth
                                          Territory (excluding Net Sales
                                          obtained from the sale of such
                                          Product in any countries where the
                                          obligation to pay royalties with
                                          under this Section 7.4.1 has expired
                                          in accordance with Section 7.4.3
                                          with respect to such Product),
                                          which, during the calendar year in
                                          question are greater
                                          *************************************;
                                          and

                                   C  =   either (i) for
                                          ************************************
                                          of the portion of Wyeth's and its
                                          Affiliates' Net Sales obtained from
                                          the sale of such ******************
                                          in the Wyeth Territory (excluding
                                          Net Sales obtained from the sale of
                                          such Product in any countries where
                                          the obligation to pay royalties with
                                          under this Section 7.4.1 has expired
                                          in accordance with Section 7.4.3
                                          with respect to such Product),
                                          which, during the calendar year in
                                          question are greater than
                                          ************************ or (ii) for
                                          ***************************** of the
                                          portion of Wyeth's and its
                                          Affiliates' Net Sales obtained from
                                          the sale of such
                                          *************************** in the
                                          Wyeth Territory (excluding Net Sales
                                          obtained from the sale of such
                                          Product in any countries where the
                                          obligation to pay royalties with
                                          under this Section 7.4.1 has expired
                                          in accordance with Section 7.4.3
                                          with respect to such Product),
                                          which, during the calendar year in
                                          question are greater than
                                          *************************************.

                           ViroPharma acknowledges and agrees that nothing in
                           this Agreement (including, without limitation, any
                           exhibits or attachments hereto) shall be construed as
                           representing an estimate or projection of either (i)
                           the number of Class A Products and/or Class B
                           Products that will or may be successfully developed
                           and/or commercialized or (ii) anticipated sales or
                           the actual value of the ViroPharma Technology, and
                           Compound or any Product and that the figures set
                           forth in this Section 7.4 or elsewhere in this
                           Agreement or that have otherwise been discussed by
                           the Parties are merely intended to define Wyeth's
                           royalty obligations to ViroPharma in the event such
                           sales performance is achieved. Wyeth MAKES NO
                           REPRESENTATION OR WARRANTY, EITHER EXPRESS OR

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<PAGE>

                           IMPLIED, THAT IT WILL BE ABLE TO SUCCESSFULLY DEVELOP
                           AND/OR COMMERCIALIZE ANY PRODUCT OR, IF
                           COMMERCIALIZED THAT ANY IT WILL ACHIEVE ANY
                           PARTICULAR SALES LEVEL OF SUCH PRODUCT(S).

                  7.4.2    Royalty Adjustments. For each Product sold in each
                           country of the Wyeth Territory in each Calendar
                           Quarter, the royalties payable to ViroPharma,
                           pursuant to Section 7.4.1 and/or, if applicable,
                           Section 11.5 or 11.6, for the Net Sales of such
                           Product in such country during such Calendar Quarter
                           may be reduced as set forth below, provided, however,
                           that in no event will such royalties in any country
                           be reduced by more than ************** by reason of
                           the adjustments set forth below:

                           (a)      Unpatented Products. If in a given Calendar
                                    Quarter during the Full Royalty Rate Period,
                                    neither of Section 1.49(a) or (b) continues
                                    to be true because one or more of Valid
                                    Claims are invalidated in such country, the
                                    royalties payable to ViroPharma, pursuant to
                                    Section 7.4.1 and/or, if applicable, Section
                                    11.5 or 11.6, for the Net Sales of such
                                    Product in such country during such Calendar
                                    Quarter shall be reduced to
                                    ********************* of the applicable
                                    marginal rate set forth in Section 7.4.1
                                    and/or, if applicable, Section 11.5 or 11.6.
                                    To calculate such reduced royalty amount in
                                    such countries, Net Sales will be allocated
                                    among the royalty increments in Sections
                                    7.4.1, 11.5 and/or 11.6, as applicable,
                                    based on
                                    ********************************************
                                    *********.

                           (b)      Competition. If Competition (as defined
                                    below in this Section 7.4.2 (b)) exists
                                    during a given Calendar Quarter with respect
                                    to a Product in any country, the royalties
                                    payable to ViroPharma, pursuant to Section
                                    7.4.1 and/or, if applicable, Section 11.5 or
                                    11.6, for the Net Sales of such Product in
                                    such country during such Calendar Quarter
                                    shall be reduced to ************************
                                    of the applicable marginal rate set forth in
                                    Section 7.4.1 and/or, if applicable, Section
                                    11.5 or 11.6. To calculate such reduced
                                    royalty amount when Competition exists in
                                    such countries, Net Sales will be allocated
                                    among the royalty increments in Sections
                                    7.4.1, 11.5 and/or 11.6, as applicable,
                                    based on ************************. For
                                    purposes of this Section 7.4.2(b),
                                    Competition shall be deemed to exist if,
                                    during the applicable Calendar Quarter, on a
                                    Product by Product and country by country
                                    basis, (i) one or more Third Parties is
                                    selling a pharmaceutical product for use in
                                    the Field containing as an active
                                    ingredient, the Compound that is an active
                                    ingredient in the Product being sold by or
                                    on behalf of Wyeth, its Affiliates or
                                    sublicensees in such country; and (ii) the
                                    sales of such competing products (measured
                                    on a unit basis) accounts for ************
                                    or

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<PAGE>

                                    more of the total market in such country.
                                    The total market in such country shall be
                                    the sum of (x) the number of units of the
                                    affected Product sold by Wyeth, its
                                    Affiliates or sublicensees in such country
                                    during such Calendar Quarter and (y) the
                                    number of units of competing products sold
                                    by parties other than Wyeth, its Affiliates
                                    or sublicensees in such country during such
                                    Calendar Quarter.

                  7.4.3    Term of Royalty. The royalties payable pursuant to
                           Section 7.4.1 and, if applicable, pursuant to Section
                           11.5 or 11.6, as adjusted pursuant to Section 7.4.2,
                           will be payable on a country by country and Product
                           by Product basis during the Full Royalty Rate Period.
                           During the Reduced Royalty Rate Period for a Product,
                           Wyeth shall have an exclusive license, except as
                           otherwise provided under this Agreement, to use the
                           ViroPharma Know-How in the Field and ViroPharma's
                           interest in any Collaboration Know-How in the Field,
                           to make, have made, use, import, offer to sell and
                           sell such Product in such country. In consideration
                           of such license, Wyeth shall pay to ViroPharma a
                           royalty in the amount of three percent (3%) of the
                           Net Sales obtained from the sale by Wyeth and its
                           Affiliates of such Product in such country, which
                           royalty shall be payable only for sales made during
                           the Reduced Royalty Rate Period. On a country by
                           country basis, upon expiration of the Reduced Royalty
                           Rate Period, the license granted to Wyeth with
                           respect to such country under this Section 7.4.3
                           shall continue to be a perpetual license which
                           thereafter shall become irrevocable, fully-paid and
                           royalty-free license, exclusive except for the
                           license granted pursuant to Section 6.1.15.

         7.5      Profit Split Payments.

                  7.5.1    Baseline Allocation of Profits. In consideration for
                           ViroPharma's provision of services in connection with
                           the Promotion of Products in the Copromotion
                           Territory pursuant to Section 6.1, Wyeth, on a
                           country by country basis, shall pay to ViroPharma
                           *********************** of the Net Profits obtained
                           from the sale of a Product in such country of the
                           Co-Promotion Territory, which percentage may be
                           adjusted from time to time in accordance with Section
                           7.5.3, (the most recently updated and adjusted
                           allocation, ViroPharma's "Baseline Allocation of Net
                           Profits") which payment shall be made to ViroPharma
                           at the times and in the manner set forth in Section
                           7.6.3. Wyeth shall retain the remaining portion of
                           Net Profits (Wyeth's "Baseline Allocation of Net
                           Profits"). Notwithstanding the foregoing, in any
                           Penalty Year, the allocation of Net Profits will be
                           adjusted in accordance with Section 7.5.2.

                  7.5.2    Temporary Adjustments to Distribution of Profits. In
                           a Penalty Year, each Party will be allocated a
                           portion of Net Profits which allocation will be made
                           based on the following formula:

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                                   *********************************

                         where
                         ******************************************************.

                  7.5.3  Permanent Adjustment to Baseline Allocation of Profits.
                         If a Party incurs *************************, and the
                         other Party incurs no Lapse Year during this period,
                         then the Party incurring no Lapse Years may, at its
                         discretion, impose a permanent change in the Baseline
                         Allocation of Net Profits established in Section 7.5.1.
                         The new Baseline Allocation of Profits shall be
                         equivalent to the average proportion of Net Profits
                         received by such Party during the ********************
                         and shall become effective on January 1 of the year
                         following the
                         ********************************************. Examples
                         of the calculation of the distribution of Net Profits
                         during Penalty Years and the imposition of new baseline
                         distributions are set forth in Exhibit 7.5.3.

                  7.5.4  Term of Profit Split Payments. With respect to a
                         Product, Wyeth, on a country by country basis in the
                         Copromotion Territory, shall pay to ViroPharma a
                         portion of Net Profits obtained from the sale of such
                         Product in such country of the Copromotion Territory as
                         set forth in Section 7.5.1 for so long as both Parties
                         are Promoting such Product in such country pursuant to
                         this Agreement.

         7.6      Reports and Payments.

                  7.6.1  Cumulative Royalties. The obligation to pay royalties
                         under this Agreement shall be imposed only once with
                         respect to a single unit of a Product regardless of how
                         many Valid Claims included within the Patent Rights
                         would, but for this Agreement, be infringed by the
                         manufacture, use, import, offer for sale or sale of
                         such Product in the country of such manufacture, use or
                         sale.

                  7.6.2  Royalty Statements and Payments. Wyeth, within sixty
                         (60) days after the end of each Calendar Quarter shall
                         deliver to ViroPharma a report setting forth for such
                         Calendar Quarter the following information, on a
                         Product by Product basis, with respect to Products sold
                         in the Wyeth Territory, (a) the Net Sales of such
                         Product in the Wyeth Territory, (b) the basis for any
                         adjustments to the royalty payable for the sale of such
                         Product, and (c) the royalty due hereunder for the sale
                         of such Product. No such reports shall be due for any
                         Product before the First Commercial Sale of such
                         Product in the Wyeth Territory. The total royalty due
                         for the sale of Products during such Calendar Quarter
                         less any deductions made in accordance with Section
                         4.6.5 shall be remitted at the time such report is
                         made.

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                  7.6.3    Net Profit Statements and Payments.

                           (a)      Estimated Statements. Within the later of
                                    (i) thirty (30) days after the end of each
                                    Calendar Quarter or (ii) fifteen (15) days
                                    beyond the date on which Wyeth receives from
                                    ViroPharma the report required under Section
                                    6.1.8(d) with respect to such Calendar
                                    Quarter, Wyeth shall deliver to ViroPharma a
                                    report setting forth the following estimated
                                    information with respect to Products sold in
                                    the Copromotion Territory during such
                                    Calendar Quarter: (i) the Net Sales of such
                                    Product in each country of the Copromotion
                                    Territory, (ii) the Net Profits obtained
                                    from the sale of such Product in each
                                    country of the Copromotion Territory, (iii)
                                    the deductions made from Net Sales in
                                    calculating such Net Profits, including,
                                    without limitation, the computation of Cost
                                    of Goods Manufacture for Sale, each Party's
                                    Sales and Marketing Expenses, Incremental
                                    Sales Force Expenses, if any, Extra Effort
                                    Expenses, if any, and Post-Approval Research
                                    and Regulatory Expenses, and (iv) the amount
                                    of Net Profits to be allocated to each
                                    Party, including an explanation of any
                                    deviation from the Baseline Allocation of
                                    Net Profits made in accordance with Section
                                    7.5.1. No such reports shall be due with
                                    respect to any Product before the First
                                    Commercial Sale of such Product in the
                                    Copromotion Territory.

                           (b)      Actual Statements. After the First
                                    Commercial Sale of a Product in the
                                    Copromotion Territory, Wyeth, within sixty
                                    (60) days after the end of each Calendar
                                    Quarter, shall deliver to ViroPharma a
                                    report setting forth for such Calendar
                                    Quarter the following information, on a
                                    Product by Product and Country by Country
                                    basis: (i) the Net Sales of such Product in
                                    each country of the Copromotion Territory,
                                    (ii) the Net Profits obtained from the sale
                                    of such Product in each country of the
                                    Copromotion Territory, (iii) the deductions
                                    made from Net Sales in calculating such Net
                                    Profits, including, without limitation, the
                                    computation of Cost of Goods Manufactured
                                    for Sale in such detail as Wyeth customarily
                                    uses for its own internal reporting
                                    purposes, or as reasonably requested by
                                    ViroPharma, each Party's Sales and Marketing
                                    Expenses, Incremental Sales Force Expenses,
                                    if any, Extra Effort Expenses, if any, and
                                    Post-Approval Research and Regulatory
                                    Expenses, and (iv) the amount of Net Profits
                                    to be allocated to each Party, including an
                                    explanation of any deviation from the
                                    Baseline Allocation of Net Profits made in
                                    accordance with Section 7.5.1. No such
                                    reports shall be due with respect to any
                                    Product before the First Commercial Sale of
                                    such Product in the Copromotion Territory.
                                    At the time such report is made, Wyeth

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                                   shall remit to ViroPharma the amount of Net
                                   Profits allocated to ViroPharma for such
                                   Calendar Quarter less any deductions made in
                                   accordance with Section 4.6.5.

                  7.6.4    Taxes and Withholding. All payments under this
                           Agreement will be made without any deduction or
                           withholding for or on account of any tax unless such
                           deduction or withholding is required by applicable
                           laws or regulations. If the paying Party is so
                           required to deduct or withhold such Party will (i)
                           promptly notify the other Party of such requirement,
                           (ii) pay to the relevant authorities the full amount
                           required to be deducted or withheld promptly upon the
                           earlier of determining that such deduction or
                           withholding is required or receiving notice that such
                           amount has been assessed against the other Party,
                           (iii) promptly forward to the other Party an official
                           receipt (or certified copy) or other documentation
                           reasonably acceptable to the other Party evidencing
                           such payment to such authorities.

                  7.6.5    Currency. All amounts payable and calculations
                           hereunder shall be in United States dollars. As
                           applicable, Net Sales, Net Profits and any expenses
                           incurred by either Party shall be translated into
                           United States dollars in accordance with Wyeth's
                           customary and usual translation procedures,
                           consistently applied. If, due to restrictions or
                           prohibitions imposed by national or international
                           authority, payments cannot be made as provided in
                           this Article 7, the Parties shall consult with a view
                           to finding a prompt and acceptable solution, and
                           Wyeth will deal with such monies as ViroPharma may
                           lawfully direct at no additional out-of-pocket
                           expense to Wyeth. Notwithstanding the foregoing, if
                           payments arising in connection with the sale of
                           Products in any country cannot be remitted to
                           ViroPharma for any reason within six (6) months after
                           the end of the Calendar Quarter during which they are
                           earned, then Wyeth shall be obligated to deposit the
                           royalties in a bank account in such country in the
                           name of ViroPharma.

         7.7      Maintenance of Records; Audits.

                  7.7.1    Record Keeping for the Copromotion Territory. Wyeth
                           shall keep and maintain accurate and complete records
                           in connection with the sale of Products in the
                           Copromotion Territory hereunder and each Party shall
                           keep and maintain accurate and complete records
                           showing the expenses incurred and efforts employed by
                           or on behalf of it or its Affiliates in Promoting
                           Products in the Copromotion Territory hereunder,
                           which books and records shall be in sufficient detail
                           to permit the accurate determination of Net Sales,
                           Net Profits (including, without limitation, the
                           deduction of each Party's expenses from Net Profits
                           pursuant to Section 1.70), and all other figures
                           necessary for the verification of the allocation of
                           Net Profits to be made under Section 7.5. Each Party
                           shall maintain and cause its Affiliates to maintain
                           such records for a period of at least

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                           three (3) years after the end of the calendar year in
                           which they were generated.

                  7.7.2    Record Keeping for the Wyeth Territory. Wyeth shall
                           keep and shall cause its Affiliates and sublicensees
                           to keep accurate books and accounts of record in
                           connection with the sale of Products in the Wyeth
                           Territory in sufficient detail to permit accurate
                           determination of all figures necessary for
                           verification of royalties to be paid hereunder. Wyeth
                           and its Affiliates and sublicensees shall maintain
                           such records for a period of at least three (3) years
                           after the end of the calendar year in which they were
                           generated.

                  7.7.3    Audits. Upon thirty (30) days prior written notice
                           from a Party (the "Auditing Party"), the other Party
                           (the "Audited Party") shall permit an independent
                           certified public accounting firm of nationally
                           recognized standing selected by the Auditing Party
                           and reasonably acceptable to the Audited Party, to
                           examine, at the Auditing Party's sole expense, the
                           relevant books and records of the Audited Party and
                           its Affiliates as may be reasonably necessary to
                           verify the accuracy of the reports submitted by the
                           Audited Party in accordance with Section 7.6 and the
                           calculation and allocation of Net Profits or the
                           payment of royalties hereunder, as applicable. An
                           examination by a Party under this Section 7.7.3 shall
                           occur not more than once in any calendar year and
                           shall be limited to the pertinent books and records
                           for any calendar year ending not more than thirty-six
                           (36) months before the date of the request. The
                           accounting firm shall be provided access to such
                           books and records at the Audited Party's
                           facility(ies) where such books and records are
                           normally kept and such examination shall be conducted
                           during the Audited Party's normal business hours. The
                           Audited Party may require the accounting firm to sign
                           a standard non-disclosure agreement before providing
                           the accounting firm access to the Audited Party's
                           facilities or records. Upon completion of the audit,
                           the accounting firm shall provide both Wyeth and
                           ViroPharma a written report disclosing whether the
                           reports submitted by the Audited Party are correct or
                           incorrect, whether the calculation and allocation of
                           Net Profits are correct or incorrect, whether the
                           royalties paid are correct or incorrect, and, in each
                           case, the specific details concerning any
                           discrepancies. No other information shall be provided
                           to the Auditing Party.

                  7.7.4    Underpayments/Overpayments. If such accounting firm
                           correctly concludes that additional Net Profits were
                           due to ViroPharma or that additional royalties were
                           due to ViroPharma, Wyeth shall pay to ViroPharma the
                           additional Net Profits or additional royalties, as
                           applicable, together with any interest that may be
                           due thereon as provided in Section 7.8 within thirty
                           (30) days of the date Wyeth receives such
                           accountant's written report so correctly concluding.
                           If such underpayment exceeds five percent (5%) of the
                           Net Profits that were to be distributed to

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                  ViroPharma or the royalties that were to be paid to
                  ViroPharma, as applicable, Wyeth also shall reimburse
                  ViroPharma for the out-of-pocket expenses incurred in
                  conducting the audit, except in the event that such
                  underpayment was due to any inaccurate information provided by
                  ViroPharma to Wyeth. If such accounting firm correctly
                  concludes that additional Net Profits were to be allocated to
                  Wyeth (i.e., there was an overpayment in the distribution of
                  Net Profits to ViroPharma) or that Wyeth overpaid royalties to
                  ViroPharma, ViroPharma will refund such overpayments to Wyeth,
                  together with any interest that may be due thereon as provided
                  in Section 7.8, within thirty (30) days of the date ViroPharma
                  receives such accountant's report so correctly concluding. If
                  the amount of such overpayment that is due to any inaccurate
                  information provided by ViroPharma to Wyeth exceeds five
                  percent (5%) of the Net Profits that were to be paid to
                  ViroPharma or the royalties that were to be paid to
                  ViroPharma, as applicable, ViroPharma also shall reimburse
                  AHCP for any out-of-pocket expenses incurred by Wyeth in
                  conducting the audit.

          7.7.5   Confidentiality. All financial information of a Party which is
                  subject to review under this Section 7.7 shall be deemed to be
                  Confidential Information subject to the provisions of Article
                  9, and such Confidential Information shall not be disclosed to
                  any Third Party or used for any purpose other than verifying
                  payments to be made by one Party to the other hereunder,
                  provided, however, that such Confidential Information may be
                  disclosed to Third Parties only to the extent necessary to
                  enforce a Party's rights under this Agreement.

     7.8  Interest. Any payment under this Article 7 that is more than
          forty-five (45) days past due shall thereafter be subject to interest
          at an annual percentage rate of twelve percent (12%). Likewise, any
          overpayment that is not refunded within forty-five (45) days after the
          date such overpayment was identified shall thereafter be subject to
          interest at an annual percentage rate of twelve percent (12%),
          provided, however, that if the overpayment is due to errors in reports
          provided by the overpaid Party, such interest shall accrue from the
          date the overpayment was made.

8.   INTELLECTUAL PROPERTY.

     8.1  Inventions. Subject to the provisions of Article 2, a Party shall own:
          (a) all of its Prior Inventions, (b) all of its Non-Collaboration
          Inventions, and (c) all Patent Rights claiming such Prior Inventions
          and Non-Collaboration Inventions. Also, subject to the provisions of
          Article 2, both Parties shall jointly own all Collaboration
          Inventions, Collaboration Patent Rights and Collaboration Know-How.
          All determinations of inventorship under this Agreement shall be made
          in accordance with United States patent law.

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     8.2  Patent Rights.

          8.2.1   Prosecution and Maintenance of Patent Rights.

                  (a)   ViroPharma's Prior Inventions and Non-Collaboration
                        Inventions. ViroPharma shall have the first right to
                        prepare, file, prosecute and maintain, throughout the
                        world, all Patent Rights claiming ViroPharma's Prior
                        Inventions and Non-Collaboration Inventions. With
                        respect to any ViroPharma Prior Invention or
                        Non-Collaboration Invention that is applicable in the
                        Field, ViroPharma shall give Wyeth an opportunity to
                        review and comment upon the text of the applications
                        before filing, shall consult with Wyeth with respect to
                        such application, and shall supply Wyeth with a copy of
                        the applications as filed, together with notice of its
                        filing date and serial number. ViroPharma shall keep
                        Wyeth advised of the status of the actual and
                        prospective patent filings (including, without
                        limitation, the grant of any Patent Rights that are
                        applicable in the Field), and shall provide advance
                        copies of any official correspondence related to the
                        filing, prosecution and maintenance of such patent
                        filings. If ViroPharma elects not to file a patent
                        application or to cease the prosecution and/or
                        maintenance of any Patent Right claiming a ViroPharma
                        Prior Invention or Non-Collaboration Invention that
                        relates to any Collaboration Target, any Active Compound
                        and/or any Assay and Screening Technology and that is
                        applicable in the Field, ViroPharma shall provide Wyeth
                        with written notice immediately upon the decision to not
                        file or continue the prosecution of such patent
                        application or maintenance of such patent and at least
                        sixty (60) days before ceasing prosecution and/or
                        maintenance of a particular Patent Right that is
                        applicable in the Field and, in such case, shall permit
                        Wyeth, at Wyeth's sole discretion, to file and/or
                        continue prosecution and/or maintenance of such Patent
                        Right on ViroPharma's behalf and at Wyeth's own expense.
                        If Wyeth elects to continue prosecution or maintenance,
                        ViroPharma shall execute such documents and perform such
                        acts, at Wyeth's expense, as may be reasonably necessary
                        to permit Wyeth to file, prosecute and/or maintain such
                        Patent Rights.

                  (b)   Wyeth's Prior Inventions and Non-Collaboration
                        Inventions. Wyeth, at its own expense, shall have the
                        sole right to prepare, file, prosecute and maintain,
                        throughout the world, all Patent Rights claiming any of
                        Wyeth's Prior Inventions and/or Non-Collaboration
                        Inventions in countries and regions of the world of
                        Wyeth's choice. With respect to patent applications
                        filed or to be filed in the Copromotion Territory
                        claiming any Wyeth Prior

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                        Inventionor Non-Collaboration Invention that relates to
                        any Active Compound and is applicable in the Field,
                        Wyeth shall give ViroPharma an opportunity to review and
                        comment upon the text of such applications before
                        filing, shall consult with ViroPharma with respect to
                        such applications, and shall supply ViroPharma with a
                        copy of such applications as filed, together with notice
                        of its filing date and serial number. Wyeth shall keep
                        ViroPharma advised of the status of such actual and
                        prospective patent filings (including, without
                        limitation, the grant of any Patent Rights that are
                        applicable in the Field), and shall provide advance
                        copies of any official correspondence related to the
                        filing, prosecution and maintenance of such patent
                        filings. If Wyeth elects not to file a patent
                        application or to cease the prosecution and/or
                        maintenance of any such Patent Right, Wyeth shall
                        provide ViroPharma with written notice immediately upon
                        the decision to not file or continue the prosecution of
                        such patent application or maintenance of such patent
                        and at least sixty (60) days before ceasing prosecution
                        and/or maintenance of a particular Patent Right that is
                        applicable in the Field and, in such case, shall permit
                        ViroPharma, at the ViroPharma's sole discretion, to file
                        and/or continue prosecution and/or maintenance of such
                        Patent Right on behalf of Wyeth at ViroPharma's own
                        expense. If ViroPharma elects to continue prosecution or
                        maintenance, Wyeth shall execute such documents and
                        perform such acts, at ViroPharma's expense, as may be
                        reasonably necessary to permit ViroPharma to file,
                        prosecute and/or maintain such Patent Rights.

                  (c)   Collaboration Inventions. Wyeth shall have the first
                        right to prepare, file, prosecute and maintain any
                        Patent Right claiming any Collaboration Invention
                        throughout the world. Wyeth shall give ViroPharma an
                        opportunity to review the text of the applications
                        before filing, shall consult with ViroPharma with
                        respect thereto, and shall supply ViroPharma with a copy
                        of the applications as filed, together with notice of
                        its filing date and serial number. Wyeth shall keep
                        ViroPharma advised of the status of the actual and
                        prospective patent filings (including, without
                        limitation, the grant of any Patent Rights), and shall
                        provide advance copies of any official correspondence
                        related to the filing, prosecution and maintenance of
                        such patent filings. ViroPharma shall reimburse Wyeth
                        for fifty percent (50%) of the costs incurred by Wyeth
                        in preparing, filing, prosecuting and maintaining such
                        Patent Rights, which reimbursement will be made pursuant
                        to invoices submitted by Wyeth to ViroPharma no more
                        often than once per Calendar Quarter. If either Party at
                        any time declines to share in the costs of filing,
                        prosecuting and maintaining any such Patent Right in the
                        Field, on a country by country basis, such Party shall
                        provide the

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                        other Party with thirty (30) days prior written notice
                        to such effect, in which event, such Party shall (i)
                        have no responsibility for any expenses incurred in
                        connection with such Patent Right after the end of such
                        thirty (30) day period and (ii) if the other Party
                        elects to continue prosecution or maintenance, assign to
                        the other Party all of its right, title and interest in
                        and to such Patent Right and the underlying
                        Collaboration Invention. If the other Party elects to
                        continue prosecution or maintenance, the assigning Party
                        shall execute such documents and perform such acts, at
                        the receiving Party's expense, as may be reasonably
                        necessary to effect an assignment of such Patent Rights
                        to the receiving Party on a country by country basis and
                        to allow the receiving Party to continue the prosecution
                        and maintenance of such Patent Right. Any such
                        assignment shall be completed in a timely manner to
                        allow the receiving Party to continue such prosecution
                        or maintenance. Upon the assignment of such Patent Right
                        to the other Party, such Patent Right shall cease to be
                        a Collaboration Patent Right on a country by country
                        basis for purposes of this Agreement, and, thereafter
                        shall be considered to be a Non-Collaboration Invention
                        of the Party receiving such assignment for all purposes
                        of this Agreement.

          8.2.2   Enforcement of Patent Rights.

                  (a)   Notice and Discontinuance of Infringement - General. If
                        either Wyeth or ViroPharma becomes aware of any
                        infringement, anywhere in the world, of any issued
                        patent within the Patent Rights, it will notify the
                        other Party in writing to that effect. Any such notice
                        shall include evidence to support an allegation of
                        infringement by such Third Party. The Party responsible
                        for prosecuting and maintaining such Patent Right in
                        accordance with Section 8.2.1 shall have the right, but
                        not the obligation, to take action to obtain a
                        discontinuance of such infringement or bring suit
                        against the Third Party infringer within three (3)
                        months from the date of said notice. ViroPharma shall
                        bear all the expenses of any suit brought by it claiming
                        infringement of any ViroPharma Patent Rights. Wyeth
                        shall bear all the expenses of any suit brought by it
                        claiming infringement of any Wyeth Patent Rights.
                        Subject to Section 8.2.2(c), the Parties shall share
                        equally the expenses of any suit brought by Wyeth
                        claiming infringement of any Collaboration Patent
                        Rights.

                  (b)   Wyeth Patent Rights and ViroPharma Patent Rights. With
                        respect to suits claiming infringement of either the
                        Wyeth Patent

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                        Rights or the ViroPharma Patent Rights, the Party not
                        bringing such suit (the "Non-Prosecuting Party") shall
                        have the right, before commencement of the trial, suit
                        or action brought by the other Party (the "Prosecuting
                        Party"), to join any such suit or action, and in such
                        event shall pay one-half of the costs of such suit or
                        action. In no event shall the Prosecuting Party enter
                        into any settlement, consent judgment or other voluntary
                        final disposition of such suit which would adversely
                        affect the Non-Prosecuting Party's rights under this
                        Agreement in any way without first obtaining the
                        Non-Prosecuting Party's written consent to do so, which
                        consent shall not be unreasonably withheld.
                        Additionally, if the Non-Prosecuting Party has joined in
                        the action and shared in the costs thereof as set forth
                        above, no settlement, consent judgment or other
                        voluntary final disposition of the suit may be entered
                        into without the consent of the Non-Prosecuting Party,
                        which consent shall not be unreasonably withheld. If the
                        Non-Prosecuting Party has not joined the suit or action,
                        the Non-Prosecuting Party will reasonably cooperate with
                        the Prosecuting Party in any such suit or action and
                        shall have the right to consult with the Prosecuting
                        Party and be represented by its own counsel at its own
                        expense. Any recovery or damages derived from a suit in
                        which the Non-Prosecuting Party has joined and shared
                        costs shall be used first to reimburse each of the
                        Prosecuting Party and the Non-Prosecuting Party for its
                        respective documented out-of-pocket legal expenses
                        relating to the suit, with any remaining amounts to be
                        shared equally by the Parties. Any recovery or damages
                        derived from a suit that the Non-Prosecuting Party has
                        not joined shall be retained by the Prosecuting Party.

                  (c)   Collaboration Patent Rights. With respect to suits
                        claiming infringement of the Collaboration Patent
                        Rights, Wyeth shall have the first right to bring suit
                        claiming infringement of the Collaboration Patent
                        Rights. ViroPharma shall have the right, before
                        commencement of the trial, suit or action brought by
                        Wyeth, to join any such suit or action. In no event
                        shall Wyeth enter into any settlement, consent judgment
                        or other voluntary final disposition of such suit which
                        would adversely affect ViroPharma's rights under this
                        Agreement in any way without first obtaining
                        ViroPharma's written consent to do so, which consent
                        shall not be unreasonably withheld. If Wyeth declines to
                        bring suit, ViroPharma may proceed with an infringement
                        suit. Any recovery or damages derived from such a suit
                        shall be used first to reimburse each of Wyeth and
                        ViroPharma for their respective documented out-of-pocket
                        legal expenses relating to the suit, with any remaining
                        amounts to be shared equally by the Parties. If either
                        Party desires not to proceed with or participate in a
                        suit

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                        against a Third Party for infringement of a
                        Collaboration Patent Right, such Party may, by written
                        notice to the other Party, elect not to share in the
                        expenses of such suit. In such event, the Party
                        continuing to prosecute the infringement action shall
                        have the right, but not the obligation to bring or
                        continue such suit at its own expense and shall be
                        entitled to retain any recovery or damages derived from
                        such suit, and the Party electing not to participate in
                        the suit shall reasonably cooperate with such other
                        Party in prosecuting such infringement action. The Party
                        bringing such action shall incur no liability to the
                        other Party as a consequence of such litigation or any
                        unfavorable decision resulting therefrom, including any
                        decision holding any of the Collaboration Patent Rights
                        invalid or unenforceable.

                  (d)   Continuance of Infringement of the ViroPharma Patent
                        Rights. With respect to the ViroPharma Patent Rights,
                        if, after the expiration of the three (3) month period
                        specified in Section 8.2.2(a), ViroPharma has not
                        obtained a discontinuance of infringement of its Patent
                        Rights, filed suit against any Third Party infringer of
                        its Patent Rights, or provided Wyeth with information
                        and arguments demonstrating to Wyeth's reasonable
                        satisfaction that there is insufficient basis for the
                        allegation of infringement of ViroPharma's Patent
                        Rights, then Wyeth shall have the right, but not the
                        obligation, to bring suit against such infringer under
                        the ViroPharma Patent Rights and to join ViroPharma as a
                        party plaintiff, provided that Wyeth shall bear all the
                        expenses of such suit. ViroPharma will cooperate with
                        Wyeth in any suit for infringement of ViroPharma's
                        Patent Rights brought by Wyeth against a Third Party,
                        and shall have the right to consult with Wyeth and to
                        participate in and be represented by independent counsel
                        in such litigation at its own expense. Wyeth shall incur
                        no liability to ViroPharma as a consequence of such
                        litigation or any unfavorable decision resulting
                        therefrom, including any decision holding any of the
                        ViroPharma Patent Rights invalid or unenforceable.

                  (e)   Continuance of Infringement of the Wyeth Patent Rights.
                        With respect to the Wyeth Patent Rights in the
                        Copromotion Territory which claim an Active Compound in
                        the Field, if, after the expiration of the three (3)
                        month period specified in Section 8.2.2(a), Wyeth has
                        not obtained a discontinuance of infringement of such
                        Patent Rights in the Field, filed suit against any Third
                        Party infringer of such Patent Rights, or provided
                        ViroPharma with information and arguments demonstrating
                        to ViroPharma's reasonable satisfaction that there is
                        insufficient basis for the allegation of infringement of
                        such Patent Rights in the Field, then

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                        ViroPharma shall have the right, but not the obligation,
                        to bring suit against such infringer under such of the
                        Wyeth Patent Rights and to join Wyeth as a party
                        plaintiff, provided that ViroPharma shall bear all the
                        expenses of such suit. Wyeth will cooperate with
                        ViroPharma in any suit for infringement of such of
                        Wyeth's Patent Rights brought by ViroPharma against a
                        Third Party, and shall have the right to consult with
                        ViroPharma and to participate in and be represented by
                        independent counsel in such litigation at its own
                        expense. ViroPharma shall incur no liability to Wyeth as
                        a consequence of such litigation or any unfavorable
                        decision resulting therefrom, including any decision
                        holding any of such Wyeth Patent Rights invalid or
                        unenforceable.

          8.2.3   Infringement and Third Party Licenses.

                  (a)   Infringement of Third Party Patents - Course of Action.
                        If the making, having made, importing, exporting, using,
                        distributing, marketing, promoting, offering for sale or
                        selling any Compound and/or Product in the Field, under
                        this Agreement, is alleged by a Third Party to infringe
                        a Third Party's patent, the Party becoming aware of such
                        allegation shall promptly notify the other Party.
                        Additionally, if either Party determines that, based
                        upon the review of a Third Party's patent or patent
                        application, it may be desirable to obtain a license
                        from such Third Party with respect thereto so as to
                        avoid any potential suit between either Party and such
                        Third Party, such Party shall promptly notify the other
                        Party of such determination.

                  (b)   Wyeth Option to Negotiate. Wyeth shall in the first
                        instance have the right to negotiate with said Third
                        Party for a suitable license or assignment, provided,
                        however, that Wyeth shall enter into no such agreement
                        unless it has first obtained ViroPharma's approval of
                        the terms of such agreement, including the amounts of
                        any royalties or payments, which approval shall not be
                        unreasonably withheld. If such negotiation results in a
                        consummated agreement, Wyeth shall make all payments to
                        the Third Party and such payments shall be deemed Third
                        Party License Fees for purposes of this Agreement.

                  (c)   Third Party Infringement Suit. If a Third Party sues a
                        Party (the "Sued Party") alleging that the Sued Party's,
                        the Sued Party's Affiliates' or the Sued Party's
                        sublicensees' use of any Collaboration Target for the
                        Screening of Compounds pursuant to this Agreement, or
                        the Screening, Research, Development, or
                        Commercialization of any Compound and/or Product in the
                        Field during the term of and pursuant to this Agreement
                        infringes or will

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                        infringe said Third Party's patent, then upon the Sued
                        Party's request and in connection with the Sued Party's
                        defense of any such Third Party infringement suit, the
                        other Party shall provide reasonable assistance to the
                        Sued Party for such defense. The Parties shall equally
                        share in the litigation expenses, including settlement
                        costs, royalties paid in settlement of any such suit,
                        and the payment of any damages to the Third Party, other
                        than Third Party License Fees paid pursuant to Section
                        8.2.3(e). The Party paying such expenses shall
                        periodically, but no more than once per Calendar
                        Quarter, invoice the other Party for its
                        ******************* share of expenses incurred, which
                        invoices shall be accompanied by supporting
                        documentation reasonably showing the expenses so
                        incurred. Such invoices shall be paid within thirty (30)
                        days of receipt, provided, however, that if Wyeth is the
                        Sued Party, ViroPharma has earned royalties pursuant to
                        Section 7.4 or Net Profits pursuant to Section 7.5, and
                        Wyeth has invoiced ViroPharma for expenses under this
                        Section 8.2.3(c) but ViroPharma has not yet paid them
                        Wyeth may deduct ViroPharma's ******************* share
                        of such expenses from such royalties or Net Profits due
                        to ViroPharma. The obligation to share expenses pursuant
                        to this Section 8.2.3(c) shall not apply to activities
                        conducted by either Party: (a) with respect to any
                        Collaboration Target after such Target has ceased to be
                        a Collaboration Target pursuant to Section 4.4.1, (b)
                        with respect to any Compound that has not been declared
                        a Hit in accordance with Section 4.4.3, (c) with respect
                        to any Hit, Lead Compound or Development Candidate after
                        the JSC, in accordance with Section 4.4 and 2.4, has
                        determined not to advance the development of such Hit,
                        Lead Compound, or Development Candidate, or (d) after
                        the expiration or any termination of this Agreement.

                  (d)   Other Third Party Licenses. If the Parties determine
                        that, after consultation with intellectual property
                        counsel, obtaining a license from a Third Party under
                        such Third Party's intellectual property rights is
                        necessary or useful for Screening, Research, Development
                        or Commercialization of any Compound or Product under
                        this Agreement, the JSC or the MSC shall determine which
                        Party shall have the responsibility to negotiate and
                        enter into an agreement with such Third Party for such a
                        license. The Party entering into such agreement shall
                        pay the Third Party License Fees due thereunder to such
                        Third Party, subject to reimbursement in accordance with
                        Section 8.2.3(e).

                  (e)   Third Party License Fees. ViroPharma shall be
                        responsible for ******************* of all Third Party
                        License Fees paid by either Party pursuant to this
                        Section 8.2.3 and Wyeth shall be

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                        responsible for ******************** of all Third Party
                        License Fees paid by either Party pursuant to this
                        Sections 8.2.3. Notwithstanding the foregoing, if,
                        pursuant to Section 8.2.3(d), Wyeth determines it is
                        necessary or desirable to obtain a license from a Third
                        Party to allow the Screening, Research, Development
                        and/or Commercialization of any Class A Compound or
                        Product containing a Class A Compound,
                        *************************. The Party receiving such
                        invoice shall reimburse the other Party for its share of
                        such Third Party License Fees within forty-five (45)
                        days after receiving the invoice therefor.

          8.2.4   Patent Certifications. Each Party shall immediately give
                  written notice to the other of any certification of which it
                  becomes aware filed pursuant to 21 U.S.C.(S) 355(b)(2)(A),
                  or(S) 355(j)(2)(A)(vii) (or any amendment or successor statute
                  thereto) claiming that Patent Rights covering any Product are
                  invalid or that infringement will not arise from the
                  manufacture, use or sale of such Product by a Third Party.
                  Notwithstanding any provision to the contrary, in the event
                  that the Patent Rights at issue are owned and/or Controlled by
                  ViroPharma and ViroPharma has failed to bring an infringement
                  action against such Third Party at least fourteen (14) days
                  prior to expiration of the forty five (45) day period set
                  forth in 21 U.S.C.(S)355(c)(3)(C) (or any amendment or
                  successor statute thereto), Wyeth shall have the right to
                  bring such an infringement action, in its sole discretion and
                  at its own expense, in its own name and/or in the name of
                  ViroPharma. At Wyeth's request, ViroPharma shall, at its own
                  expense, provide Wyeth reasonable assistance to conduct such
                  infringement action, including, without limitation, causing
                  the execution of such legal documents as Wyeth may deem
                  necessary for the prosecution of such action. Wyeth shall
                  incur no liability to ViroPharma as a consequence of such
                  litigation or any unfavorable decision resulting therefrom,
                  including any decision holding any of the Patent Rights
                  invalid or unenforceable. In the event that Wyeth recovers any
                  sums in such litigation by way of damages or in settlement
                  thereof, Wyeth shall have the right to retain all such sums to
                  offset its costs, losses and expenses.

          8.2.5   Patent Term Restoration. The Parties hereto shall cooperate
                  with each other in obtaining patent term restoration or its
                  equivalent in the world where applicable to Patent Rights. If
                  elections with respect to obtaining such patent term
                  restoration are to be made, the President, Wyeth-Ayerst Global
                  Pharmaceuticals, and the President, ViroPharma Incorporated,
                  or their designees, shall agree to an election and the Parties
                  shall abide by such election.

     8.3  Trademarks. Wyeth shall, in its sole discretion, select and own all
          Trademarks, Product names and Compound names to be used in connection
          with the marketing, promotion and sale of any Product hereunder.
          ViroPharma shall

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          neither use nor seek to register, anywhere in the world, any
          trademarks which are confusingly similar to any Trademark or any other
          trademarks, trade names, trade dress or logos used by or on behalf of
          Wyeth, its Affiliates or sublicensees in connection with any Product.
          Nothing in this Section 8.3 shall prevent or limit ViroPharma in any
          way from continuing to use any trademark, trade name, trade dress or
          logo adopted by ViroPharma before the date that the same or a
          confusingly similar trademark, trade name, trade dress or logo is
          adopted by Wyeth.

9.   CONFIDENTIALITY.

     9.1  Confidentiality. Except to the extent expressly authorized by this
          Agreement or otherwise agreed in writing, the Parties agree that, for
          the term of this Agreement and for five (5) years thereafter, each
          Party (the "Receiving Party"), receiving hereunder any Confidential
          Information of the other Party (the "Disclosing Party") shall keep
          such Confidential Information confidential and shall not publish or
          otherwise disclose or use such Confidential Information for any
          purpose other than as provided for in this Agreement except for
          Confidential Information that the Receiving Party can establish:

          (a)  was already known to the Receiving Party (other than under an
               obligation of confidentiality), at the time of disclosure by the
               Disclosing Party and such Receiving Party has documentary
               evidence to that effect;

          (b)  was generally available to the public or otherwise part of the
               public domain at the time of its disclosure to the Receiving
               Party;

          (c)  became generally available to the public or otherwise part of the
               public domain after its disclosure or development, as the case
               may be, and other than through any act or omission of a party in
               breach of this confidentiality obligation;

          (d)  was disclosed to that Party, other than under an obligation of
               confidentiality, by a Third Party who had no obligation to the
               Disclosing Party not to disclose such information to others;

          (e)  was independently discovered or developed by or on behalf of the
               Receiving Party without the use of the Confidential Information
               belonging to the other Party and the Receiving Party has
               documentary evidence to that effect.

     9.2  Authorized Disclosure and Use.

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          9.2.1  Disclosure. Notwithstanding the foregoing Section 9.1, each
                 Party may disclose Confidential Information belonging to the
                 other Party to the extent such disclosure is reasonably
                 necessary to:

                 (a)  file or prosecute patent applications claiming Inventions
                      included within the Collaboration Technology,

                 (b)  prosecute or defend litigation,

                 (c)  exercise rights hereunder provided such disclosure is
                      covered by terms of confidentiality similar to those set
                      forth herein, and

                 (d)  comply with applicable governmental laws and regulations.

                 In the event a Party shall deem it necessary to disclose
                 pursuant to this Section 9.2.1, Confidential Information
                 belonging to the other Party, the Disclosing Party shall to the
                 extent possible give reasonable advance notice of such
                 disclosure to the other Party and take reasonable measures to
                 ensure confidential treatment of such information.

          9.2.2  Use. Notwithstanding the foregoing Section 9.1, each Party
                 shall have the right to use the other Party's Confidential
                 Information in carrying out its respective responsibilities
                 under this Agreement in both the conduct of the Research
                 Program and the Development and Commercialization of Lead
                 Compounds and Products. Similarly, subject to the license
                 granted in Article 2 and the terms of this Article 9, each
                 Party shall have the right to use the Joint Confidential
                 Information for any purpose under this Agreement.

     9.3  SEC Filings. Either Party may disclose the terms of this Agreement to
          the extent required, in the reasonable opinion of such Party's legal
          counsel, to comply with applicable laws, including without limitation
          the rules and regulations promulgated by the United States Securities
          and Exchange Commission (the "SEC"). Notwithstanding the foregoing,
          before disclosing this Agreement or any of the terms hereof pursuant
          to this Section 9.3, the Parties will consult with one another on the
          terms of this Agreement to be redacted in making any such disclosure.
          If a Party discloses this Agreement or any of the terms hereof in
          accordance with this Section 9.3, such Party agrees, at its own
          expense, to seek confidential treatment of portions of this Agreement
          or such terms, as may be reasonably requested by the other Party.

     9.4  Publications. During the term of the Research Program, each Party will
          submit to the other Party for review and approval all proposed
          academic, scientific and medical publications and public presentations
          relating to the Research Program, Lead Compounds, Development
          Candidates, Products and/or Collaboration Technology for review in
          connection with preservation of exclusive Patent Rights

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          and/or to determine whether Confidential Information should be
          modified or deleted. Written copies of such proposed publications and
          presentations shall be submitted to the nonpublishing Party no later
          than sixty (60) days before submission for publication or presentation
          and the non-publishing party shall provide its comments with respect
          to such publications and presentations within fifteen (15) business
          days of its receipt of such written copy. The review period may be
          extended for an additional thirty (30) days in the event the
          nonpublishing Party can demonstrate a reasonable need for such
          extension including, but not limited to, the preparation and filing of
          patent applications. By mutual agreement, this period may be further
          extended. ViroPharma and Wyeth will each comply with standard academic
          practice regarding authorship of scientific publications and
          recognition of contribution of other parties in any publications
          relating to Research Program, Lead Compounds, Development Candidates,
          Products and/or Collaboration Technology.

     9.5  Public Announcements.

          9.5.1  Coordination. The Parties agree on the importance of
                 coordinating their public announcements respecting this
                 Agreement and the subject matter thereof (other than academic,
                 scientific or medical publications that are subject to the
                 publication provision set forth above). ViroPharma and Wyeth
                 will, from time to time, and at the request of the other Party
                 discuss and agree on the general information content relating
                 to this Agreement, the Research Program, Lead Compounds,
                 Development Candidates, Products and/or Collaboration
                 Technology which may be publicly disclosed.

          9.5.2  Announcements. Except as may be expressly permitted under
                 Sections 9.3 and 9.4, neither Party will make any public
                 announcement regarding this Agreement, the Research Program,
                 Lead Compounds, Development Candidates, Products and/or
                 Collaboration Technology without the prior written approval of
                 the other Party.

10.  REPRESENTATIONS AND WARRANTIES.

     10.1 Representations, Warranties of Each Party. As of the Effective Date,
          each of ViroPharma and Wyeth hereby represents, warrants, and
          covenants to the other Party hereto as follows:

          (a)    it is a corporation or entity duly organized and validly
                 existing under the laws of the state or other jurisdiction of
                 its incorporation or formation;

          (b)    the execution, delivery and performance of this Agreement by
                 such Party has been duly authorized by all requisite corporate
                 action and does not require any shareholder action or approval;

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          (c)    it has the power and authority to execute and deliver this
                 Agreement and to perform its obligations hereunder;

          (d)    the execution, delivery and performance by such Party of this
                 Agreement and its compliance with the terms and provisions
                 hereof does not and will not conflict with or result in a
                 breach of any of the terms and provisions of or constitute a
                 default under (i) a loan agreement, guaranty, financing
                 agreement, agreement affecting a product or other agreement or
                 instrument binding or affecting it or its property; (ii) the
                 provisions of its charter or operative documents or bylaws; or
                 (iii) any order, writ, injunction or decree of any court or
                 governmental authority entered against it or by which any of
                 its property is bound;

          (e)    it shall at all times comply with all applicable material laws
                 and regulations relating to its activities under this
                 Agreement;

          (f)    as of the Effective Date, its Patent Rights and Know-How are
                 existing and, to the best of its knowledge, are not invalid or
                 unenforceable, in whole or in part;

          (g)    it has the full right, power and authority to grant all of the
                 right, title and interest in the licenses granted to the other
                 Party under this Agreement;

     10.2 Additional Representations and Warranties of ViroPharma. In addition
          to the representations and warranties made by ViroPharma elsewhere in
          this Agreement, ViroPharma, subject to Section 10.6, hereby
          represents, warrants, and covenants to Wyeth that, as of the Effective
          Date:

          (a)    except as disclosed in Exhibit 10.2(a), as of the Effective
                 Date, no Third Party has any right, title or interest in or to:

                 (i)   any Collaboration Target listed in Exhibit 1.23,

                 (ii)  any Class A Product, or

                 (iii) any of the ViroPharma Patent Rights, ViroPharma Know-How,
                       or any of ViroPharma's interest in the Collaboration
                       Patent Rights to the extent that any of the foregoing in
                       this Section 10.2(a)(iii) cover any Collaboration Target
                       listed in Exhibit 1.23, or any Class A Product,

                 with respect to which Wyeth has been granted or is to be
                 granted a license hereunder;

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          (b)    except as disclosed in Exhibit 10.2(b), it is the sole and
                 exclusive owner of the ViroPharma Patent Rights listed on
                 Exhibit 1.114 and the ViroPharma Know-How existing as of the
                 Effective Date, all of which are free and clear of any liens,
                 charges and encumbrances, and, with respect to such Patent
                 Rights and Know-How, ViroPharma has the right to grant to Wyeth
                 those licenses granted in Section 2.1 hereof;

          (c)    except as set forth in Exhibit 10.2(c) attached hereto, no
                 ViroPharma Prior Invention and no ViroPharma Patent Right and
                 no portion of the ViroPharma Know-How existing as of the
                 Effective Date and relating to either any Class A Compound or
                 to any Collaboration Target listed on Exhibit 1.23 is subject
                 to any funding agreement with any government or government
                 agency;

          (d)    to the best of its knowledge, as of November 1, 1999, the
                 practice of the ViroPharma Patent Rights listed on Exhibit
                 1.114, the use of the ViroPharma Know-How, the use of the
                 Collaboration Targets listed in Exhibit 1.23, and the
                 manufacture, use or sale of any ViroPharma Compound each, as of
                 the Effective Date, do not infringe on any issued patents owned
                 or possessed by any Third Party;

          (e)    to the best of its knowledge, as of the Effective Date, there
                 are no Third Party pending patent applications (other than
                 those which have been disclosed, in writing, by ViroPharma to
                 Wyeth prior to the signing of this Agreement) which, if issued,
                 would cover the development, manufacture or use of any
                 Collaboration Target or the development, manufacture, use or
                 sale of any Class A Compound arising from the ViroPharma
                 Chemical Library or any Product containing any Class A Compound
                 arising from the ViroPharma Chemical Library;

          (f)    as of the Effective Date, there are no claims, judgments or
                 settlements against or owed by ViroPharma or, to the best of
                 its knowledge, pending or threatened claims or litigation in
                 either case relating to the ViroPharma Patent Rights listed in
                 Exhibit 1.114, the ViroPharma Know-How, any Collaboration
                 Target, any ViroPharma Class A Compound or any ViroPharma Class
                 B Compound that ViroPharma, as of the Effective Date, plans to
                 Screen during the Screening Phase; and

          (g)    during the Term of this Agreement it will use diligent efforts
                 not to diminish the rights under the ViroPharma Patent Rights
                 or the ViroPharma Know-How granted to Wyeth hereunder,
                 including without limitation, by not committing or permitting
                 any actions or omissions which would cause the breach of any
                 agreements between itself and Third Parties which provide for
                 intellectual property rights applicable to the development,
                 manufacture or use of any Target or the development,
                 manufacture, use or sale of any Active Compound arising from
                 the ViroPharma Chemical

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                 Library and/or Product containing any Active Compound arising
                 from the ViroPharma Chemical Library, that it will provide
                 Wyeth promptly with notice of any such alleged breach, and that
                 as of the Effective Date, it is in compliance in all material
                 respects with any agreements with Third Parties relating to the
                 ViroPharma Patent Rights, the ViroPharma Know How, the Targets
                 and/or the Active Compounds arising from the ViroPharma
                 Chemical Library.

     10.3 Additional Representations and Warranties of Wyeth. In addition to the
          representations and warranties made by Wyeth elsewhere in this
          Agreement, Wyeth, subject to Section 10.6, hereby represents,
          warrants, and covenants to ViroPharma that, as of the Effective Date:

          (a)    except as disclosed in Exhibit 10.3(a), it is the sole and
                 exclusive owner of the Wyeth Patent Rights listed on Exhibit
                 1.7 and the Wyeth Know-How existing as of the Effective Date,
                 all of which are free and clear of any liens, charges and
                 encumbrances, and, with respect to such Patent Rights and
                 Know-How Wyeth has the right to grant to ViroPharma those
                 licenses granted in Section 2.2 hereof;

          (b)    to the best of its knowledge, as of the Effective Date, the
                 practice of the Wyeth Patent Rights listed on Exhibit 1.7, the
                 use of the Wyeth Know-How, and the manufacture, use or sale of
                 any Wyeth Compound each, as of the Effective Date, do not
                 infringe on any issued patents owned or possessed by any Third
                 Party;

          (c)    as of the Effective Date, there are no claims, judgments or
                 settlements against or owed by Wyeth or, to the best of its
                 knowledge, pending or threatened claims or litigation in either
                 case relating to the Wyeth Patent Rights listed in Exhibit 1.7,
                 the Wyeth Know-How, or any Wyeth Compound that Wyeth, as of the
                 Effective Date, plans to Screen during the Screening Phase;

          (d)    all units of Product supplied in the United States by Wyeth
                 pursuant to Section 5.1 will, as of the date of shipment or
                 delivery of such Product to a common carrier, not be
                 adulterated or misbranded within the meaning of the FD&C Act,
                 and not be an article which may not, under the provisions of
                 Sections 404, 505 or 512 of the FD&C Act, be introduced into
                 interstate commerce;

          (e)    all units of Product and containers for such Product supplied
                 by Wyeth pursuant to Section 5.1 for sale in the Copromotion
                 Territory shall be manufactured, processed, prepared, packed,
                 and, while in Wyeth's possession, held in accordance with all
                 applicable federal, state, and local laws and regulations,
                 including, without limitation, all current Good

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                 Manufacturing Practices and with all applicable Regulatory
                 Approvals in the Copromotion Territory; and

          (f)    during the Term of this Agreement it will use diligent efforts
                 not to diminish the rights under the Wyeth Patent Rights or the
                 Wyeth Know-How granted to ViroPharma hereunder, including
                 without limitation, by not committing or permitting any actions
                 or omissions which would cause the breach of any agreements
                 between itself and Third Parties which provide for intellectual
                 property rights applicable to the development, manufacture, use
                 or sale of any Active Compound arising from the Wyeth Chemical
                 Library and/or Product containing any Active Compound arising
                 from the Wyeth Chemical Library, that it will provide
                 ViroPharma promptly with notice of any such alleged breach, and
                 that as of the Effective Date, it is in compliance in all
                 material respects with any agreements with Third Parties
                 relating to the Wyeth Patent Rights, the Wyeth Know How and/or
                 the Active Compounds arising from the Wyeth Chemical Library.

     10.4 Representation by Legal Counsel. Each Party hereto represents that it
          has been represented by legal counsel in connection with this
          Agreement and acknowledges that it has participated in the drafting
          hereof. In interpreting and applying the terms and provisions of this
          Agreement, the Parties agree that no presumption shall exist or be
          implied against the Party which drafted such terms and provisions.

     10.5 No Inconsistent Agreements. Neither Party has in effect and after the
          Effective Date neither Party shall enter into any oral or written
          agreement or arrangement that would be inconsistent with its
          obligations under this Agreement.

     10.6 Disclaimer. THE FOREGOING WARRANTIES OF EACH PARTY ARE IN LIEU OF ANY
          OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION,
          ANY IMPLIED WARRANTIES OF NONINFRINGEMENT, ANY IMPLIED WARRANTIES OF
          MERCHANTABILITY OR ANY IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR
          PURPOSE ALL OF WHICH ARE HEREBY SPECIFICALLY EXCLUDED AND DISCLAIMED.

11.  GOVERNMENT APPROVALS; TERM AND TERMINATION.

     11.1 Government Approvals.

          11.1.1 ViroPharma's and Wyeth's Obligations. Each of ViroPharma and
                 Wyeth shall use its good faith efforts to eliminate any concern
                 on the part of any court or government authority regarding the
                 legality of the proposed transaction, including, if required by
                 federal or state antitrust

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                 authorities, promptly taking all steps to secure government
                 antitrust clearance, including, without limitation, cooperating
                 in good faith with any government investigation including the
                 prompt production of documents and information demanded by a
                 second request for documents and of witnesses if requested.

          11.1.2 Cooperation. ViroPharma and Wyeth will cooperate and use
                 respectively all reasonable efforts to make all other
                 registrations, filings and applications, to give all notices
                 and to obtain as soon as practicable all governmental or other
                 consents, transfers, approvals, orders, qualifications
                 authorizations, permits and waivers, if any, and to do all
                 other things necessary or desirable for the consummation of the
                 transactions as contemplated hereby. Neither Party shall be
                 required, however, to divest or out-license products or assets
                 or materially change its business if doing so is a condition of
                 obtaining approval under the HSR Act or other governmental
                 approvals of the transactions contemplated by this Agreement.

     11.2 Term. The term of this Agreement will commence on the Effective Date
          and extend, unless this Agreement is terminated earlier in accordance
          with this Section 11, on a Product by Product and country by country
          basis (a) in the Wyeth Territory until such time as the obligation to
          pay royalties with respect to the sale of such Product in such country
          expires in accordance with Section 7.4.3 and (b) in the Copromotion
          Territory, until the later of (i) such time as the Parties are no
          longer copromoting such Product in such country or (ii) if the Parties
          discontinue the copromotion of Products pursuant to Section 11.6, such
          time as the obligation to pay royalties with respect to the sale of
          such Product in such country expires in accordance with Section 7.4.3.

     11.3 Expiration. If at any time after the expiration of the Screening Phase
          Tail, the Parties have determined, in accordance with Section 4.3.3,
          not to advance any Compound from a Tail Compound Series as a Hit or
          Lead Compound and there is otherwise no Active Compound hereunder,
          this Agreement shall expire effective as of the later of (a) the date
          the Parties have determined, in accordance with Section 4.3.3, not to
          advance any Compound from a Tail Compound Series as a Hit or a Lead
          Compound and (b) the date on which all Active Compounds have ceased to
          be Active Compounds hereunder.

     11.4 Termination for Cause.

          11.4.1 Termination for Cause. This Agreement may be terminated
                 effective immediately by written notice by either Party at any
                 time during the Term of this Agreement for material breach by
                 the other Party, which breach remains uncured for ninety (90)
                 days in the case of nonpayment of any amount due (unless there
                 exists a bona fide dispute as to whether such payment is owing,
                 in which case the ninety (90) day period shall be tolled

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                 pending resolution of such dispute) and one hundred eighty
                 (180) days for all other breaches, each measured from the date
                 written notice of such breach is given to the breaching Party,
                 provided, however, that if such breach is not susceptible of
                 cure within the stated period and the breaching Party uses
                 diligent good faith efforts to cure such breach, the stated
                 period will be extended by an additional ninety (90) days.

          11.4.2 Effect of Termination for Cause on License. If a Party
                 terminates this Agreement pursuant to this Section 11.4 (the
                 "Terminating Party"):

                 (a)   all licenses granted by the Terminating Party to the
                       other Party hereunder will automatically terminate;

                 (b)   all licenses granted by the other Party to the
                       Terminating Party will become fully paid up, irrevocable,
                       perpetual, royalty-free licenses;

                 (c)   the other Party will assign the Terminating Party all
                       right, title and interest in and to: (i) all regulatory
                       filings and Regulatory Approvals pertaining to any
                       Product which regulatory filings and Regulatory
                       Approvals, if any, are owned or otherwise controlled by
                       the other Party, (ii) all of the other Party's interest
                       in the Collaboration Patent Rights and the Collaboration
                       Know-How, (iii) all of the other Party's interest in any
                       Trademark, including, without limitation, the good will
                       symbolized by such Trademark used for Products, and (iv)
                       all of the other Party's interest in any copyrights
                       necessary or useful for Commercializing Products;

                 (d)   the other Party will have no right to receive royalties,
                       a share of Net Profits or any other payments which may
                       result from the sale of any Product, the occurrence of
                       any event or the conduct of any activity after the
                       effective date of such termination, provided, however,
                       that the other Party shall remain entitled to receive any
                       payments that accrued before the effective date of such
                       termination.

     11.5 Termination for Convenience.

          11.5.1 Right to Terminate. After December 9, 2003, either Party may
                 terminate this Agreement upon one hundred eighty (180) days
                 prior written notice to the other Party (a "Termination for
                 Convenience").

          11.5.2 Effect of Termination for Convenience. Upon a Termination for
                 Convenience the non-terminating Party shall have a
                 royalty-bearing, perpetual, irrevocable, worldwide, exclusive
                 license under the other Party's Technology and the other
                 Party's interest in any Collaboration Technology to develop,
                 make, have made, use, import, offer for sale and sell Products
                 in the Field in the world. For the sake of clarity, in such

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                 event, the non-terminating Party shall have no rights with
                 respect to any Compound of the terminating Party, which
                 Compound, before the effective date of such termination, was
                 not yet designated as a Lead Compound or a Development
                 Candidate in accordance with Section 4.4. Additionally, in the
                 event of a Termination for Convenience, the terminating Party
                 shall assign to the non-terminating Party all right, title and
                 interest in and to any regulatory filings and Regulatory
                 Approvals pertaining directly to the Products. If a Termination
                 for Convenience occurs before the enrollment of the first
                 patient in a Phase III Clinical Trial in any country of the
                 world, the non-terminating Party, on a Product by Product
                 basis, would pay to the terminating Party a royalty of
                 ************** of the Net Sales obtained from the sale of such
                 Product in the world by the non-terminating Party, its
                 Affiliates or sublicensees. If a Termination for Convenience
                 occurs after the completion of the first Phase III Clinical
                 Trial in any country of the world, the non-terminating Party,
                 on a Product by Product basis, would pay to the terminating
                 Party a royalty of ********************* of the Net Sales
                 obtained from the sale of such Product in the world by the
                 non-terminating Party, its Affiliates or sublicensees. Any
                 royalty that becomes payable under this Section 11.5.2 will be
                 payable on a country by country basis until the later of (i)
                 the last to expire, in such country, of the Patent Rights
                 included within the Collaboration Technology containing a Valid
                 Claim which would be infringed by the manufacture, use, import,
                 offer for sale, or sale of such Product in such country or (ii)
                 ten (10) years from the First Commercial Sale of such Product
                 in such country. The non-terminating Party shall provide
                 reports and pay such royalties to the terminating Party in the
                 manner set forth in Section 7.6.2.

     11.6 Termination of ViroPharma's Right to Promote Products.

          11.6.1 Failure to Provide Assigned Sales Force Effort. If during any
                 ******************* ViroPharma fails ****************, such
                 failure shall not be considered a material breach for purposes
                 of Section 11.4, but, Wyeth, upon sixty (60) days prior written
                 notice to ViroPharma, given within sixty (60) days after Wyeth,
                 pursuant to Section 7.6.3, distributes to ViroPharma its share
                 of Net Profits for the last Calendar Quarter of the third such
                 calendar year, may terminate ViroPharma's right to Promote
                 Products in the Copromotion Territory hereunder. Upon the
                 effective date of any such termination, Wyeth shall assume all
                 of ViroPharma's obligations with respect to the Promotion of
                 the Product in the Copromotion Territory and thereafter, shall
                 have the right to sublicense Third Parties the rights granted
                 to it by ViroPharma in the Copromotion Territory hereunder.
                 Additionally, if Wyeth, pursuant to this Section 11.6.1,
                 terminates ViroPharma's right to Promote Products in the
                 Copromotion Territory hereunder, ViroPharma shall no longer be
                 entitled to receive any share of Net Profits obtained from the
                 sale of Products in

June 26, 2003         Restated & Amended Collaboration Agreement         Page 79

<PAGE>

                 the Copromotion Territory after the effective date of such
                 termination, provided, however, that, with respect to the sale
                 of Products in the Copromotion Territory by Wyeth, its
                 Affiliates or sublicensees after the effective date of such
                 termination, Wyeth shall pay to ViroPharma royalties, on a
                 Product by Product basis, which royalties will be the sum of X,
                 Y and Z, where

                       X = either (a) for ***************************** of the
                           portion of the aggregate Net Sales obtained by Wyeth,
                           its Affiliates and sublicensees from the sale of such
                           Product in the Copromotion Territory, which Net
                           Sales, during the calendar year in question, are less
                           than or equal to *******************, or (b) for
                           ******************** of the portion of the aggregate
                           Net Sales obtained by Wyeth, its Affiliates and
                           sublicensees from the sale of such Product in the
                           Copromotion Territory, which Net Sales, during the
                           calendar year in question, are less than or equal to
                           ******************************************,

                       Y = either (a) for **************************** of the
                           portion of the aggregate Net Sales obtained by Wyeth,
                           its Affiliates and sublicensees from the sale of such
                           Product in the Copromotion Territory, which Net
                           Sales, during the calendar year in question, are
                           greater than ******************* and less than or
                           equal to *******************, or (b) for
                           ********************* of the portion of the aggregate
                           Net Sales obtained by Wyeth, its Affiliates and
                           sublicensees from the sale of such Product in the
                           Copromotion Territory, which Net Sales, during the
                           calendar year in question, are greater than
                           ******************* and less than or equal to
                           ***************, and

                       Z = either (a) for ************************* of the
                           portion of the aggregate Net Sales obtained by Wyeth,
                           its Affiliates and sublicensees from the sale of such
                           Product in the Copromotion Territory, which Net
                           Sales, during the calendar year in question, are
                           greater than **********************, or (b) for
                           **************** of the portion of the aggregate Net
                           Sales obtained by Wyeth, its Affiliates and
                           sublicensees from the sale of such Product in the
                           Copromotion Territory, which Net Sales, during the
                           calendar year in question, are greater than
                           ***********************************************.

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<PAGE>

            11.6.2 Payment and Term of Royalty. If ViroPharma's right to Promote
                   Products in the Copromotion Territory is terminated pursuant
                   to this Section 11.6, the royalties payable pursuant to this
                   Section 11.6, and as adjusted pursuant to Section 7.4.2, will
                   be payable as set forth in Section 7.4.3.

            11.6.3 Effect on Other Rights and Obligations. Except as expressly
                   provided in this Section 11.6, any termination of
                   ViroPharma's right to Promote Products in the Copromotion
                   Territory pursuant to this Section 11.6 shall have no effect
                   on any of the other rights and obligations of the Parties
                   under this Agreement, including, without limitation, the
                   rights or obligations of the Parties in conducting the
                   Research Program or the rights or obligations of the Parties
                   in the Wyeth Territory.

     11.7   Blocking Patents. If during the term of the Research Program:

            (a)    a Third Party is granted a Patent relating to a Collaboration
                   Target in the Copromotion Territory;

            (b)    either Party determines, based on the advice of patent
                   counsel, that such Patent may be infringed by the activities
                   of either Party under the Research Program with respect to
                   one or more Collaboration Targets; and

            (c)    the Parties, within ninety (90) days of making the
                   determination in Section 11.7(b) above, determine that no
                   license is available on commercially reasonable terms after
                   having attempted in good faith to obtain such a license from
                   such Third Party;

            Wyeth shall have the right, exercisable within sixty (60) days after
            the determination in Section 11.7(c) is made, upon thirty (30) days
            prior written notice to ViroPharma to terminate that portion of the
            Research Program under this Agreement covering the Collaboration
            Targets identified in Section 11.7(b). Upon such termination,
            subject to Section 11.8 hereof, with respect to such Collaboration
            Targets neither Party shall have any further rights or obligations
            under this Agreement, each Party shall retain all rights to its
            respective Know-How, Prior Inventions and Non-Collaboration
            Inventions covering only such Collaboration Targets and each Party
            shall be free to practice any Collaboration Invention and use any
            Joint-Know-How covering only such Collaboration Targets created by
            the Parties prior to such termination.

     11.8   Survival of Certain Obligations. Expiration or termination of the
            Agreement shall not relieve the Parties of any obligation accruing
            before such expiration or termination, and the provisions of
            Articles 9 and 12 and Sections 2.6, 4.3.3, 4.6.5, 4.6.6, 6.1.7(b),
            6.1.8(f-g), 7.4.3, 7.7, 7.8, 8.1, 8.3, 10.3(d-e), 11.4.2, 11.5.2,
            11.8, 13.4, 13.8, 13.9 and 13.11 shall survive the expiration of the
            Agreement. Any expiration or early termination of this Agreement
            shall be without prejudice to the rights of either Party against the
            other accrued or accruing under this Agreement

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June 26, 2003       Restated & Amended Collaboration Agreement           Page 81

<PAGE>

            before termination, including, without limitation, the obligations
            to pay royalties and distribute Net Profits for Product(s) sold
            before such termination.

     11.9   Provision for Insolvency.

            11.9.1 Termination. This Agreement may be terminated by written
                   notice by either Party at any time during the Term of this
                   Agreement upon the declaration by a court of competent
                   jurisdiction that the other Party is bankrupt and, pursuant
                   to the U.S. Bankruptcy Code such other Party's assets are to
                   be liquidated, the filing or institution of bankruptcy,
                   liquidation or receivership proceedings (other than
                   reorganization proceedings under Chapter 11 of the U.S.
                   Bankruptcy Code), or upon an assignment of a substantial
                   portion of the assets for the benefit of creditors by the
                   other Party, or in the event a receiver or custodian is
                   appointed for such Party's business, or if a substantial
                   portion of such Party's business is subject to attachment or
                   similar process; provided, however, that in the case of any
                   involuntary bankruptcy proceeding such right to terminate
                   shall only become effective if the proceeding is not
                   dismissed within sixty (60) days after the filing thereof. To
                   the extent permitted by applicable law, the effect of a
                   termination under this section 11.9.1 shall be as described
                   in Section 11.5.2, i.e., as if the Insolvent Party elected to
                   Terminate for Convenience.

            11.9.2 Effect on Licenses. All rights and licenses granted under or
                   pursuant to this Agreement by one Party to the other Party
                   are, for all purposes of Section 365(n) of Title 11 of the
                   United States Code ("Title 11"), licenses of rights to
                   "intellectual property" as defined in Title 11. Each Party
                   agrees that the other Party, as licensee of such rights under
                   this Agreement shall retain and may fully exercise all of its
                   rights and elections under Title 11. Each Party agrees during
                   the Term of this Agreement to create and maintain current
                   copies or, if not amenable to copying, detailed descriptions
                   or other appropriate embodiments, to the extent feasible, of
                   all such intellectual property. If a case is commenced by or
                   against a Party under Title 11 (the "Title 11 Party"), such
                   Party (in any capacity, including debtor-in-possession) and
                   its successors and assigns (including, without limitation, a
                   Title 11 Trustee) shall,

                   (a)  as the other Party may elect in a written request,
                        immediately upon such request:

                        (i)   perform all of the obligations provided in this
                              Agreement to be performed by the Title 11 Party
                              including, where applicable and without
                              limitation, providing to the other Party portions
                              of such intellectual property (including
                              embodiments thereof) held by the Title 11 Party
                              and such successors and assigns or otherwise
                              available to them; or

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<PAGE>

                        (ii)  provide to the other Party all such intellectual
                              property (including all embodiments thereof) held
                              by the Title 11 Party and such successors and
                              assigns or otherwise available to them; and

                   (b)  not interfere with the rights of the other Party under
                        this Agreement, or any agreement supplemental hereto, to
                        such intellectual property (including such embodiments),
                        including any right to obtain such intellectual property
                        (or such embodiments) from another entity.

            11.9.3 Rights to Intellectual Property. If a Title 11 case is
                   commenced by or against the Title 11 Party, and this
                   Agreement is rejected as provided in Title 11, and the other
                   Party elects to retain its rights hereunder as provided in
                   Title 11, then the Title 11 Party (in any capacity, including
                   debtor-in-possession) and its successors and assigns
                   (including, without limitation, a Title 11 Trustee) shall
                   provide to the other Party all such intellectual property
                   (including all embodiments thereof) held by the Title 11
                   Party and such successors and assigns, or otherwise available
                   to them, immediately upon the other Party's written request.
                   Whenever the Title 11 Party or any of its successors or
                   assigns provides to the other Party any of the intellectual
                   property licensed hereunder (or any embodiment thereof)
                   pursuant to this Section 11.9, the other Party shall have the
                   right to perform the obligations of the Title 11 Party
                   hereunder with respect to such intellectual property, but
                   neither such provision nor such performance by the other
                   Party shall release the Title 11 Party from any such
                   obligation or liability for failing to perform it.

            11.9.4 Additional Rights. All rights, powers and remedies of a Party
                   provided herein are in addition to and not in substitution
                   for any and all other rights, powers and remedies now or
                   hereafter existing at law or in equity (including, without
                   limitation, Title 11) in the event of the commencement of a
                   Title 11 case by or against the Title 11 Party. A non-Title
                   11 Party, in addition to the rights, power and remedies
                   expressly provided herein, shall be entitled to exercise all
                   other such rights and powers and resort to all other such
                   remedies as may now or hereafter exist at law or in equity
                   (including, without limitation, Title 11) in such event. The
                   Parties agree that they intend the foregoing rights to extend
                   to the maximum extent permitted by law, including, without
                   limitation, for purposes of Title 11:

                   (a)  the right of access to any intellectual property
                        (including all embodiments thereof) of the Title 11
                        Party, or any Third Party with whom the Title 11 Party
                        contracts to perform an obligation of the Title 11 Party
                        under this Agreement, and, in the case of the Third
                        Party, which is necessary for the Development,
                        registration,

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June 26, 2003       Restated & Amended Collaboration Agreement          Page 83

<PAGE>

                        manufacture and Commercialization of licensed Compounds
                        and/or licensed Products; and

                   (b)  the right to contract directly with any Third Party
                        described in 11.9.4(a) to complete the contracted work.

12.  INDEMNIFICATION AND INSURANCE.

     12.1   Indemnification by Wyeth. Wyeth will indemnify, defend and hold
            harmless ViroPharma, its Affiliates, and each of its and their
            respective employees, officers, directors and agents (each, a
            "ViroPharma Indemnified Party") from and against any and all
            liability, loss, damage, expense (including reasonable attorneys'
            fees and expenses) and cost (collectively, a "Liability") that the
            ViroPharma Indemnified Party may be required to pay to one or more
            Third Parties resulting from or arising out of:

            (a)    any claims of any nature, other than claims by Third Parties
                   relating to patent infringement, arising out of the conduct
                   of the Research Program by, on behalf of, or under the
                   authority of Wyeth (other than by ViroPharma);

            (b)    any Wyeth representation or warranty set forth herein being
                   untrue in any material respect when made;

            (c)    the Promotion of any Product by Wyeth in the world;

            (d)    any claim of any nature, including any products liability
                   claim, directly arising from the failure of a Product or its
                   container to have been manufactured, processed, prepared,
                   packed, or held in accordance with federal, state, and local
                   laws and regulations, Regulatory Approvals, or Wyeth's
                   representations or warranties hereunder; and/or

            (e)    any claims of any nature to the effect that any Trademark
                   selected by Wyeth in accordance with Section 8.3 and used by
                   the Parties, their Affiliates, or their sublicensees in
                   conjunction with the Promotion, marketing or sale of any
                   Product pursuant to this Agreement infringes the rights of
                   any Third Party;

            except in each case, to the extent caused by the negligence or
            willful misconduct of ViroPharma or any ViroPharma Indemnified
            Party. Notwithstanding the foregoing, Wyeth shall have no obligation
            to defend, indemnify or hold harmless any ViroPharma Indemnified
            Party from and

--------------------------------------------------------------------------------
June 26, 2003       Restated & Amended Collaboration Agreement           Page 84

<PAGE>

            against any Liability arising out of or resulting from the
            infringement of a Third Party patent.

     12.2   Indemnification by ViroPharma. ViroPharma will indemnify, defend and
            hold harmless Wyeth, its Affiliates, sublicensees, distributors and
            each of its and their respective employees, officers, directors and
            agents (each, an "Wyeth Indemnified Party") from and against any and
            all Liabilities that the Wyeth Indemnified Party may be required to
            pay to one or more Third Parties arising out of:

            (a)    any claims of any nature, other than claims by Third Parties
                   relating to patent infringement, arising out of the conduct
                   of the Research Program by, on behalf of, or under the
                   authority of ViroPharma (other than by Wyeth);

            (b)    any ViroPharma representation or warranty set forth herein
                   being untrue in any material respect when made; and/or

            (c)    the Promotion of any Product by ViroPharma in the Copromotion
                   Territory;

            except in each case, to the extent caused by the negligence or
            willful misconduct of Wyeth or any Wyeth Indemnified Party.
            Notwithstanding the foregoing, ViroPharma shall have no obligation
            to defend, indemnify or hold harmless any Wyeth Indemnified Party
            from and against any Liability arising out of or resulting from the
            infringement of a Third Party patent.

     12.3   Procedure. Each Party will notify the other in the event it becomes
            aware of a claim for which indemnification may be sought hereunder.
            In case any proceeding (including any governmental investigation)
            shall be instituted involving any Party in respect of which
            indemnity may be sought pursuant to this Article 12, such Party (the
            "Indemnified Party") shall promptly notify the other Party (the
            "Indemnifying Party") in writing and the Indemnifying Party and
            Indemnified Party shall meet to discuss how to respond to any claims
            that are the subject matter of such proceeding. The Indemnifying
            Party, upon request of the Indemnified Party, shall retain counsel
            reasonably satisfactory to the Indemnified Party to represent the
            Indemnified Party and shall pay the fees and expenses of such
            counsel related to such proceeding. In any such proceeding, the
            Indemnified Party shall have the right to retain its own counsel,
            but the fees and expenses of such counsel shall be at the expense of
            the Indemnified Party unless (i) the Indemnifying Party and the
            Indemnified Party shall have mutually agreed to the retention of
            such counsel or (ii) the named parties to any such proceeding
            (including any impleaded parties) include both the Indemnifying
            Party and the Indemnified Party and

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            representation of both parties by the same counsel would be
            inappropriate due to actual or potential differing interests between
            them. All such fees and expenses shall be reimbursed as they are
            incurred. The Indemnifying Party shall not be liable for any
            settlement of any proceeding effected without its written consent,
            but if settled with such consent or if there be a final judgment for
            the plaintiff, the Indemnifying Party agrees to indemnify the
            Indemnified Party from and against any loss or liability by reason
            of such settlement or judgment. The Indemnifying Party shall not,
            without the written consent of the Indemnified Party, effect any
            settlement of any pending or threatened proceeding in respect of
            which the Indemnified Party is, or arising out of the same set of
            facts could have been, a party and indemnity could have been sought
            hereunder by the Indemnified Party, unless such settlement includes
            an unconditional release of the Indemnified Party from all liability
            on claims that are the subject matter of such proceeding.

     12.4   Insurance. Each Party further agrees to use its Commercially
            Reasonable Efforts to obtain and maintain, during the term of this
            Agreement, Commercial General Liability Insurance, including
            Products Liability Insurance, with reputable and financially secure
            insurance carriers to cover its indemnification obligations under
            Sections 12.1 or 12.2, as applicable, or self-insurance, with limits
            of not less than five million dollars ($5,000,000.00) per occurrence
            and in the aggregate.

13.  MISCELLANEOUS.

     13.1   Assignment. Neither this Agreement nor any interest hereunder shall
            be assignable by either Party without the prior written consent of
            the other Party, except for assignment in connection with a Change
            of Control of a Party. This Agreement shall be binding upon the
            successors and permitted assigns of the Parties and the name of a
            Party appearing herein shall be deemed to include the names of such
            Party's successors and permitted assigns to the extent necessary to
            carry out the intent of this Agreement. Any assignment not in
            accordance with this Section 13.1 shall be void.

     13.2   Further Actions. Each Party agrees to execute, acknowledge and
            deliver such further instruments, and to do all such other acts, as
            may be necessary or appropriate in order to carry out the purposes
            and intent of the Agreement.

     13.3   Force Majeure. Neither Party shall be liable to the other for delay
            or failure in the performance of the obligations on its part
            contained in this Agreement if and to the extent that such failure
            or delay is due to circumstances beyond its control which it could
            not have avoided by the exercise of reasonable diligence. It shall
            notify the other Party promptly

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<PAGE>

            should such circumstances arise, giving an indication of the likely
            extent and duration thereof, and shall use all Commercially
            Reasonable Efforts to resume performance of its obligations as soon
            as practicable, provided, however, that neither Party shall be
            required to settle any labor dispute or disturbance. Actions taken
            by a Party to resume performance of its obligations with respect to
            Screening, Research and Development matters shall be taken in
            consultation with the JSC, and actions taken by a Party to resume
            performance of its Commercialization obligations in the Copromotion
            Territory shall be taken in consultation with the MSC.

     13.4   Correspondence and Notices.

            13.4.1 Ordinary Notices. Correspondence, reports, documentation, and
                   any other communication in writing between the Parties in the
                   course of ordinary implementation of this Agreement shall be
                   delivered by hand, sent by facsimile transmission (receipt
                   verified), or by airmail to the employee or representative of
                   the other Party who is designated by such other Party to
                   receive such written communication.

            13.4.2 Extraordinary Notices. Extraordinary notices and other
                   communications hereunder (including, without limitation, any
                   notice of force majeure, breach, termination, change of
                   address, exercise of rights to negotiate additional
                   agreements, etc.) shall be in writing and shall be deemed
                   given if delivered personally or by facsimile transmission
                   (receipt verified), mailed by registered or certified mail
                   (return receipt requested), postage prepaid, or sent by
                   nationally recognized express courier service, to the Parties
                   at the following addresses (or at such other address for a
                   Party as shall be specified by like notice, provided,
                   however, that notices of a change of address shall be
                   effective only upon receipt thereof):

                   All correspondence to Wyeth shall be addressed as follows:

                       Wyeth Pharmaceuticals
                       500 Arcola Road
                       Collegeville, Pennsylvania 19426
                       Attn: Senior Vice President, Global Business Development
                       Fax: (484) 865-6476

                            with a copy to:

                            Wyeth
                            5 Giralda Farms
                            Madison, New Jersey  07940
                            Attn: General Counsel

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<PAGE>

                            Fax: (973) 660-7156

                   All correspondence to ViroPharma shall be addressed as
                   follows:

                       ViroPharma Incorporated
                       405 Eagleview Boulevard
                       Exton, Pennsylvania 19341
                       Attn: Vice President, Business Development
                       Fax: (610) 458-7380

                            with a copy to:

                            ViroPharma Incorporated
                            405 Eagleview Boulevard
                            Exton, Pennsylvania  19341
                            Attn: General Counsel
                            Fax: (610) 458-7380

     13.5   Amendment. No amendment, modification or supplement of any provision
            of this Agreement shall be valid or effective unless made in writing
            and signed by a duly authorized officer of each Party.

     13.6   Waiver. No provision of the Agreement shall be waived by any act,
            omission or knowledge of a Party or its agents or employees except
            by an instrument in writing expressly waiving such provision and
            signed by a duly authorized officer of the waiving Party.

     13.7   Severability. If any clause or portion thereof in this Agreement is
            for any reason held to be invalid, illegal or unenforceable, the
            same shall not affect any other portion of this Agreement, as it is
            the intent of the Parties that this Agreement shall be construed in
            such fashion as to maintain its existence, validity and
            enforceability to the greatest extent possible. In any such event,
            this Agreement shall be construed as if such clause of portion
            thereof had never been contained in this Agreement, and there shall
            be deemed substituted therefor such provision as will most nearly
            carry out the intent of the Parties as expressed in this Agreement
            to the fullest extent permitted by applicable law unless doing so
            would have the effect of materially altering the right and
            obligations of the Parties in which event this Agreement shall
            terminate and all the rights and obligations granted to the Parties
            hereunder shall cease and be of no further force and effect.

     13.8   Descriptive Headings. The descriptive headings of this Agreement are
            for convenience only, and shall be of no force or effect in
            construing or interpreting any of the provisions of this Agreement.

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     13.9   Governing Law. This Agreement shall be governed by and interpreted
            in accordance with the substantive laws of the State of New Jersey,
            without regard to conflict of law principles thereof.

     13.10  Entire Agreement of the Parties. This Agreement constitutes and
            contains the complete, final and exclusive understanding and
            agreement of the Parties and cancels and supersedes any and all
            negotiations, correspondence, understandings and agreements prior to
            the Effective Date including, without limitation, the Prior
            Agreement, and including, in addition, the Letter from L. Patrick
            Gage, Ph.D., President, Wyeth Research, to Michel de Rosen,
            President and Chief Executive Officer, ViroPharma Incorporated (June
            6, 2002, and countersigned by Michel de Rosen) whether oral or
            written, among the Parties respecting the subject matter hereof and
            thereof.

     13.11  Independent Contractors. Both Parties are independent contractors
            under this Agreement. Nothing herein contained shall be deemed to
            create an employment, agency, joint venture or partnership
            relationship between the Parties hereto or any of their agents or
            employees, or any other legal arrangement that would impose
            liability upon one Party for the act or failure to act of the other
            Party. Neither Party shall have any express or implied power to
            enter into any contracts or commitments or to incur any liabilities
            in the name of, or on behalf of, the other Party, or to bind the
            other Party in any respect whatsoever.

     13.12  Debarment. Each Party agrees that it will not use, in any capacity,
            in connection with any of its obligations to be performed under the
            Research Program any individual who has been debarred under the FD&C
            Act or the Generic Drug Enforcement Act.

     13.13  Counterparts. This Agreement may be executed in any number of
            counterparts, each of which need not contain the signature of more
            than one Party but all such counterparts taken together shall
            constitute one and the same agreement.

     IN WITNESS WHEREOF, duly authorized representatives of the Parties have
duly executed this Agreement to be effective as of the Effective Date.

   WYETH                                   VIROPHARMA INCORPORATED

   By /s/ Bernard J. Poussot               By /s/ Michel de Rosen
      --------------------------------        ----------------------------
   Name:  Bernard J. Poussot               Name:  Michel de Rosen
   Title: Executive Vice President         Title: President, CEO & Chairman

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June 26, 2003       Restated & Amended Collaboration Agreement           Page 89

<PAGE>

                                   EXHIBIT 1.7

                               Wyeth PATENT RIGHTS

                                      NONE.

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<PAGE>

                                  EXHIBIT 1.18

                         CLASS A PRODUCT CHEMICAL SERIES

******************                        **********

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

*******************************           ****************

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<PAGE>

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<PAGE>

                                  EXHIBIT 1.23

                              COLLABORATION TARGETS

***********

***********

***********

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                                  EXHIBIT 1.50

                    ELEMENTS OF FULLY-ABSORBED STANDARD COSTS

The following expenses are included in Fully Absorbed Standard Costs for
purposes of this Agreement:

1.   Direct Materials

     Materials used in the manufacturing process that are traced directly to the
     completed materials, Compound or Product, as applicable, and include:

     -  Inert raw materials or excipients
     -  Active substances/ingredients at market prices
     -  Packaging components such as bottles, caps, labels, etc.

2.   Direct Labor

     The cost of employees engaged in production activities which are directly
     identifiable with manufacturing the materials, Compound or Product, as
     applicable. Excludes supervision and production support activities such as
     inspection, plant and equipment maintenance labor, and material handling
     personnel. Direct Labor cost includes:

     -  Base pay, overtime, vacation and holidays, illness, personal time with
        pay and shift differential.
     -  Cost of employee fringe benefits such as health and life insurance,
        payroll taxes, welfare, pension and profit sharing.

3.   Allocated Costs

     Costs which are allocated to manufacturing the Ingredient based on standard
     direct labor hours of the manufacturing process. These allocated costs
     include:

     -  Utilities - expenses incurred for fuel, electricity and water in
        providing power for production and other plant equipment

     -  Maintenance and repairs - amount of expense incurred in-house or
        purchased to provide services for plant maintenance and repairs of
        facilities and equipment.

     -  Depreciation - of plant and equipment utilizing the straight-line method
        of calculation.

     -  Insurance - cost of comprehensive and other insurance necessary for the
        safeguard of manufacturing plant and equipment.

--------------------------------------------------------------------------------
June 26, 2003  Restated & Amended Collaboration Agreement - Exhibit 1.50  Page 1

<PAGE>

     -  Permits and Licenses - fees payable to governmental agencies or
        authorities to obtain or maintain permits or licenses that are necessary
        for the operation of facilities used to manufacture the materials,
        Compound or Product, as applicable.

     -  Costs of the following manufacturing services

                 (degree) Purchasing and Accounting
                 (degree) Production Scheduling
                 (degree) Inventory Management
                 (degree) Plant Materials Management
                 (degree) Supervision and Production Support

        Various bases may be used for allocating these costs to manufacturing
        operating departments including headcount, square feet, metered
        utilities use, estimated services rendered, EDP computer hours, etc.

4.   Testing Costs - direct labor costs for Quality Assurance ("QA") testing and
     approving materials used in manufacturing and completed manufacturing
     batches and finished Products. This includes all manufacturing in-process
     testing and testing of finished materials. Excluded costs are QA costs
     related to research and development, stability testing, etc.

--------------------------------------------------------------------------------
June 26, 2003  Restated & Amended Collaboration Agreement - Exhibit 1.50  Page 2

<PAGE>

                                  EXHIBIT 1.114

                            VIROPHARMA PATENT RIGHTS

===============================================================================

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===============================================================================

___________________________________________

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June 26, 2003 Restated & Amended Collaboration Agreement - Exhibit 1.113  Page 1

<PAGE>

***************************************************

***************************************************

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June 26, 2003  Restated & Amended Collaboration Agreement - Exhibit 1.113 Page 2

<PAGE>

                            EXHIBIT 4.6.5(b)(ii-iii)

              SAMPLE CALCULATION OF CERTAIN RECONCILIATION AMOUNTS

***************************************************

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June 26, 2003 Restated & Amended Collaboration Agreement-Exhibit
                                                         4.6.5(b)(ii-iii) Page 1

<PAGE>

                                   EXHIBIT 5.4

                       ADVERSE EVENT REPORTING PROCEDURES

     The Parties hereby agree that the following terms will govern disclosures
of each Party to the other with respect to adverse event reporting relating to
any Development Candidate or Product as clinically tested or marketed by or on
behalf of either Party.

1.   Definitions.

     1.1   Adverse Experience or Event (AE): An AE is defined by Wyeth as any
           untoward, undesired, or unplanned event in the form of signs,
           symptoms, disease, or laboratory or physiological observations
           occurring in a human being in a temporal relationship to use of an
           Wyeth product regardless of causal relationship. This includes:

           . any clinically significant worsening of a pre-existing condition;

           . an AE occurring from overdose (i.e., a dose higher than that
             prescribed by a health care professional for clinical reasons) of
             an Wyeth product, whether accidental or intentional;

           . an AE occurring from abuse (i.e., use for non-clinical reasons) of
             an Wyeth product;

           . an AE that has been associated with the discontinuation of the use
             of an Wyeth product;

           . any failure of expected pharmacological action (for spontaneous
             reports).

           If there is any doubt whether the information constitutes an AE, the
           information will be treated as an AE.

     1.2   Serious AE: A serious AE is defined by Wyeth as an AE occurring at
           any dose that: results in death; is life-threatening (see below);
           requires inpatient hospitalization or prolongation of an existing
           hospitalization; results in a persistent or significant disability or
           incapacity (see below); results in cancer; results in a congenital
           anomaly or birth defect. Additionally, important medical events that
           may not result in death, be life-threatening, or require
           hospitalization may be considered a serious AE when, based upon
           appropriate medical judgment, they may jeopardize the patient or
           subject and may require medical or surgical intervention to prevent
           one of the outcomes listed in this definition. Examples of such
           medical events include allergic bronchospasm requiring intensive
           treatment in an emergency room or at home; blood dyscrasias or
           convulsions that do not result in hospitalization; or the development
           of drug dependency or abuse.

--------------------------------------------------------------------------------
June 26, 2003  Restated & Amended Collaboration Agreement - Exhibit 5.4   Page 1

<PAGE>

          1.2.1  Life-threatening refers to immediate risk of death as the event
                 occurred. A life-threatening experience does not include an
                 experience that, had it occurred in a more severe form, might
                 have caused death but as it actually occurred did not create an
                 immediate risk of death. For example, hepatitis that resolved
                 without evidence of hepatic failure would not be considered
                 life-threatening even though hepatitis of a more severe nature
                 can be fatal. Similarly, an allergic reaction resulting in
                 angioedema of the face would not be life-threatening, even
                 though angioedema of the larynx, allergic bronchospasm, or
                 anaphylaxis can be fatal.

          1.2.2  Disability is defined as a substantial disruption in a person's
                 ability to conduct normal life functions.

          1.2.3  For studies, all pregnancies and all overdoses will be reported
                 to GSSE in the same time frame as serious AEs.

          1.2.4  A serious AE obtained from tests in laboratory animals includes
                 any experience suggesting a significant risk for human
                 subjects, including any findings of mutagenicity,
                 teratogenicity, or carcinogenicity.

          1.2.5  If there is any doubt whether the information constitutes a
                 serious AE, the information will be treated as a serious AE.

     1.3  Non-Serious AE: is any AE which does not meet the criteria for a
          serious AE.

     1.4  Unexpected AE: An unexpected AE is one that is not listed in the
          current product labeling. The current product labeling is either the
          package insert (for marketed Wyeth products) or the current
          investigator's brochure (for investigational Wyeth products). An
          unexpected AE includes any event that may be symptomatically and
          pathophysiologically related to an event listed in the labeling, but
          differs from the labeled event because of greater severity or
          specificity. For example, hepatic necrosis would be unexpected (by
          virtue of greater severity) if the product labeling referred only to
          elevated hepatic enzymes or hepatitis. Similarly, cerebral
          thromboembolism and cerebral vasculitis would be unexpected (by virtue
          of greater specificity) if the labeling only listed cerebral vascular
          accidents.

     1.5  Product (Drug, Vaccine, Biological, Device)-Related: For the purposes
          of regulatory reporting for investigational products, an AE will be
          considered "product-related" (i.e., drug-related, vaccine-related,
          etc.) for studies if either the investigator, the Medical Monitor, the
          CR&D Clinical Project Team Medical Monitor (or designee), or the Local
          Monitor (if applicable) assesses the AE(s) as possibly, probably, or
          definitely related.

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June 26, 2003  Restated & Amended Collaboration Agreement - Exhibit 5.4   Page 2

<PAGE>

               1.   An AE will be considered "not product-related" for studies
                    if the investigator and the medical monitor(s) and the local
                    monitor (if applicable) assess the AE(s) as probably not
                    related or definitely not related, or "relationship remote."

               2.   Whenever the investigator's or monitor's assessment is
                    unknown or unclear, the AE(s) will be treated as
                    product-related for the purposes of reporting to regulatory
                    authorities.

     1.6  Protocol-Related: AEs from studies that are not product-related may
          nevertheless be considered by the investigator or the medical
          monitor(s) or the local monitor (if applicable) to be
          protocol-related. For purposes of reporting to GSSE and regulatory
          authorities, these will be reported in the same manner as
          product-related events.

     1.7  NDA Holder is defined as: An "Applicant" as defined in 21 C.F.R.
          Section 314.3(b), for regulatory approval of a Product in any
          regulatory jurisdiction, including a holder of a foreign equivalent
          thereto.

     1.8  IND Holder is defined as: A "Sponsor" as defined in 21 C.F.R. Section
          312.3(b) of an investigational new drug in any regulatory
          jurisdiction, including a holder of a foreign equivalent thereto.

     1.9  Capitalized terms not defined in this Exhibit shall have the meaning
          assigned thereto in the Agreement.

2.   With respect to any Development Candidate or Product, the Parties agree as
     follows:

     a.   All initial reports and any follow-up information (oral or written)
          for any and all Serious AEs as defined above, (other than with respect
          to animal studies) which become known to either Party (other than from
          disclosure by or on behalf of the other Party) must be communicated by
          telephone, telefax or electronically directly to the other Party
          and/or the NDA Holder, IND Holder (individually and collectively
          referred to as "Holders") within forty-eight hours of receipt of the
          information. Written confirmation of the Serious AE received by such
          Party should be sent to the other Party and/or the Holders as soon as
          it becomes available, but in any event within forty-eight hours of
          initial report of the Serious AE by such Party.

     b.   Both Parties shall exchange Medwatch and/or CIOMs forms and other
          health authority reports within forty-eight hours of submission to any
          Regulatory Authority.

     c.   All initial reports and follow-up information received for all
          Non-Serious AEs for marketed Product which become known to a Party
          (other than from disclosure by or on behalf of the other Party) must
          be communicated in writing, by telefax or

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June 26, 2003   Restated & Amended Collaboration Agreement-Exhibit 5.4   Page 3

<PAGE>

          electronically to the other Party within ten days, on Medwatch or
          CIOMs forms (where possible).

     d.   Each Party shall coordinate and cooperate with the other whenever
          practicable to prepare a single written report regarding all Serious
          and/or Non-Serious AEs, provided, however, that neither Party shall be
          obligated to delay reporting of any AE in violation of applicable law
          or regulations regarding the reporting of AEs.

3.   The Parties further agree that:

     a.   A written report be forwarded to the other Party within forty-eight
          hours of receipt by the Party making the report, for AEs for animal
          studies which suggest a potential significant risk for humans;

     b.   Each Party will give the other Party a report via a print-out or
          computer disk of all AEs reported to it and its Affiliates relating to
          any Development Candidate or Product within the last year, within
          thirty days of receipt of a request from the other Party but not more
          often than four times a year;

     c.   If either Party wishes access to AE Reports of the other Party
          relating to a Development Candidate or Product, upon request of that
          Party, the other Party shall make available its AE records relating to
          the Product or Substance (including computer disks) for viewing and
          copying by the other Party. The Parties may discuss the transfer of AE
          Reports by computer disk.

     d.   Disclosure of information hereunder by a Party to the other Party
          shall continue as long as either Party and/or its Affiliates or
          designees continue to clinically test or market a Development
          Candidate or Product.

4.   Each Party shall diligently undertake the following further obligations
     where both Parties are or will be commercializing the Development Candidate
     or Product pursuant to the Agreement and/or performing clinical trials with
     respect to the Development Candidate or Product:

     a.   Upon the Effective Date, each Party shall identify individuals who
          shall be responsible for identifying all AE reporting requirements in
          all countries of the world as set forth in the Agreement, and any
          amendments thereto;

     b.   To immediately consult with the other Party, with respect to the
          investigation and handling of any Serious AE disclosed to it by the
          other Party or by a third Party and to allow the other Party to review
          the Serious AE and to participate in the follow-up investigation;

     c.   To immediately advise the other Party of any Development Candidate
          and/or Product safety communication received from a health authority
          and consult with the other Party with respect to any Product and/or
          Substance warning, labeling change

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June 26, 2003   Restated & Amended Collaboration Agreement-Exhibit 5.4   Page 4

<PAGE>

          or change to an investigators' brochure involving safety issues
          proposed by the other Party, including, but not limited to the safety
          issues agreed to by the Parties;

     d.   To diligently handle in a timely manner the follow-up investigation
          and resolution of each AE reported to it;

     e.   To provide the other Party mutually agreed upon audit rights of its AE
          reporting system and documentation, upon prior notice, during normal
          business hours, at the expense of the auditing Party and under the
          confidentiality obligations set forth in the Agreement;

     f.   To meet in a timely fashion from time to time as may be reasonably
          required to implement the adverse event reporting and consultation
          procedures described in this Exhibit 5.4, including identification of
          those individuals in each Party's Drug Safety group who will be
          responsible for reporting to and receiving AE information from the
          other Party, and the development of a written standard operating
          procedure with respect to adverse event reporting responsibilities,
          including reporting responsibilities to investigators;

     g.   Where possible, to transmit all data electronically;

     h.   to report to each other any addenda, revisions or changes to the
          Agreement (e.g., change in territories, local regulations, addition of
          new licensors/licensees to the Agreement, etc.) which might alter the
          adverse event reporting responsibilities hereunder;

     i.   to utilize English as the language of communication and data exchange
          between the Parties;

     j.   to develop a system of exchange of documents and information if the
          Agreement involves more than two Parties;

     k.   to work together to develop an electronic system to transmit AE data.

5.   The Parties may meet after the Effective Date of the Agreement to establish
     a separate agreement for adverse event exchange which will supersede this
     Exhibit 5.4.

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June 26, 2003   Restated & Amended Collaboration Agreement-Exhibit 5.4   Page 5

<PAGE>

                                   EXHIBIT 7.3

                            STOCK PURCHASE AGREEMENT

                                  See attached.

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June 26, 2003    Restated & Amended Collaboration Agreement-Exhibit 7.3  Page 1

<PAGE>

                                  EXHIBIT 7.4.1

                   SAMPLE CALCULATION OF ROYALTY DISTRIBUTIONS

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June 26, 2003  Restated & Amended Collaboration Agreement-Exhibit 7.4.1  Page 1

<PAGE>

                                  EXHIBIT 7.5.3

                 SAMPLE CALCULATIONS OF NET PROFIT DISTRIBUTIONS

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June 26, 2003  Restated & Amended Collaboration Agreement-Exhibit 7.5.3  Page 1

<PAGE>

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June 26, 2003  Restated & Amended Collaboration Agreement-Exhibit 7.5.3  Page 2

<PAGE>

                                 EXHIBIT 10.2(a)

                    THIRD PARTY RIGHTS, TITLE OR INTEREST IN
                        VIROPHARMA INTELLECTUAL PROPERTY

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************************************************

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June 26, 2003 Restated & Amended Collaboration Agreement-Exhibit 10.2(a)  Page 1

<PAGE>

                                 EXHIBIT 10.2(b)

                              THIRD PARTY CLAIMS ON
                      VIROPHARMA PATENT RIGHTS AND KNOW-HOW

******************************************************

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June 26, 2003 Restated & Amended Collaboration Agreement-Exhibit 10.2(b)  Page 1

<PAGE>

                                 EXHIBIT 10.2(c)

                   VIROPHARMA INTELLECTUAL PROPERTY SUBJECT TO
                          GOVERNMENT FUNDING AGREEMENTS

*****************************************************************

--------------------------------------------------------------------------------
June 26, 2003  Restated & Amended Collaboration Agreement-Exhibit 10.2(c) Page 1

<PAGE>

                                 EXHIBIT 10.3(a)

                              THIRD PARTY CLAIMS ON
                        Wyeth PATENT RIGHTS AND KNOW-HOW

                                      None.

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June 26, 2003  Restated & Amended Collaboration Agreement-Exhibit 10.3(a) Page 1

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