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                                                                     Exhibit 4.2

                                                                  EXECUTION COPY

                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

                                  BY AND AMONG

                         XANODYNE PHARMACEUTICALS, INC.,

                                       AND

           THE PREFERRED STOCKHOLDERS AND WARRANTHOLDERS NAMED HEREIN

                                   ----------

                                  JUNE 20, 2007

                                   ----------

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                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

     This Amended and Restated Investor Rights Agreement (this "Agreement")
dated as of June 20, 2007 is entered into by and among Xanodyne Pharmaceuticals,
Inc., a Delaware corporation (the "Company"), the preferred stockholders named
in Exhibit A hereto (each individually, a "Preferred Stockholder" and
collectively, the "Preferred Stockholders") that are signatories to this
Agreement and the warrantholders named on Exhibit B hereto (each individually, a
"Warrantholder" and collectively, the "Warrantholders").

                                    RECITALS:

     WHEREAS, pursuant to the Series A-l Convertible Preferred Stock Purchase
Agreement (the "Purchase Agreement") dated June 20, 2007 by and among the
Company and the Purchasers (as defined therein), the Purchasers (as defined
therein) are purchasing certain shares of the Company's Series A-l Preferred
Stock (the "Financing");

     WHEREAS, as a condition precedent to the Financing, the Company, the
Preferred Stockholders and the Warrantholders desire to enter into this
Agreement (i) amending and restating that certain Investors Right Agreement, by
and among the Company and certain stockholders of the Company, dated as of July
25, 2005 (the "Original Investors Rights Agreement"), to provide for certain
arrangements with respect to the registration of shares of capital stock of the
Company under the Securities Act, the Preferred Stockholders' right of first
refusal with respect to certain issuances of securities of the Company, and
certain covenants of the Company in accordance with the terms and conditions set
forth below.

     NOW, THEREFORE, in consideration of the mutual promises and covenants
contained in this Agreement and other good and valuable consideration, the
receipt and adequacy of which are hereby acknowledged the parties hereto agree
as follows:

                                   SECTION 1

                               CERTAIN DEFINITIONS

     As used in this Agreement, the following terms shall have the following
respective meanings:

     1.1 "2005 Purchase Agreement" means the Series A-l Convertible Preferred
Stock Purchase Agreement dated July 8, 2005 by and among the Company and the
Purchasers (defined therein).

     1.2 "Affiliate" means any person or entity directly or indirectly
controlling, controlled by or under common control with another person or
entity.

     1.3 "Available Undersubscription Amount" means the difference between the
total of all Basic Amounts available for purchase by Major Stockholders pursuant
to Section 3 and the Basic Amounts subscribed for pursuant to Section 3.

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     1.4 "Basic Amount" means, with respect to a Preferred Stockholder, its pro
rata portion of the Offered Securities determined by multiplying the number of
Offered Securities by a fraction, the numerator of which is the aggregate number
of Registrable Shares then held by such Preferred Stockholder and the
denominator of which is the total number of shares of Common Stock then
outstanding (giving effect to the conversion or exercise into Common Stock of
all outstanding convertible or exercisable securities that are then convertible
or exercisable for shares of Common Stock). If no specific conversion price is
otherwise specified in the convertible security, the number of shares of Common
Stock deemed issuable upon conversion of such convertible security shall be
computed using the price per share of the most recently completed round of
equity financing.

     1.5 "By-laws" means the Company's By-laws, as amended from time to time.

     1.6 "Code" means the Internal Revenue Code of 1986, as amended.

     1.7 "Commission" means the Securities and Exchange Commission, or any other
Federal agency at the time administering the Securities Act.

     1.8 "Common Stock" means the common stock, $0.001 par value per share, of
the Company.

     1.9 "Company" has the meaning ascribed to it in the introductory paragraph
hereto.

     1.10 "Company Sale" means (a) a merger or consolidation in which (i) the
Company is a constituent party, or (ii) a Subsidiary of the Company is a
constituent party and either (x) the Company issues shares of its capital stock
pursuant to such merger or consolidation, or (y) as a result of such merger or
consolidation of a Subsidiary, the Company's ownership interest in the surviving
entity is reduced; (b) the disposition by holders of the Company's then
outstanding capital stock of at least a majority of the then outstanding equity
voting power of the Company in a single or a series of related transactions; or
(c) the sale, lease or other disposition of all or substantially all of the
assets of the Company in a single transaction or series of related transactions.

     1.11 "Exchange Act" means the Securities Exchange Act of 1934, as amended,
or any successor statute, and the rules and regulations of the Commission issued
under such Act, as they each may, from time to time, be in effect.

     1.12 "Executive Officer" means the Company's Chief Executive Officer,
President, Chief Operating Officer, Chief Financial Officer and any other
officer designated by the Board of Directors as an Executive Officer.

     1.13 "Founder" means any of the following individuals: Rolf Classon,
Stephen Stamp, Roger Griggs and Tim Wright.

     1.14 "Indemnified Party" means a party entitled to indemnification pursuant
to Section 2.6.


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     1.15 "Indemnifying Party" means a party obligated to provide
indemnification pursuant to Section 2.6.

     1.16 "Initiating Holder" means any Preferred Stockholder or Preferred
Stockholders initiating a request for registration pursuant to Section 2.1(a)
or 2.1(b), as the case may be.

     1.17 "Initial Public Offering" means the initial underwritten public
offering of shares of Common Stock pursuant to an effective Registration
Statement under the Securities Act.

     1.18 "Major Stockholder" has the meaning ascribed to it in Sections 2.1(b)
and 2.3 hereto.

     1.19 "Notice of Acceptance" means a written notice from a Major Stockholder
to the Company containing the information specified in Section 3.1(b).

     1.20 "Offer" means a written notice of any proposed or intended issuance,
sale or exchange of Offered Securities containing the information specified in
Section 3.1(a).

     1.21 "Offered Securities" means (i) any shares of Common Stock, (ii) any
other equity securities of the Company, including, without limitation, shares of
preferred stock, (iii) any option, warrant or other right to subscribe for,
purchase or otherwise acquire any equity securities of the Company or (iv) any
debt securities convertible into or exchangeable for capital stock of the
Company.

     1.22 "Prospectus" means the prospectus included in any Registration
Statement, as amended or supplemented by an amendment or prospectus supplement,
including post-effective amendments, and all material incorporated by reference
or deemed to be incorporated by reference in such Prospectus.

     1.23 "Purchase Agreement" has the meaning ascribed to it in the recitals
hereto.

     1.24 "Qualified Public Offering" means the closing of an underwritten
public offering of shares of Common Stock of the Company pursuant to an
effective Registration Statement under the Securities Act and listed on the New
York Stock Exchange or NASDAQ, in which the per share public offering price is
not less than $1.50 (subject to appropriate adjustment for stock splits, stock
dividends, combinations and other similar recapitalizations affecting such
shares), and which results in at least $50,000,000 of net proceeds to the
Company.

     1.25 "Refused Securities" means those Offered Securities as to which a
Notice of Acceptance has not been given by the Major Stockholders pursuant to
Section 3.1.

     1.26 "Registration Expenses" means all expenses incurred by the Company in
complying with the provisions of Section 2, including, without limitation, all
registration and filing fees, exchange listing fees, printing expenses, fees and
expenses of counsel for the Company and the fees and expenses of one counsel to
represent the Selling Stockholders selected by holders of a majority of the
Registrable Shares held by the Selling Stockholders, state Blue Sky fees and
expenses, and the expense of any special audits incident to or required by any
such registration, but excluding underwriting discounts, selling commissions and
the fees and


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expenses of any additional counsel to the Selling Stockholders' (other than the
counsel selected to represent all Selling Stockholders).

     1.27 "Registrable Shares" means (i) the shares of Common Stock issued or
issuable upon conversion of the then outstanding shares of Series A-l Preferred
Stock, (ii) any other shares of Common Stock, and any shares of Common Stock
issued or issuable upon the conversion or exercise of any other securities
acquired by the Preferred Stockholders after the date hereof, (iii) solely for
the purposed of Section 2.2, the shares of common stock issued upon exercise or
conversion of those certain warrants to purchase Common Stock issued pursuant to
the Second Amendment, dated as of June __, 2007, to the Financing Agreement
dated July 25, 2005, as amended, by and among the Company, the lenders listed
therein and Silver Point Finance, LLC and (iv) any other shares of Common Stock
issued in respect of such shares or securities (because of stock splits, stock
dividends, reclassifications, recapitalizations, or similar events); provided
however, that shares of Common Stock which are Registrable Shares shall cease to
be Registrable Shares upon (x) any sale of such shares pursuant to a
Registration Statement or Rule 144 under the Securities Act or (y) any sale in
any manner to a person or entity that is not entitled pursuant to Section 5 to
the rights provided by this Agreement. Wherever reference is made in this
Agreement to a request or consent of holders of a certain percentage of
Registrable Shares, the determination of such percentage shall include shares of
Common Stock issuable upon conversion of such Registrable Shares even if such
conversion has not yet been effected.

     1.28 "Registration Statement" means a registration statement filed by the
Company with the Commission for a public offering and sale of securities of the
Company (other than a registration statement on Form S-8 or Form S-4, or their
successors, or any other form for a similar limited purpose, or any registration
statement covering only securities proposed to be issued in exchange for
securities or assets of another corporation).

     1.29 "Securities Act" means the Securities Act of 1933, as amended, or any
successor Federal statute, and the rules and regulations of the Commission
issued under such Act, as they each may, from time to time, be in effect.

     1.30 "Selling Stockholder" means any Preferred Stockholder and any
Warrantholder and his, her or its successors or assigns owning Registrable
Shares included in a Registration Statement.

     1.31 "Series A-l Preferred Stock" means the Company's Series A-l
Convertible Preferred Stock, $0.001 par value per share.

     1.32 "Seventh Amended and Restated Certificate" means the Company's Seventh
Amended and Restated Certificate of Incorporation, as amended from time to time.

     1.33 "Stockholders Agreement" means the Second Amended and Restated
Stockholders' Agreement dated as of the date hereof by and among the Company and
the Stockholders (as defined therein).

     1.34 "Subsidiary" or "Subsidiaries" means any corporation, partnership,
limited liability company, trust or other entity of which the Company directly
or indirectly owns at the


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time (a) a majority of the outstanding shares of every class of voting equity
securities of such corporation, partnership, limited liability company, trust or
other entity or (b) the right to receive more than 50% of the net assets of such
entity available for distribution to the holders of outstanding stock or
ownership interests upon a liquidation or dissolution of such entity.

     1.35 "Undersubscription Amount" means, with respect to a Major Stockholder,
any additional portion of the Offered Securities attributable to the Basic
Amounts of other Major Stockholders as such Major Stockholder indicates it will
purchase or acquire should the other Major Stockholders subscribe for less than
their Basic Amounts.

                                    SECTION 2

                               REGISTRATION RIGHTS

     2.1 Required Registrations.

          (a) At any time after the Company's Initial Public Offering, the
Preferred Stockholders holding in the aggregate at least thirty-five percent
(35%) of the Registrable Shares then outstanding may request, in writing, that
the Company effect the registration on Form S-l or Form S-2 (or any successor
form) of Registrable Shares owned by such Preferred Stockholder or Preferred
Stockholders. The Company shall not register any additional shares of stock of
the Company on a Registration Statement at the same time as a demand
registration pursuant to this Section 2.1 without the prior written consent of
the Preferred Stockholders holding at least a majority of the Registrable Shares
to be included in the demand registration.

          (b) At any time after the Company becomes eligible to file a
Registration Statement on Form S-3 (or any successor form relating to secondary
offerings), any Preferred Stockholder that held greater than 8,177,284 shares of
Series A-l Preferred Stock immediately following closing of the Financing (each,
a "Major Stockholder") may request, in writing, that the Company effect the
registration on Form S-3 (or such successor form).

          (c) Upon receipt of any request for registration pursuant to Section
2.1 (a) or 2.1(b), the Company shall promptly give written notice of such
proposed registration to all other Preferred Stockholders in accordance with
Section 6.1. Such Preferred Stockholders shall have the right, by giving written
notice to the Company within 30 days after the Company provides its registration
notice, to elect to have included in such registration the number of Registrable
Shares as such Preferred Stockholders may request in such notice of election,
subject in the case of an underwritten offering to the terms of Section 2.1(d).
Thereupon, the Company shall use commercially reasonable efforts to effect the
registration on an appropriate Registration Statement of all Registrable Shares
that the Company has been requested to so register; provided however, that in
the case of a registration requested under Section 2.1(b), the Company will only
be obligated to effect such registration on Form S-3 (or any successor form).

          (d) If the Initiating Holders intend to distribute the Registrable
Shares covered by their request by means of an underwriting, they shall so
advise the Company as a part of their request made pursuant to Section 2.1 (a)
or 2.1(b), as the case may be, and the Company shall include such information in
its written notice referred to in Section 2.1(c). In such event, (i) the


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right of any other Preferred Stockholder to include its Registrable Shares in
such registration pursuant to Section 2.1(a) or 2.1(b) shall be conditioned
upon such other Preferred Stockholder's participation in such underwriting on
the terms set forth herein, and (ii) all Preferred Stockholders including
Registrable Shares in such registration shall enter into an underwriting
agreement upon customary terms with the underwriter or underwriters managing the
offering. The Company shall have the right to select the managing underwriter(s)
for any underwritten offering requested pursuant to Section 2.1(a) or (b),
subject to the approval of the Initiating Holders, which approval shall not be
unreasonably delayed or withheld. If any Preferred Stockholder who has requested
inclusion of its Registrable Shares in such registration as provided above
disapproves of the terms of the underwriting, such person may elect, by written
notice to the Company, to withdraw its Registrable Shares from such registration
and underwriting. In an underwritten offering, if the managing underwriter
advises the Company in writing that market factors require a limitation on the
number of shares to be underwritten, the number of Registrable Shares to be
included in the Registration Statement and underwriting shall be allocated among
all Preferred Stockholders requesting registration in proportion, as nearly as
practicable, to the respective number of Registrable Shares held by them on the
date of the request for registration made by the Initiating Holders pursuant to
Section 2.1(a) or 2.1(b), as the case may be. If any Preferred Stockholder
would thus be entitled to include more Registrable Shares than such Preferred
Stockholder requested to be registered, the excess shall be allocated among
other requesting Preferred Stockholders pro rata in the manner described in the
preceding sentence.

          (e) The Company shall not be required to effect more than two (2)
registrations requested by the Preferred Stockholders pursuant to Section 2.1(a)
above. The Company shall not be required to effect in any twelve (12) month
period more than three (3) registrations requested by the Major Stockholders
pursuant to Section 2.1(b) above. For purposes of this Section 2.1(e), a
Registration Statement shall not be counted (i) until such time as such
Registration Statement has been declared effective by the Commission (unless the
Initiating Holders withdraw their request for such registration (other than as a
result of information concerning the business, properties, assets or condition
(financial or otherwise) of the Company which is made known to the holders of
Registrable Shares after the date on which such registration was requested) and
elect not to pay the Registration Expenses therefor pursuant to Section 2.5) or
(ii) if (A) less than fifty percent (50%) of the total number of Registrable
Shares that Preferred Stockholders have requested to be included in such
Registration Statement are sold or (B) the Company or any other person registers
additional shares of stock of the Company on a Registration Statement at the
same time as a demand registration pursuant to this Section 2.1.

          (f) If at the time of any request to register Registrable Shares
pursuant to this Section 2.1 the Company is engaged or has plans to engage in a
registered public offering or is engaged in any other activity which, in the
good faith determination of the Company's Board of Directors, would be adversely
affected by the requested registration, then the Company may at its option
direct that such request be delayed for a period not in excess of ninety (90)
days from the effective date of such request, provided that such right to delay
a request may not be exercised by the Company more than twice in any twelve
month period, and the Company shall thereafter promptly file a Registration
Statement and cause such Registration Statement to become effective as soon as
practicable after filing.


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     2.2 Incidental Registration.

          (a) Whenever the Company proposes to file a Registration Statement,
including a Registration Statement to effect an Initial Public Offering, at any
time and from time to time, it will, prior to such filing, give written notice
to all Preferred Stockholders and Warrantholders of its intention to do so. Upon
the written request of one or more Preferred Stockholders or Warrantholders
given within fifteen (15) days after the Company provides such notice (which
request shall state the intended method of disposition of such Registrable
Shares), the Company shall use commercially reasonable efforts to cause all
Registrable Shares which the Company has been requested by such Preferred
Stockholders and Warrantholders to be registered under the Securities Act (in
the case of an Initial Public Offering, however, in an amount not to exceed 25%
of all shares of Common Stock offered in such Initial Public Offering) to the
extent necessary to permit their sale or other disposition in accordance with
the intended methods of distribution specified in the request of such Preferred
Stockholders and Warrantholders; provided that the Company shall have the right
to postpone or withdraw any registration effected pursuant to this Section 2.2
without obligation to any Preferred Stockholder or Warrantholder.

          (b) If the registration for which the Company gives notice pursuant to
Section 2.2(a) is a registered public offering involving an underwriting, the
Company shall so advise the Preferred Stockholders and Warrantholders as a part
of their written notice made pursuant to Section 2.2(a). In such event, (i) the
right of any Preferred Stockholder or Warrantholder to include his, her or its
Registrable Shares in such registration pursuant to Section 2.2 shall be
conditioned upon such Preferred Stockholder's and Warrantholder's participation
in such underwriting on the terms set forth herein, and (ii) all Preferred
Stockholders and Warrantholders including Registrable Shares in such
registration shall enter into an underwriting agreement upon customary terms
with the underwriter or underwriters selected for the underwriting by the
Company. If any Preferred Stockholder or Warrantholder who has requested
inclusion of his, her or its Registrable Shares in such registration as provided
above disapproves of the terms of the underwriting, such Preferred Stockholder
or Warrantholder may elect, by written notice to the Company, to withdraw his,
her or its Registrable Shares from such Registration Statement and underwriting.
If the managing underwriter advises the Company in writing that market factors
require a limitation on the number of shares to be underwritten, all of the
shares held by holders other than the Preferred Stockholders and Warrantholders,
including any officers, directors or employees of the Company, shall first be
excluded from such Registration Statement and underwriting to the extent deemed
advisable by the managing underwriter, and, if further reduction of the number
of shares is required, the number of shares that may be included in the
Registration Statement and underwriting shall be allocated among all Preferred
Stockholders and Warrantholders requesting registration in proportion, as nearly
as practicable, to the respective number of Registrable Shares held by them on
the date the Company gives the notice specified in Section 2.2(a); provided that
the number of Registrable Shares included in such registration on behalf of the
Preferred Stockholders and Warrantholders requesting registration shall not be
less than thirty percent (30%) of the total shares requested to be registered
(except in the case of an Initial Public Offering, in which case the number of
Registrable Shares included in such registration on behalf of the Preferred
Stockholders and Warrantholders requesting registration shall not be less than
twenty-five (25%) of the total shares registered in such offering). If any
Preferred Stockholder or Warrantholder would thus be entitled to include more
shares than such


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holder requested to be registered, the excess shall be allocated among other
requesting Preferred Stockholders and Warrantholders pro rata in the manner
described in the preceding sentence.

          2.3 Aggregation. For purposes of this Agreement, for any Preferred
Stockholder, Wararntholder or Major Stockholder that is a partnership,
corporation or limited liability company, the general partner, limited partners,
retired partners, shareholders, members, retired members and Affiliates of such
Preferred Stockholder, Warrantholder or Major Stockholder, and the general
partners, limited partners, retired partners, shareholders, members, retired
members or Affiliates of the foregoing, or investment vehicles for whom any of
the foregoing is a general partner, manager or investment advisor, as
applicable, and the estates, beneficiaries and family members of any such
general partner, limited partners, retired partners, shareholders, members, and
retired members and any trusts for the benefit of any of the foregoing persons
shall be deemed to be a single "Preferred Stockholder," "Warrantholder" or
"Major Stockholder." The determination of whether a Preferred Stockholder is a
"Major Stockholder" and the determination of any pro rata reduction pursuant to
Section 2.1(d) or 2.2(b) with respect to such Preferred Stockholder shall be
based upon the aggregate amount of Registrable Shares owned by all entities and
individuals included in such "Preferred Stockholder" or "Major Stockholder", as
defined in this section.

     2.4 Registration Procedures.

          (a) If and whenever the Company is required by the provisions of this
Agreement to use commercially reasonable efforts to effect the registration of
any Registrable Shares under the Securities Act, the Company shall
expeditiously:

               (i) prepare and file with the Commission a Registration Statement
with respect to such Registrable Shares and use commercially reasonable efforts
to cause that Registration Statement to become effective as promptly as
practicable and to keep the Registration Statement effective for up to twelve
(12) months from the effective date or such lesser period until all such
Registrable Shares are sold; provided however, that such twelve month period
shall be extended for a period of time equal to the period the Selling
Stockholders refrain from selling any securities of the Company included in such
registration at the request of an underwriter of the Company's Common Stock or
as required pursuant to Section 2.4(b) and (c);

               (ii) prepare and file with the Commission any amendments and
supplements to the Registration Statement and the Prospectus included in the
Registration Statement as may be necessary to comply with the provisions of the
Securities Act (including the anti-fraud provisions thereof);

               (iii) furnish to each Selling Stockholder such reasonable numbers
of copies of the Prospectus, including a preliminary prospectus, in conformity
with the requirements of the Securities Act, and such other documents as the
Selling Stockholder may reasonably request in order to facilitate the public
sale or other disposition of the Registrable Shares owned by such Selling
Stockholder;


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               (iv) register or qualify the Registrable Shares covered by the
Registration Statement under the securities or Blue Sky laws of such states as
the Selling Stockholders shall reasonably request; provided however, that the
Company shall not be required in connection with this subsection (iv) to qualify
as a foreign corporation or execute or file a general consent to service of
process in any jurisdiction, unless the Company is already subject to service in
such jurisdiction and except as may be required by the Securities Act;

               (v) cause all such Registrable Shares to be listed on each
securities exchange or automated quotation system on which similar securities
issued by the Company are then listed;

               (vi) provide a transfer agent and registrar for all such
Registrable Shares and a CUSIP number not later than the effective date of such
Registration Statement;

               (vii) notify each Selling Stockholder, promptly after it shall
receive notice thereof, of the time when such Registration Statement has become
effective or a supplement to any Prospectus forming a part of such Registration
Statement has been filed;

               (viii) following the effectiveness of such Registration
Statement, notify each Selling Stockholder of any request by the Commission for
the amending or supplementing of such Registration Statement or Prospectus;

               (ix) notify each Selling Stockholder of Registrable Shares
covered by such Registration Statement upon the occurrence of any event as a
result of which the Prospectus included in a Registration Statement, as then in
effect, contains an untrue statement of material fact or omits to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading in light of the circumstances then existing, and prepare,
file and furnish to each such Selling Stockholder a reasonable number of copies
of a supplement or an amendment to such Prospectus as may be necessary so that
such Prospectus does not contain an untrue statement of material fact or omit to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading in light of the circumstances then existing;
and

               (x) use commercially reasonable efforts to prevent the issuance
of any stop order or other order suspending the effectiveness of a Registration
Statement covering Registrable Shares and, if such an order is issued, to use
commercially reasonable efforts to obtain the withdrawal thereof at the earliest
possible time and to notify the Selling Stockholder of the issuance of such
order and the resolution thereof.

          (b) At the request of any Selling Stockholder at any time after any
Registrable Shares held by such Selling Stockholder become eligible for resale
pursuant to Rule 144(k) under the Securities Act, the Company shall deliver a
letter to the Company's transfer agent irrevocably instructing the transfer
agent to remove any securities law legend from any certificate representing such
Registrable Shares which have become eligible for sale pursuant to Rule 144(k).

          (c) If the Company has delivered a Prospectus to the Selling
Stockholders and after having done so the Prospectus is amended to comply with
the requirements of the Securities


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Act, the Company shall promptly notify the Selling Stockholders and, if
requested, the Selling Stockholders shall immediately cease making offers of
Registrable Shares and return all Prospectuses to the Company. The Company shall
promptly provide the Selling Stockholders with revised Prospectuses and,
following receipt of the revised Prospectuses, the Selling Stockholders shall be
free to resume making offers of the Registrable Shares.

          (d) In the event that, in the reasonable judgment of the Company, it
is advisable to suspend use of a Prospectus included in a Registration Statement
due to pending material developments or other events that have not yet been
publicly disclosed and as to which the Company believes public disclosure would
be detrimental to the Company, the Company shall notify all Selling Stockholders
to such effect, and, upon receipt of such notice, each such Selling Stockholder
shall immediately discontinue any sales of Registrable Shares pursuant to such
Registration Statement until such Selling Stockholder has received copies of a
supplemented or amended Prospectus or until such Selling Stockholder is advised
in writing by the Company that the then current Prospectus may be used and has
received copies of any additional or supplemental filings that are incorporated
or deemed incorporated by reference in such Prospectus. Notwithstanding anything
to the contrary herein, the Company shall not exercise its rights under this
Section 2.4(c) to suspend sales of Registrable Shares for a period in excess of
60 calendar days consecutively or 180 calendar days in the aggregate in any
365-day period.

     2.5 Allocation of Expenses. The Company shall pay all Registration Expenses
of all registrations under this Agreement; provided however, that if a
registration under Section 2.1(a) is withdrawn at the request of the Initiating
Holders holding a majority of the shares requested by such Initiating Holders to
be so registered and if such Initiating Holders elect not to have such
registration counted as a registration requested under Section 2.1(a), the
Selling Stockholders shall pay the Registration Expenses of such registration
pro rata in accordance with the number of their Registrable Shares included in
such registration; provided further however, that if at the time of such
withdrawal, the Initiating Holders have either (i) learned material adverse
information concerning the business, properties, assets or condition (financial
or otherwise) of the Company which is made known to the Selling Stockholders
after the date on which such registration was requested and materially impacts
the Offering or (ii) been informed by the underwriters of such registration that
more than twenty-five percent (25%) of the Registrable Shares requested for
registration shall not be included therein due to market factors, and in either
such case the Initiating Holders have withdrawn the request with reasonable
promptness following such disclosure, then the Selling Stockholders shall not be
required to pay the Registration Expenses and shall retain all of their rights,
including their demand and incidental registration rights pursuant to Sections
2.1 and 2.2.

     2.6 Indemnification and Contribution.

          (a) In the event of any registration of any of the Registrable Shares
under the Securities Act pursuant to this Agreement, the Company will indemnify
and hold harmless each Selling Stockholder, each underwriter of such Registrable
Shares, and each other person, if any, who controls such Selling Stockholder or
underwriter within the meaning of the Securities Act or the Exchange Act against
any losses, claims, damages or liabilities, joint or several, to which such
Selling Stockholder, underwriter or controlling person may become subject under
the


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Securities Act, the Exchange Act, state securities or Blue Sky laws or
otherwise, insofar as such losses, claims, damages or liabilities (or actions in
respect thereof) arise out of or are based upon (i) any untrue statement or
alleged untrue statement of a material fact contained in any Registration
Statement under which such Registrable Shares were registered under the
Securities Act, any preliminary prospectus or final prospectus contained in the
Registration Statement, or any amendment or supplement to such Registration
Statement, (ii) the omission or alleged omission to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading, or (iii) any violation or alleged violation by the Company of the
Securities Act, the Exchange Act, any state securities law or any rule or
regulation promulgated under the Securities Act, the Exchange Act or any state
securities law in connection with the Registration Statement or the offering
contemplated thereby; and the Company will reimburse such Selling Stockholder,
underwriter and each such controlling person for any legal or any other expenses
reasonably incurred by such Selling Stockholder, underwriter or controlling
person in connection with investigating or defending any such loss, claim,
damage, liability or action; provided however, that the Company will not be
liable in any such case to the extent that any such loss, claim, damage or
liability arises out of or is based upon any untrue statement or omission made
in such Registration Statement, preliminary prospectus or final prospectus, or
any such amendment or supplement, in reliance upon and in conformity with
information furnished to the Company, in writing, by or on behalf of such
Selling Stockholder, underwriter or controlling person specifically for use in
the preparation thereof.

          (b) In the event of any registration of any of the Registrable Shares
under the Securities Act pursuant to this Agreement, each Selling Stockholder,
severally and not jointly, will indemnify and hold harmless the Company, each of
its directors and officers and each underwriter (if any) and each person, if
any, who controls the Company or any such underwriter within the meaning of the
Securities Act or the Exchange Act, against any losses, claims, damages or
liabilities, joint or several, to which the Company, such directors and
officers, underwriter or controlling person may become subject under the
Securities Act, Exchange Act, state securities or Blue Sky laws or otherwise,
insofar as such losses, claims, damages or liabilities (or actions in respect
thereof) arise out of or are based upon (i) any untrue statement or alleged
untrue statement of a material fact contained in any Registration Statement
under which such Registrable Shares were registered under the Securities Act,
any preliminary prospectus or final prospectus contained in the Registration
Statement, or any amendment or supplement to the Registration Statement, or (ii)
any omission or alleged omission to state a material fact required to be stated
therein or necessary to make the statements therein not misleading, if and to
the extent (and only to the extent) that the statement or omission was made
solely in reliance upon and in conformity with information relating to such
Selling Stockholder furnished in writing to the Company by or on behalf of such
Selling Stockholder specifically for use in connection with the preparation of
such Registration Statement, prospectus, amendment or supplement; provided
however, that the obligations of each such Selling Stockholder hereunder shall
be limited to an amount equal to the net proceeds received by such Selling
Stockholder of Registrable Shares sold in connection with such registration.

          (c) Each Indemnified Party shall give notice to the Indemnifying Party
promptly after such Indemnified Party has actual knowledge of any claim as to
which indemnity may be sought, and shall permit the Indemnifying Party to assume
the defense of any such claim or any litigation resulting therefrom; provided,
that counsel for the Indemnifying Party, who


                                       11

<PAGE>

shall conduct the defense of such claim or litigation, shall be approved by the
Indemnified Party (whose approval shall not be unreasonably withheld,
conditioned or delayed); and, provided further, that the failure of any
Indemnified Party to give notice as provided herein shall not relieve the
Indemnifying Party of its obligations under this Section 2.6 except to the
extent that the Indemnifying Party is adversely affected by such failure. The
Indemnified Party may participate in such defense at such party's expense;
provided however, that the Indemnifying Party shall pay such expense if
representation of such Indemnified Party by the counsel retained by the
Indemnifying Party would be inappropriate due to actual or potential differing
interests between the Indemnified Party and any other party represented by such
counsel in such proceeding; provided further, that in no event shall the
Indemnifying Party be required to pay the expenses of more than one law firm per
jurisdiction as counsel for the Indemnified Party. The Indemnifying Party shall
also be responsible for the expenses of such defense if the Indemnifying Party
does not elect to assume such defense. No Indemnifying Party, in the defense of
any such claim or litigation shall, except with the consent of each Indemnified
Party, consent to entry of any judgment or enter into any settlement which does
not include as an unconditional term thereof the giving by the claimant or
plaintiff to such Indemnified Party of a release from all liability in respect
of such claim or litigation, and no Indemnified Party shall consent to entry of
any judgment or settle such claim or litigation without the prior written
consent of the Indemnifying Party, which consent shall not be unreasonably
withheld, conditioned or delayed.

          (d) An underwriter shall not be entitled to indemnification pursuant
to this Section 2.6 in the event that it fails to deliver to any Selling
Stockholder any preliminary or final or revised Prospectus, as required by the
rules and regulations of the Commission.

          (e) In order to provide for just and equitable contribution to joint
liability under the Securities Act in circumstances in which the indemnification
provided for in this Section 2.6 is due in accordance with its terms but for any
reason is held to be unavailable to an Indemnified Party in respect to any
losses, claims, damages and liabilities referred to herein, then the
Indemnifying Party shall, in lieu of indemnifying such Indemnified Party,
contribute to the amount paid or payable by such Indemnified Party as a result
of losses, claims, damages or liabilities to which such party may be subject in
such proportions as is appropriate to reflect the relative fault of the Company
on the one hand and the Selling Stockholders on the other in connection with the
statements, omissions or violations which resulted in such losses, claims,
damages or liabilities, as well as any other relevant equitable considerations.
The relative fault of the Company and the Selling Stockholders shall be
determined by reference to, among other things, whether the untrue or alleged
untrue statement of material fact related to information supplied by the Company
or the Selling Stockholders and the parties' relative intent, knowledge, access
to information and opportunity to correct or prevent such statement or omission.
The Company and the Selling Stockholders agree that it would not be just and
equitable if contribution pursuant to this Section 2.6(e) were determined by pro
rata allocation or by any other method of allocation which does not take account
of the equitable considerations referred to above. Notwithstanding the
provisions of this Section 2.6(e), (i) in no case shall any one Selling
Stockholder be liable or responsible for any amount in excess of the net
proceeds received by such Selling Stockholder from the offering of Registrable
Shares and (ii) the Company shall be liable and responsible for at least any
amount in excess of such proceeds; provided however that no person guilty of
fraudulent misrepresentation (within the meaning of


                                       12

<PAGE>

Section 11(f) of the Securities Act) shall be entitled to contribution from any
person or entity who is not guilty of such fraudulent misrepresentation. Any
party entitled to contribution will, promptly after receipt of notice of
commencement of any action, suit or proceeding against such party in respect of
which a claim for contribution may be made against another party or parties
under this Section 2.6(e), notify such party or parties from whom contribution
may be sought, but the omission so to notify such party or parties from whom
contribution may be sought shall not relieve such party from any other
obligation it or they may have thereunder or otherwise under this Section
2.6(e). No party shall be liable for contribution with respect to any action,
suit, proceeding or claim settled without its prior written consent, which
consent shall not be unreasonably withheld, conditioned or delayed.

          (f) The rights and obligations of the Company and the Selling
Stockholders under this Section 2.6 shall survive the termination of this
Agreement.

     2.7 Other Matters with Respect to Underwritten Offering. In the event that
Registrable Shares are sold pursuant to a Registration Statement in an
underwritten offering pursuant to Section 2.1, the Company agrees to (a) enter
into an underwriting agreement containing customary representations and
warranties with respect to the business and operations of an issuer of the
securities being registered and customary covenants and agreements to be
performed by the Company, including without limitation customary provisions with
respect to indemnification by the Company of the underwriters of such offering;
(b) use commercially reasonable efforts to cause its legal counsel to render
customary opinions to the underwriters with respect to the Registration
Statement; and (c) use commercially reasonable efforts to cause its independent
public accounting firm to issue customary "cold comfort letters" to the
underwriters with respect to the Registration Statement.

     2.8 Information by Holder. Each Selling Stockholder shall furnish to the
Company such information regarding such holder and the distribution proposed by
such holder as the Company may reasonably request in writing and as shall be
required in connection with any registration, qualification or compliance
referred to in this Agreement.

     2.9 Market "Stand-Off" Agreement. Each Preferred Stockholder and
Warrantholder, if requested by the Company and the managing underwriter of an
underwritten public offering by the Company of Common Stock, shall not sell or
otherwise transfer or dispose of any Registrable Shares or other securities of
the Company (excluding securities acquired in the Initial Public Offering or in
the public market after such offering) held by such Preferred Stockholder and
Warrantholder for a period specified by the managing underwriter of an
underwritten public offering by the Company, which period shall not exceed 180
days following the effective date of a Registration Statement of the Company
filed under the Securities Act; provided that, (a) such agreement shall only
apply to the Initial Public Offering of the Company, (b) such agreement shall
not apply to any Registrable Securities included in the Initial Public Offering
of the Company pursuant to the terms hereof and (c) all stockholders of the
Company then holding at least 1% of the outstanding shares of Common Stock (on
an as-converted basis) and all officers and directors of the Company enter into
similar agreements. Any discretionary waiver or termination of the restrictions
of such agreements (including this Agreement) by the Company or the managing
underwriter shall apply to all persons subject to such agreements on a pro rata
basis, based upon the number of shares held by such persons. Each Preferred
Stockholder and


                                       13

<PAGE>

Warrantholder agrees to execute and deliver such other agreements as may be
reasonably requested by the Company and/or the managing underwriter(s) which are
consistent with the foregoing or which are necessary to give further effect
thereto. In order to enforce the foregoing covenant, the Company may impose
stop-transfer instructions with respect to such Capital Stock subject to the
foregoing restriction until the end of such lock-up period. The underwriters of
any class of the Company's capital stock are intended third party beneficiaries
of this Section 2.9 and shall have the right, power and authority to enforce the
provisions hereof as though they were parties hereto.

     2.10 Limitations on Subsequent Registration Rights. Except with respect to
assignees as contemplated by Section 5 hereof, the Company shall not, without
the prior written consent of Preferred Stockholders holding at least sixty
percent (60%) of the Registrable Shares, enter into any agreement with any
holder or prospective holder of any securities of the Company which would allow
such holder or prospective holder to include securities of the Company in any
Registration Statement.

     2.11 Rule 144 Requirements. After the earliest of (i) the closing of the
sale of securities of the Company pursuant to a Registration Statement, (ii) the
registration by the Company of a class of securities under Section 12 of the
Exchange Act, or (iii) the issuance by the Company of an offering circular
pursuant to Regulation A under the Securities Act, the Company agrees to:

          (a) comply with the requirements of Rule 144(c) under the Securities
Act with respect to current public information about the Company;

          (b) file with the Commission in a timely manner all reports and other
documents required of the Company under the Securities Act and the Exchange Act
(at any time after it has become subject to such reporting requirements); and

          (c) furnish to any holder of Registrable Shares upon request (i) a
written statement by the Company as to its compliance with the requirements of
said Rule 144(c), and the reporting requirements of the Securities Act and the
Exchange Act (at any time after it has become subject to such reporting
requirements), (ii) a copy of the most recent annual or quarterly report of the
Company, and (iii) such other reports and documents of the Company as such
holder may reasonably request to avail itself of any similar rule or regulation
of the Commission allowing it to sell any such securities without registration.

     2.12 Company Sale. The Company shall not, directly or indirectly, enter
into any Company Sale in which the Company shall not be the surviving
corporation unless the proposed surviving corporation shall, prior to such
Company Sale, agree in writing to assume the obligations of the Company under
this Agreement, and for that purpose references hereunder to "Registrable
Shares" shall be deemed to be references to the securities which the Preferred
Stockholders would be entitled to receive in exchange for Registrable Shares
under any such Company Sale; provided however, that (i) the provisions of this
Section 2.12 may be waived by the holders of at least sixty percent (60%) of the
then outstanding Registrable Securities and (ii) the provisions of this Section
2.12 shall not apply in the event of any Company Sale in which the Company is
not the surviving corporation if all Preferred Stockholders are entitled to
receive in


                                       14

<PAGE>

exchange for their Registrable Shares consideration consisting solely of (i)
cash, (ii) securities of the acquiring corporation which may be immediately sold
to the public without registration under the Securities Act, or (iii) securities
of the acquiring corporation which the acquiring corporation has agreed to use
its best efforts to register within 90 days of completion of the transaction for
resale to the public pursuant to the Securities Act.

     2.13 Termination. All of the Company's obligations to register Registrable
Shares under this Agreement shall terminate on the earlier of (i) the seventh
year anniversary of the consummation of the Initial Public Offering or (ii) the
date on which no Preferred Stockholder or Warrantholder holds any Registrable
Shares.

                                    SECTION 3

                              PARTICIPATION RIGHTS

     3.1 Participation Rights.

          (a) The Company shall not issue, sell or exchange, agree to issue,
sell or exchange, or reserve or set aside for issuance, sale or exchange, any
Offered Securities (excluding those described in Section 3.1(h)), unless in each
such case the Company shall have first complied with this Section 3.1. The
Company shall deliver to each Major Stockholder an Offer, which shall (i)
identify and describe the Offered Securities, (ii) describe the price and other
terms upon which they are to be issued, sold or exchanged, and the number or
amount of the Offered Securities to be issued, sold or exchanged, (iii) identify
the persons or entities to which or with which the Offered Securities are to be
offered, issued, sold or exchanged and (iv) offer to issue and sell to or
exchange with such Major Stockholder such Major Stockholder's Basic Amount and
Undersubscription Amount. Each Major Stockholder shall have the right, for a
period of fifteen (15) days following delivery of the Offer, to purchase or
acquire, at a price and upon the other terms specified in the Offer, up to the
number or amount of the Offered Securities described above. The Offer by its
terms shall remain open and irrevocable for such 15-day period.

          (b) To accept an Offer, in whole or in part, a Major Stockholder must
deliver a Notice of Acceptance to the Company prior to the end of the 15-day
period of the Offer, setting forth the portion of the Major Stockholder's Basic
Amount that such Major Stockholder elects to purchase and, if such Major
Stockholder shall elect to purchase all of its Basic Amount, the
Undersubscription Amount (if any) that such Major Stockholder elects to
purchase. If the Basic Amounts subscribed for by all Major Stockholders are less
than the total of all Basic Amounts available for purchase, then each Major
Stockholder who has set forth Undersubscription Amounts in its Notice of
Acceptance shall be entitled to purchase, in addition to the Basic Amounts
subscribed for, the Undersubscription Amount it has subscribed for; provided
however, that should the Undersubscription Amounts subscribed for exceed the
Available Undersubscription Amount, each Major Stockholder who has subscribed
for any Undersubscription Amount shall be entitled to purchase only that portion
of the Available Undersubscription Amount as the Undersubscription Amount
subscribed for by such Major Stockholder bears to the total Undersubscription
Amounts subscribed for by all Major

                                       15

<PAGE>

Stockholders, subject to rounding by the Board of Directors to the extent it
reasonably deems necessary.

          (c) The Company shall have 90 days from the expiration of the 15-day
period set forth in Section 3.1 (a) above to issue, sell or exchange all or any
part of the Refused Securities, but only to the offerees or purchasers described
in the Offer and only upon terms and conditions (including, without limitation,
unit prices and interest rates) which are not more favorable, in the aggregate,
to the acquiring person or persons or less favorable, in the aggregate, to the
Company than those set forth in the Offer.

          (d) In the event the Company shall propose to sell less than all the
Refused Securities (any such sale to be in the manner and on the terms specified
in Section 3.1(c) above), then each Major Stockholder may, at his, her or its
sole option and in his, her or its sole discretion, reduce the number or amount
of the Offered Securities specified in his, her or its Notice of Acceptance to
an amount that shall be not less than the number or amount of the Offered
Securities that the Major Stockholder elected to purchase pursuant to Section
3.1(b) above multiplied by a fraction, (i) the numerator of which shall be the
number or amount of Offered Securities the Company actually proposes to issue,
sell or exchange (including Offered Securities to be issued or sold to Major
Stockholders pursuant to Section 3.1(b) above prior to such reduction) and (ii)
the denominator of which shall be the original amount of the Offered Securities.
In the event that any Major Stockholder so elects to reduce the number or amount
of Offered Securities specified in his, her or its Notice of Acceptance, the
Company may not issue, sell or exchange more than the reduced number or amount
of the Offered Securities unless and until such securities have again been
offered to the Major Stockholders in accordance with Section 3.1(a) above.

          (e) Upon the closing of the issuance, sale or exchange of all of the
Refused Securities or less than all, in accordance with Section 3.1(d), of the
Refused Securities, the Major Stockholders shall acquire from the Company, and
the Company shall issue to the Major Stockholders, the number or amount of
Offered Securities specified in the Notices of Acceptance, as reduced pursuant
to Section 3.1(d) above if the Major Stockholders have so elected, upon the
terms and conditions specified in the Offer.

          (f) The purchase by the Major Stockholders of any Offered Securities
is subject in all cases to the preparation, execution and delivery by the
Company and the Major Stockholders of a purchase agreement relating to such
Offered Securities reasonably satisfactory in form and substance to the Company,
the Major Stockholders and their respective counsel.

          (g) Any Offered Securities not acquired by the Major Stockholders or
other persons in accordance with Section 3.1(c) above may not be issued, sold or
exchanged until they are again offered to the Major Stockholders under the
procedures specified in this Agreement.

          (h) The rights of the Major Stockholder under this Section 3 shall not
apply to:

               (i) shares of Series A-l Preferred Stock issued pursuant to the
Purchase Agreement;


                                       16

<PAGE>

               (ii) shares of Common Stock issuable upon conversion of shares of
Series A-l Preferred Stock;

               (iii) shares of Common Stock issued upon conversion of any
debenture, warrant, option or other convertible security that is outstanding on
the date of this Agreement (including up to 5,119,139 shares of Common Stock (as
may be adjusted in the event of any stock dividend, stock split, combination or
other similar recapitalization affecting shares of Common Stock) issued upon
exercise of warrants granted in connection with certain credit facilities on the
date of this Agreement);

               (iv) shares of Common Stock issued as a dividend or distribution
on the Series A-l Preferred Stock;

               (v) shares of Common Stock issued or deemed issued by reason of a
dividend, stock split, split-up or other distribution on shares of Common Stock;

               (vi) up to an aggregate of 15,204,427 shares of Common Stock (or
options or other rights with respect thereto, including shares of Common Stock
issuable upon exercise thereof) (subject in either case to appropriate
adjustment for any stock dividend, stock split, combination or similar
recapitalization affecting such shares), issued to employees or directors of, or
consultants to, the Company or any of its subsidiaries pursuant to a plan,
agreement or arrangement approved by a majority of the members of the Board of
Directors of the Corporation;

               (vii) up to an aggregate of 5,000,000 shares of Common Stock
(subject to appropriate adjustment for any stock dividend, stock split,
combination or similar recapitalization affecting such shares), issued in
connection with the Company's acquisition of any business or assets used in a
business;

               (viii) up to 35,437 shares of Series A-l Preferred Stock (as may
be adjusted in the event of any stock, dividend, stock split, combination or
similar recapitalization affecting shares of Series A-l Preferred Stock) issued
to Silicon Valley Bank;

               (ix) up to 6,600,000 shares of Series A-l Preferred Stock to be
issued in connection with a merger or acquisition of product(s) approved by the
holders of at least sixty percent (60%) of the then outstanding shares of Series
A-l Preferred Stock; and

               (x) shares of Common Stock issued in a Qualified Public Offering.

     3.2 Directed Shares. In the event that an Initial Public Offering is
consummated at least one year after the closing of the Financing, the Company
will use its reasonable best efforts to cause the managing underwriter(s) of
such Initial Public Offering to designate a number of shares equal to ten
percent (10%) of the Company's shares of Common Stock to be offered in such
Initial Public Offering for sale under a "directed shares program" and shall
instruct such underwriter(s) to allocate no less than fifty percent (50%) of
such directed shares program to be sold to persons or entities designated by the
Major Stockholders on a pro rata basis (based upon the number of Registrable
Shares each Major Stockholder holds relative to the number of Registrable Shares
held by all Major Stockholders). The shares designated by the underwriter(s)


                                       17

<PAGE>

for sale under a directed shares program are referred to herein as "directed
shares." The Major Stockholders acknowledge that, despite the Company's use of
its reasonable best efforts, the underwriter(s) may determine in their sole
discretion that it is not advisable to designate all such shares as directed
shares in the Initial Public Offering, in which case the number of designated
shares may be reduced or no directed shares may be designated, as applicable;
provided that such determination by such underwriter shall be made in writing
and furnished to the Major Stockholders. The Major Stockholders also acknowledge
that notwithstanding the terms of this Agreement, the sale of any directed
shares to any person or entity pursuant to this Agreement will only be made in
compliance with Rule 2110 of the National Association of Securities Dealers,
Inc. Conduct Rules and federal, state and local laws, rules and regulations and
only if the Initial Public Offering is consummated after one year from the date
hereof.

     3.3 Termination. Sections 3.1 and 3.2 hereof shall terminate upon the
earlier of the closing of a Company Sale or immediately following the
consummation of the Initial Public Offering.

                                    SECTION 4

                            COVENANTS OF THE COMPANY

     4.1 Affirmative Covenants. So long as any shares of Series A-l Preferred
Stock are outstanding, the Company covenants and agrees that, subject to waiver
or amendment in accordance with Section 6.4 below, it will perform and observe
the following covenants and provisions, and will cause each Subsidiary, if and
when such Subsidiary exists, to perform and observe such of the following
covenants and provisions as are applicable to such Subsidiary:

          (a) Payment of Taxes. The Company and each Subsidiary will pay and
discharge all lawful taxes, assessments and governmental charges or levies
imposed upon it or upon its income or property before the same shall become
overdue; provided, however, that the Company or any Subsidiary shall not be
required to pay and discharge any such tax, assessment, charge, levy, or claim
so long as the validity thereof is being contested by the Company or any
Subsidiary in good faith by appropriate proceedings if the Company or Subsidiary
shall have set aside on its books sufficient reserves, if any, with respect
thereto or where the failure to so pay would not have a material adverse effect
on the business, properties, assets or condition (financial or otherwise) of the
Company or its Subsidiaries. All transfer, excise or other taxes payable to any
jurisdiction (in the United States and outside of the United States) and/or by
reason of the sale or issuance of the shares of Series A-l Preferred Stock
(except for such taxes payable by reason of any subsequent transfer of the
shares of Series A-l Preferred Stock) shall be paid or provided for by the
Company. The preparation of such returns shall be at the Company's expense.

          (b) Maintenance of Insurance. The Company shall maintain, or shall
cause to be maintained, valid policies of workers' compensation insurance,
product liability insurance and other insurance with responsible and reputable
insurance companies or associations in such amounts and covering such risks as
are customarily carried by companies engaged in similar businesses and owning
similar properties in the same general areas in which the Company or


                                       18

<PAGE>

such Subsidiary operates, including, without limitation, insurance against loss,
damage, fire, theft, public liability, liability associated with clinical trials
and other risks.

          (c) Conduct of Business; Preservation of Corporate Existence and
Intellectual Property Rights. The Company and each Subsidiary shall preserve and
maintain its corporate existence, rights, franchises and privileges in the
jurisdiction of its incorporation, and qualify and remain qualified, and cause
each Subsidiary to qualify and remain qualified, as a foreign corporation in
each jurisdiction in which (i) such qualification is necessary or desirable in
view of its business and operations or the ownership or lease of its properties
or (ii) the failure to so qualify would have a material adverse effect on the
business, properties, assets or condition (financial or otherwise) of the
Company or its Subsidiaries. The Company and each Subsidiary will continue to
engage principally in the businesses they conduct as of the date hereof. The
Company shall, and shall cause each Subsidiary to, secure, preserve and maintain
all Company Intellectual Property Rights (as defined in the Purchase Agreement)
owned or possessed by it, except where the failure to so secure, preserve and
maintain such Intellectual Property Rights would not have a material adverse
effect on the business, properties, assets or condition (financial or otherwise)
of the Company or its Subsidiaries.

          (d) Current Obligations. The Company and each Subsidiary shall pay,
when due, or in conformity with customary trade terms but not later than 90 days
from the due date, all lease obligations, all trade debt, and all other
indebtedness incident to the operations of the Company or its Subsidiaries,
except such as are being contested in good faith and by proper proceedings if
the Company or Subsidiary shall have set aside on its books sufficient reserves,
if any, with respect thereto or where the failure to so pay would not have a
material adverse effect on the business, properties, assets or condition
(financial or otherwise) of the Company or its Subsidiaries. The Company and
each Subsidiary will pay and discharge all lawful claims for labor, materials
and supplies which, if not paid when due, might become a lien or charge upon its
property or any part thereof.

          (e) Maintenance of Properties. The Company and each Subsidiary shall
maintain and preserve all of its tangible properties and assets necessary or
useful for the proper conduct of its business, in good repair, working order and
condition, ordinary wear and tear excepted, and except where the failure to so
preserve and maintain such property would not have a material adverse effect on
the business, properties, assets or condition (financial or otherwise) of the
Company or its Subsidiaries.

          (f) Inspection Rights. The Company shall, at any time during normal
business hours and upon reasonable prior notice to the Company, permit any Major
Stockholder, or the designated representative or agent of Major Stockholder, to
(i) visit and inspect the premises and any of the properties of the Company and
any Subsidiary, including its records and books of account (and make copies
thereof and take extracts therefrom), and (ii) discuss the affairs, finances and
accounts of the Company and any Subsidiary with its officers, directors,
employees and accountants, all at the expense of such Major Stockholder;
provided, that, the Company shall not be obligated under this Section 4.1(f)
with respect to information that the Board of Directors determines in good faith
is confidential and should not be disclosed.


                                       19

<PAGE>

          (g) Compliance with Laws. The Company and each Subsidiary shall comply
with the requirements of all applicable laws, rules, regulations and orders of
the United States or any applicable foreign jurisdiction, including of the Food
and Drug Administration or similar foreign governmental authority, in the
conduct of its business, except where noncompliance would not have a material
adverse effect on the business, properties, assets or condition (financial or
otherwise) of the Company or its Subsidiaries.

          (h) Material Changes, Litigation and FDA Notices. The Company will
promptly notify its Board of Directors of any material adverse change in the
business, properties, assets or condition (financial or otherwise) of the
Company or any Subsidiary and of any litigation or governmental proceeding or
investigation pending or, to the best knowledge of the Company, threatened
against the Company or any Subsidiary which, if adversely determined, would
materially adversely affect its present or proposed business, properties, assets
or condition (financial or otherwise) taken as a whole. The Company will also
promptly notify its Board of Directors of any facts which, if such facts had
existed as of the date hereof, would have constituted a material breach of any
representation or warranty contained in the Purchase Agreement and has had or
would reasonably be expected to have a material adverse effect on the business,
properties, assets or condition (financial or otherwise) of the Company or its
Subsidiaries. The Company will also promptly provide to its Board of Directors
written notice and copies of any material notices or correspondence from the
Food and Drug Administration or any foreign regulatory equivalent.

          (i) Confidentiality, Assignment of Inventions, Non-Competition and
Non-Solicitation Agreements. The Company will require each Founder and each
person now or hereafter employed or retained by the Company or any Subsidiary
(whether as an employee or as a consultant) with access to confidential and
proprietary information of the Company to enter into an agreement covering
confidentiality and assignment of inventions in substantially the form attached
as Exhibit J to the Purchase Agreement.

          (j) Meetings of Directors and Committees of the Board. The Company
shall hold meetings of the Company's Board of Directors on a monthly basis
during the first six months following the date of the Original Investor Rights
Agreement and thereafter not less than six (6) times per year unless otherwise
determined by a majority of the members of the Board of Directors of the
Company, but in any event not less than on a quarterly basis.

          (k) Keeping of Records and Books of Account. The Company and each
Subsidiary shall keep adequate records and books of account in which complete
entries will be made in accordance with generally accepted accounting principles
consistently applied, reflecting all financial transactions of the Company and
any Subsidiary, and in which, for each fiscal year, all proper reserves for
depreciation, depletion, returns of merchandise, obsolescence, amortization,
taxes, bad debts and other purposes in connection with its business shall be
made.

          (l) Compliance with ERISA. The Company and each Subsidiary shall
comply with all minimum funding requirements applicable to any pension, employee
benefit plans or employee contribution plans which are subject to ERISA or to
the Code, and shall comply, in all other material respects, with the provisions
of ERISA and the Code, and the rules and regulations thereunder, which are
applicable to any such plan. Neither the Company nor any Subsidiary will


                                       20

<PAGE>

permit any event or condition to exist which could permit any such plan to be
terminated under circumstances which would cause the lien provided for in
Section 4068 of ERISA to attach to the assets of the Company or any Subsidiary.

          (m) Vesting of Stock. Unless otherwise approved by a majority of the
members of the Board of Directors of the Company or a duly appointed committee
thereof, all stock options and other stock equivalents issued after the date of
this Agreement to employees, directors, consultants and other service providers
pursuant to a stock purchase or option plan or other employee stock incentive
program shall be subject to a minimum vesting schedule of at least four years,
with 25% of the shares subject thereto vesting one year after the date of the
issuance or grant of such shares, and the balance of such shares vesting no more
frequently than monthly for three years thereafter, and shall provide for
termination of vesting upon cessation of employment. With respect to any shares
of stock purchased by any such person, the Company shall have a right of first
refusal on any transfer of such shares with certain exceptions for transfers to
immediate family members and to trusts of which the holder is the trustee. With
respect to any stock equivalents that are subject to vesting, the Company shall
have a repurchase option on any unvested portion of such securities in the event
of cessation of employment or provision of services.

          (n) Stockholders' Agreement. If any person receives greater than
50,000 shares of Common Stock after the date of this Agreement (including
without limitation receipt of Common Stock upon exercise of options) (subject to
appropriate adjustment for any stock dividend, stock split, combination or
similar recapitalization affecting such shares), the Company shall cause each
such person to execute and deliver the applicable Instrument of Accession
attached to the Stockholders' Agreement.

          (o) Reservation of Conversion Stock. The Company will, upon any
increase in the number of shares of Common Stock issuable upon conversion of the
outstanding shares of Series A-l Preferred Stock, reserve additional shares of
Common Stock for issuance upon such conversion, so that the number of shares of
Common Stock so reserved will not at any time be less than the number of such
shares issuable upon such conversion.

          (p) Affiliated Transactions. All transactions by and between the
Company or its Subsidiaries and any officer, employee or stockholder of the
Company or its Subsidiaries or persons controlled by or affiliated with such
officer, employee or stockholder, shall be conducted on an arms-length basis and
shall be approved by a majority of the members of the Board of Directors of the
Company after full disclosure of the terms thereof.

     4.2 Negative Covenants. The Company covenants and agrees that, in addition
to any other vote required by law or the Company's Seventh Amended and Restated
Certificate or the By-Laws, without the prior approval of a majority of the
members of the Board of Directors of the Company, the Company shall not after
the date of this Agreement, and the Company shall not permit any Subsidiary to:

          (a) enter into any contract, agreement or license or series of related
contracts, agreements or licenses providing for payments thereunder, or make any
expenditures, in excess of $250,000, whether in a single disbursement or a
series of related disbursements, if such


                                       21

<PAGE>

contract, agreement, license or series of contracts, agreements or licenses or
expenditure is not included in the Budget (as defined below) approved by the
Board of Directors;

          (b) enter into any financing arrangement in excess of $250,000
including, without limitation, loan agreements, guarantees, credit lines,
letters of credit or capitalized leases, if such financing arrangement is not
included in the Budget (as defined below) approved by the Board of Directors;

          (c) make any loan or guarantee any indebtedness;

          (d) appoint, terminate, remove or change the compensation of any
Executive Officer;

          (e) enter into any asset purchase agreement, joint venture agreement,
licensing agreement, exclusive marketing agreement, or exclusive distribution
agreement outside the ordinary course of business;

          (f) authorize, designate, issue or agree to issue any equity or debt
security of the Company, or any security convertible into, or exercisable for,
shares of the capital stock of the Company;

          (g) take any action or enter into any other transaction outside the
ordinary course of business or effect any material change in the conduct or
operation of the Company's business that would be inconsistent with the
Company's Budget (as defined below) approved by the Board of Directors; or

          (h) enter into any line of business other than the business described
in the Company's Budget (as defined below) approved by the Board of Directors.

     4.3 Financial Statements and Other Information. The Company shall deliver
the following documents to each Major Stockholder, or the designated
representative or agent of such Major Stockholder:

          (a) not later than thirty (30) days prior to the end of each fiscal
year, a comprehensive operating budget forecasting the Company revenues,
expenses and cash position on a month-to-month basis for the upcoming fiscal
year (the "Budget") approved for such fiscal year by the Board of Directors and,
promptly after preparation, any revisions to the Budget.

          (b) as soon as practicable, but in any event within ninety (90) days
after the end of each fiscal year of the Company, audited balance sheets of the
Company and of each of its Subsidiaries as at the end of such year, together
with separate statements of income and retained earnings, statements of cash
flows and summaries of bookings and backlogs of the Company and of each of its
Subsidiaries for such year, prepared in accordance with generally accepted
accounting principles, audited by certified independent public accountants of
established national reputation selected by the Company, together with the
accountant's management letter regarding the adequacy of the audit and a
capitalization updated as of such fiscal year end.


                                       22

<PAGE>

          (c) as soon as practicable, but in any event within thirty (30) days
after the end of each of the first three fiscal quarters of the Company in each
year, unaudited balance sheets of the Company and of each of its Subsidiaries as
at the end of such quarter, together with separate statements of income and
retained earnings, statements of cash flows and summaries of bookings and
backlogs of the Company and of each of its Subsidiaries for such period and for
the current fiscal year to date, and a report from the Chief Executive Officer
or Chief Financial Officer discussing comparisons to forecasted quarterly
budgets, all in reasonable detail; and

          (d) as soon as practicable, but in any event within fifteen (15) days
after the end of each month, balance sheets of the Company and of each of its
Subsidiaries as of the end of such month, together with separate statements of
income and retained earnings, statements of cash flows and summaries of bookings
and backlogs of the Company and of each of its Subsidiaries for such month and
for the current fiscal year to date, and a report from the Chief Executive
Officer or Chief Financial Officer discussing comparisons to forecasted monthly
budgets, all in reasonable detail; and

          (e) as soon as practicable, but in any event within thirty (30) days
after the end of each fiscal quarter, a table reflecting the Company's
capitalization as of the end of such quarter, which lists stockholdings by
individual stockholder.

     The foregoing financial statements shall be prepared on a consolidated
basis if the Company has any Subsidiaries. The financial statements delivered
pursuant to clauses (c) and (d) shall be accompanied by a certificate of the
Chief Financial Officer of the Company stating that such statements have been
prepared in accordance with generally accepted accounting principles
consistently applied (except as otherwise noted therein and subject to physical
inventory and other customary year end audit adjustments) and fairly present the
financial condition of the Company at the date thereof and for the periods
covered thereby. The capitalization table delivered pursuant to clause (e) shall
be accompanied by a certificate of the Chief Financial Officer of the Company
stating that such table accurately presents the capitalization of the Company at
the date thereof.

     4.4 Director and Officer Insurance; Indemnification. The Company shall
obtain, as soon as reasonably practicable, and maintain from responsible and
reputable insurance companies or associations, Director and Officer insurance
upon terms reasonably satisfactory to the Board of Directors. In the event that
the Company or any of its successors or assigns (i) consolidates with or merges
into any other entity and shall not be the continuing or surviving corporation
or entity of such consolidation or merger or (ii) transfers or conveys all or
substantially all of its properties and assets to any person or entity, then,
and in each such case, to the extent necessary, proper provision shall be made
so that the successors and assigns of the Company assume the obligations of the
Company with respect to indemnification of members of the Board of Directors as
in effect immediately prior to such transaction, whether in the Company's
bylaws, Company's certificate of incorporation, or elsewhere, as the case may
be, and to continue such indemnification for a period of at least six (6) years
following the closing of any such merger or sale.


                                       23

<PAGE>

     4.5 Issuance of Series A-l Preferred Stock. The Company hereby agrees that
it will not, in any transaction or series of transactions, issue or sell any
shares of Series A-l Preferred Stock other than in accordance with and pursuant
to the terms of the Purchase Agreement.

     4.6 Termination of Covenants. This Section 4 shall terminate upon the
earlier of (a) the closing of a Company Sale or (b) the consummation of a
Qualified Public Offering.

                                    SECTION 5

               TRANSFERS OF RIGHTS; AGREEMENT OF THE STOCKHOLDERS

     5.1 Transfers of Shares. The rights and obligations of each Preferred
Stockholder hereunder may be assigned by such Preferred Stockholder and
Warrantholder to any person or entity to which Registrable Shares are
transferred by such Preferred Stockholder and Warrantholder in compliance with
the requirements of the Stockholders' Agreement, and for purposes of this
Agreement such transferee shall be deemed a "Preferred Stockholder" or
"Warrantholder", respectively, provided that the assignment of rights shall be
contingent upon the transferee providing written instrument to the Company
notifying the Company of such transfer and agreeing in writing to be bound by
all terms and conditions set forth in this Agreement. This Agreement may not be
assigned by the Company.

                                    SECTION 6

                                  MISCELLANEOUS

     6.1 Notices. Any notice, demand, request or delivery required or permitted
to be given pursuant to the terms of this Agreement shall be in writing and
shall be deemed given (i) when delivered personally or when sent by facsimile
transmission and confirmed by telephone or electronic transmission report (with
a hard copy to follow by mail), (ii) on the next business day after timely
delivery to a generally recognized receipted overnight courier (such as FedEx)
and (iii) on the third business day after deposit in the U.S. mail (certified or
registered mail, return receipt requested, postage prepaid), addressed to the
party at such party's address as set forth below or as subsequently modified by
written notice delivered as provided herein, as follows:

               (i) if to the Company, to:

                   Xanodyne Pharmaceuticals, Inc.
                   7300 Turfway Road
                   Suite 300
                   Florence, Kentucky 41042
                   Telephone: (879) 371-7581
                   Facsimile: (859) 371-7692
                   Attention: Thomas P. Jennings, Esq.

or at such other address or addresses as may have been furnished in writing by
the Company, with a copy to:


                                       24

<PAGE>


                   Paul R. Mattingly, Esq.
                   Dinsmore & Shohl LLP
                   255 E. 5th St., Suite 1900
                   Cincinnati, Ohio 45202
                   Telephone: (513)977-8200
                   Facsimile: (513)977-8141

               (ii) if to a Preferred Stockholder, at the address as set forth
on Exhibit A hereto or at such other address as may have been furnished in
writing by such Preferred Stockholder to the other parties hereto.

               (iii) if to a Warrantholder, at the address as set forth on
Exhibit B hereto or at such other address as may have been furnished in writing
by such Warrantholder to the other parties hereto.

     6.2 Successors and Assigns. Except as otherwise expressly provided herein,
the provisions of this Agreement shall inure to the benefit of, and be binding
upon, the respective successors, permitted assigns, heirs, executors and
administrators of the parties hereto.

     6.3 Entire Agreement. This Agreement, the Purchase Agreement, and the
Stockholders' Agreement embody the entire agreement and understanding among the
parties hereto with respect to the subject matter hereof and supersede all prior
agreements and understandings, written or oral, relating to such subject matter,
including, without limitation, that certain Original Investor Rights Agreement
and that certain Term Sheet by and among the Company and MPM BioVentures III
LLC, dated as of May 10, 2007.

     6.4 Amendments and Waivers. Except as otherwise expressly set forth in this
Agreement, any term of this Agreement may be amended or terminated and the
observance of any term of this Agreement may be waived (either generally or in a
particular instance and either retroactively or prospectively), with the written
consent of the Company and the holders of at least sixty (60) percent of the
Registrable Shares; provided that, if such amendment or waiver would
disadvantage one or more holders of Registerable Shares in a manner more adverse
than other holders of Registerable Shares, the affirmative vote or written
consent of the holders of Registerable Shares so disadvantaged shall be
required; and provided further that the rights contained in Section 3.1 hereof
may not be waived, amended or terminated without the written consent of the
Company and the holders of at least sixty-eight (68) percent of the Registrable
Shares. Any amendment, termination or waiver effected in accordance with this
Section 6.4 shall be binding on all parties hereto, even if they do not execute
such consent. No waivers of or exceptions to any term, condition or provision of
this Agreement, in any one or more instances, shall be deemed to be, or
construed as, a further or continuing waiver of any such term, condition or
provision.

     6.5 Confidentiality. Each Preferred Stockholder shall keep confidential and
shall not disclose, divulge, use or otherwise take advantage of (except as
contemplated hereunder) any confidential, proprietary or secret information that
it may obtain from the Company or any Subsidiary pursuant to financial
statements, reports and other materials and information transmitted by such
entities to such Preferred Stockholder pursuant to this Agreement or the


                                       25

<PAGE>

Purchase Agreement, or pursuant to any visitation, observation or inspection
rights granted hereunder, unless such information (i) was a matter of public
knowledge prior to the time of its disclosure by the Company to such Preferred
Stockholder; (ii) became a matter of public knowledge after the time of its
disclosure by the Company to such Preferred Stockholder through means other than
an unauthorized disclosure resulting from an act or omission by such Preferred
Stockholder; (iii) was independently developed or discovered by the Preferred
Stockholder without reference to information provided by the Company; (iv) was
or becomes available to such Preferred Stockholder on a non-confidential basis
from a third party, provided that such third party is not bound by an obligation
of confidentiality to the Company with respect to such confidential information;
or (v) is required to be disclosed to comply with applicable laws or
regulations, or with a valid order of a court or other governmental body of the
United States or any political subdivisions thereof, provided such Preferred
Stockholder takes all reasonable actions to obtain confidential treatment for
such disclosure and, if possible, to minimize the extent of such disclosure.
Notwithstanding the foregoing, each Preferred Stockholder may disclose such
information (a) to its respective partners, members, parent corporations,
subsidiaries or other affiliates, which parties shall remain bound by this
confidentiality provision; (b) to its attorneys, accountants, consultants and
other professionals to the extent necessary to obtain their services in
connection with its investment in the Company; or (c) to any prospective
purchaser of any Company securities from such Preferred Stockholder as long as
such prospective purchaser agrees in writing to be bound by the provisions of
this Section 6.5, except that such Preferred Stockholder may disclose such
confidential information for the purpose of evaluating its investment in the
Company only to any general partner, limited partner, retired partner,
shareholder, member, retired member or Affiliate of such Preferred Stockholder,
as applicable, or any general partner, limited partner, retired partner,
shareholder, member, retired member or Affiliate of the foregoing, or investment
vehicles for whom any of the foregoing serves as a general partner, manager or
investment advisor, as applicable, or the estates, beneficiaries, trustees or
family members of any such general partner, limited partner, retired partner,
shareholder, member, retired member or Affiliate, or any trusts for the benefit
of any of the foregoing persons, as long as such person or entity is advised of
the confidentiality provisions of this Agreement.

     6.6 Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original, but all of which
shall be one and the same document. Facsimile signatures may be relied upon and
shall be deemed originals for purposes of effecting the provisions of this
Agreement.

     6.7 Independent Signatures. The signatories hereto shall be entitled to the
benefits and subject to the obligations set forth in this Agreement. Each
signatory hereto acknowledges and agrees that he, she or it shall be bound by
the terms and obligations of this Agreement with and to the other signatories
regardless of whether all of the Common Stockholders or Preferred Stockholders
listed on the signature pages hereto execute this Agreement.

     6.8 Severability. The invalidity or unenforceability of any provision of
this Agreement shall not affect the validity or enforceability of any other
provision of this Agreement.


                                       26

<PAGE>

     6.9 Specific Performance. In addition to any and all other remedies that
may be available at law in the event of any breach of this Agreement, each
Preferred Stockholder shall be entitled to seek specific performance of the
agreements and obligations of the Company hereunder and to such other injunctive
or other equitable relief as may be granted by a court of competent
jurisdiction.

     6.10 Titles and Subtitles. The titles of sections and subsections of this
Agreement are for convenience of reference only and are not to be considered in
construing this Agreement.

     6.11 Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the State of Delaware and the laws of the United
States applicable therein (without giving effect to any choice or conflict of
laws provision or rule that would cause the application of the laws of any other
jurisdiction) and shall be treated in all respects as a Delaware contract.

                  [Remainder of page intentionally left blank]


                                       27

<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Amended and Restated
Investor Rights Agreement as of the date first written above.

                                        COMPANY:

                                        XANODYNE PHARMACEUTICALS, INC.


                                        By: /s/ Rolf Classon
                                            ------------------------------------
                                            Rolf Classon
                                            President and Chief Executive
                                            Officer


                                        PREFERRED STOCKHOLDERS:

                                        UNION SPRINGS, L.L.C.

                                        By: Griggs Family L.L.C., Manager


                                        By:
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member


                                        UNION SPRINGS II LLC

                                        By: Griggs Family L.L.C., Manager


                                        By:
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member


                                        UNION SPRINGS III LLC

                                        By: Griggs Family L.L.C., Manager


                                        By:
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member


                                        UNION SPRINGS V LLC

                                        By: Griggs Family L.L.C., Manager


                                        By:
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member


                                        By:
                                            ------------------------------------
                                            Roger D. Griggs

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                       28

<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Amended and Restated
Investor Rights Agreement as of the date first written above.

                                        COMPANY:

                                        XANODYNE PHARMACEUTICALS, INC.


                                        By:
                                            ------------------------------------
                                            Rolf Classon
                                            President and Chief Executive
                                            Officer


                                        PREFERRED STOCKHOLDERS:

                                        UNION SPRINGS, L.L.C.

                                        By: Griggs Family L.L.C., Manager


                                        By: /s/ Roger D. Griggs
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member


                                        UNION SPRINGS II LLC

                                        By: Griggs Family L.L.C., Manager


                                        By: /s/ Roger D. Griggs
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member


                                        UNION SPRINGS III LLC

                                        By: Griggs Family L.L.C., Manager


                                        By: /s/ Roger D. Griggs
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member


                                        UNION SPRINGS V LLC

                                        By: Griggs Family L.L.C., Manager


                                        By: /s/ Roger D. Griggs
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member


                                        By: /s/ Roger D. Griggs
                                            ------------------------------------
                                            Roger D. Griggs

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                       29

<PAGE>

                                        UNION SPRINGS VII LLC

                                        By: Griggs Family L.L.C., Manager


                                        By: /s/ Roger D. Griggs
                                            ------------------------------------
                                            Roger D. Griggs, Authorized Member

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                       30

<PAGE>


                                        BLUE CHIP IV LIMITED PARTNERSHIP

                                        By: Blue Chip Venture Company, Ltd.,
                                            General Partner


                                        By: /s/ John C. McIlwraith
                                            ------------------------------------
                                        Name: John C. McIlwraith
                                        Its:  Managing Director


                                        BLUE CHIP CAPITAL FUND II LIMITED
                                        PARTNERSHIP

                                        By: Blue Chip Venture Company, Ltd.,
                                            General Partner


                                        By: /s/ John C. McIlwraith
                                            ------------------------------------
                                        Name: John C. McIlwraith
                                        Its: Managing Director


                                        BLUE CHIP CAPITAL FUND III LIMITED
                                        PARTNERSHIP

                                        By: Blue Chip Venture Company, Ltd.,
                                            General Partner


                                        By: /s/ John C. McIlwraith
                                            ------------------------------------
                                        Name: John C. McIlwraith
                                        Its: Managing Director


                                        BLUE CHIP/UNION SPRINGS, LLC

                                        By: Blue Chip Venture Company, Ltd.,
                                            Manager


                                        By: /s/ John C. McIlwraith
                                            ------------------------------------
                                        Name: John C. McIlwraith
                                        Its: Managing Director


                                        MIAMI VALLEY VENTURE FUND L.P.

                                        By: Blue Chip Venture Company of Dayton,
                                            Ltd.
                                            Special Limited Partner


                                        By: /s/ John C. McIlwraith
                                            ------------------------------------
                                        Name: John C. McIlwraith
                                        Its: Managing Director


                                       31

<PAGE>

                                        MPM BIOVENTURES III, L.P.

                                        By: MPM BioVentures III GP, L.P., its
                                            General Partner

                                        By: MPM BioVentures III LLC, its
                                            General Partner


                                        By: /s/ Ansbert Gadicke
                                            ------------------------------------
                                        Name: Ansbert Gadicke
                                        Title: Series A Member


                                        MPM BIOVENTURES III-QP, L.P.

                                        By: MPM BioVentures III GP, L.P., its
                                            General Partner

                                        By: MPM BioVentures III LLC, its
                                            General Partner


                                        By: /s/ Ansbert Gadicke
                                            ------------------------------------
                                        Name: Ansbert Gadicke
                                        Title: Series A Member


                                        MPM BIOVENTURES III PARALLEL FUND, L.P.

                                        By: MPM BioVentures III GP, L.P., its
                                            General Partner

                                        By: MPM BioVentures III LLC, its
                                            General Partner


                                        By: /s/ Ansbert Gadicke
                                            ------------------------------------
                                        Name: Ansbert Gadicke
                                        Title: Series A Member

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                       32

<PAGE>

                                        MPM BIOVENTURES III GMBH & CO.
                                        BETEILIGUNGS KG

                                        By: MPM BioVentures III GP, L.P., in its
                                            capacity as the Managing Limited
                                            Partner

                                        By: MPM BioVentures III LLC, its
                                            General Partner


                                        By: /s/ Ansbert Gadicke
                                            ------------------------------------
                                        Name: Ansbert Gadicke
                                        Title: Series A Member


                                        MPM ASSET MANAGEMENT INVESTORS 2005
                                        BVIII LLC


                                        By: /s/ Ansbert Gadicke
                                            ------------------------------------
                                        Name: Ansbert Gadicke
                                        Title: Manager

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                       33

<PAGE>

                                     APAX EUROPE VI - A, L.P.

                                     By: Apax WW Nominee Limited -a/c AE6, as
                                         their nominee


                                     By: /s/ Adrian Beecroft   /s/ Stephen Green
                                         ---------------------------------------
                                     Name: Adrian Beecroft     Stephen Green
                                     Title: Director           Director


                                     APAX EUROPE VI - I, L.P.

                                     By: Apax WW Nominee Limited - a/c AE6,
                                         as their nominee


                                     By: /s/ Adrian Beecroft   /s/ Stephen Green
                                         ---------------------------------------
                                     Name: Adrian Beecroft     Stephen Green
                                     Title: Director           Director

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                       34

<PAGE>

                                        APAX EXCELSIOR VI, L.P.

                                        By: Apax Excelsior VI Partners, L.P.,
                                            their General Partner

                                        By: Apax Managers, Inc., its General
                                            Partner


                                        By: /s/ Peter Jeton
                                            ------------------------------------
                                        Name: Peter Jeton
                                        Title: COO


                                        APAX EXCELSIOR VI - A, C.V.

                                        By: Apax Excelsior VI Partners, L.P.,
                                            their General Partner

                                        By: Apax Managers, Inc., its General
                                            Partner


                                        By: /s/ Peter Jeton
                                            ------------------------------------
                                        Name: Peter Jeton
                                        Title: COO


                                        APAX EXCELSIOR VI - B, C.V.

                                        By: Apax Excelsior VI Partners, L.P.,
                                            their General Partner

                                        By: Apax Managers, Inc., its General
                                            Partner


                                        By: /s/ Peter Jeton
                                            ------------------------------------
                                        Name: Peter Jeton
                                        Title: COO


                                        PATRICOF PRIVATE INVESTMENT CLUB
                                        III, L.P.

                                        By: Apax Excelsior VI Partners, L.P.,
                                            their General Partner

                                        By: Apax Managers, Inc., its General
                                            Partner


                                        By: /s/ Peter Jeton
                                            ------------------------------------
                                        Name: Peter Jeton
                                        Title: COO

       [Signature Page to Amended and Restated Investor Rights Agreement]

<PAGE>

                                        PERSEUS-SOROS BYOPHARMACEUTICAL FUND,
                                        L.P.


                                        By: /s/ Jay A. Schoenfarber
                                            ------------------------------------
                                        Name: Jay A. Schoenfarber
                                        Title: Attorney-in-Fact

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                        2

<PAGE>


                                        AIG PEP III DIRECT, L.P.

                                        By: AIG Global Investment Corp., its
                                            investment adviser


                                        By: /s/ Jonathan Stearns
                                            ------------------------------------
                                        Name: Jonathan Stearns
                                        Title: Managing Director


                                        AIG PEP IV CO-INVESTMENT, L.P.

                                        By: AIG PEP IV Co-Investment GP, L.P.,
                                            its general partner

                                        By: AIG PEP IV Co-Investment GP, LLC,
                                            its general manager

                                        By: AIG Global Investment Corp., its
                                            managing member


                                        By: /s/ Jonathan Stearns
                                            ------------------------------------
                                        Name: Jonathan Stearns
                                        Title: Managing Director


                                        AIG HORIZON PARTNERS FUND, L.P.

                                        By: AIG Horizon Partners GP, L.P., its
                                            general partner

                                        By: AIG Horizon Partners, LLC, its
                                            general partner

                                        By: AIG Global Investment Corp., its
                                            managing member


                                        By: /s/ Jonathan Stearns
                                            ------------------------------------
                                        Name: Jonathan Stearns
                                        Title: Managing Director

       [Signature Page to Amended and Restated Investor Rights Agreement]

<PAGE>


                                        AIG HORIZON SIDE-BY-SIDE FUND, L.P.

                                        By: AIG Horizon SBS GP, L.P., its
                                            general partner

                                        By: AIG Horizon Partners, LLC, its
                                            general partner

                                        By: AIG Global Investment Corp., its
                                            managing member


                                        By: /s/ Jonathan Stearns
                                            ------------------------------------
                                        Name: Jonathan Stearns
                                        Title: Managing Director


                                        AIG CO-INVESTMENT FUND, L.P.

                                        By: AIG Co-Investment General Partner,
                                            L.P., its general partner

                                        By: AIG Direct Investments, LLC, its
                                            general partner

                                        By: AIG Global Investment Corp., its
                                            managing member


                                        By: /s/ Jonathan Stearns
                                            ------------------------------------
                                        Name: Jonathan Stearns
                                        Title: Managing Director

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                       2

<PAGE>

                                        AIG PRIVATE EQUITY (BERMUDA) LTD.


                                        By: /s/ Mark Waddington
                                            ------------------------------------
                                        Name: Mark Waddington
                                        Title: Treasurer

<PAGE>

                                        HEALTHCARE VENTURES VI, L.P.

                                        By: Health Care Partners VI L.P., its
                                            General Partner


                                        By: /s/ Jeffrey Steinberg
                                            ------------------------------------
                                        Name: Jeffrey Steinberg
                                        Title: Administrative Partner

       [Signature Page to Amended and Restated Investor Rights Agreement]

<PAGE>


                                        ESSEX WOODLANDS HEALTH VENTURES FUND
                                        IV, L.P.

                                        By: Essex Woodlands Health Ventures, IV,
                                            LLC, General Partner


                                        By: /s/ J L Currie
                                            ------------------------------------
                                        Name: J L Currie
                                        Title: Managing Partner


                                        ESSEX WOODLANDS HEALTH VENTURES FUND
                                        V, L.P.

                                        By: Essex Woodlands Health Ventures V,
                                            LLC, General Partner


                                        By: /s/ J L Currie
                                            ------------------------------------
                                        Name: J L Currie
                                        Title: Managing Partner

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                        2

<PAGE>




                                        COLEMAN SWENSON HOFFMAN BOOTH IV L.P.

                                        By: Its General Partner
                                            CSHB Ventures VI, L.P.


                                        By: /s/ Larry H. Coleman
                                            ------------------------------------
                                        Name: Larry H. Coleman
                                        Title: General Partner


                                        JOHNSON & JOHNSON DEVELOPMENT
                                        CORPORATION


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        MESIROW FINANCIAL


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        PAREXEL INTERNATIONAL CORPORATION


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        ----------------------------------------
                                        William A. Nuerge

       [Signature Page to Amended and Restated Investor Rights Agreement]

<PAGE>

                                        COLEMAN SWENSON HOFFMAN BOOTH, IV. L.P.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        JOHNSON & JOHNSON DEVELOPMENT
                                        CORPORATION


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        MESIROW FINANCIAL


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        PAREXEL INTERNATIONAL CORPORATION


                                        By: /s/ James F. Winschel
                                            ------------------------------------
                                        Name: James F. Winschel
                                        Title: SVP & CFO


                                        ----------------------------------------
                                        William A. Nuerge

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                        2

<PAGE>

                                        WARRANTHOLDERS:

                                        SILVER POINT CAPITAL FUND, LP


                                        By: /s/ Richard Petrilli
                                            ------------------------------------
                                        Name: Richard Petrilli
                                        Title: Authorized Signatory


                                        SILVER POINT CAPITAL OFFSHORE FUND, INC.


                                        By: /s/ Richard Petrilli
                                            ------------------------------------
                                        Name: Richard Petrilli
                                        Title: Authorized Signatory


                                        SPCP GROUP III LLC


                                        By: /s/ Richard Petrilli
                                            ------------------------------------
                                        Name: Richard Petrilli
                                        Title: Authorized Signatory

       [Signature Page to Amended and Restated Investor Rights Agreement]

<PAGE>

                                        BLUE RIDGE INVESTMENTS, LLC


                                        By: /s/ Peter Sherman
                                            ------------------------------------
                                        Name: Peter Sherman
                                        Title: Managing Director

       [Signature Page to Amended and Restated Investor Rights Agreement]


                                        2

<PAGE>

                                    EXHIBIT A

                  Names and Addresses of Preferred Stockholder

NAME AND ADDRESS OF PREFERRED STOCKHOLDERS

Union Springs, LLC
Xanodyne Pharmaceuticals, Inc.
Attn: Thomas P. Jennings
7300 Turfway Road, Suite 300
Florence, KY 41042

Union Springs II LLC
Xanodyne Pharmaceuticals, Inc.
Attn: Thomas P. Jennings
7300 Turfway Road, Suite 300
Florence, KY 41042

Union Springs III LLC
Xanodyne Pharmaceuticals, Inc.
Attn: Thomas P. Jennings
7300 Turfway Road, Suite 300
Florence, KY 41042

Union Springs V, LLC
Xanodyne Pharmaceuticals, Inc.
Attn: Thomas P. Jennings
7300 Turfway Road, Suite 300
Florence, KY 41042

Union Springs VII, LLC
Xanodyne Pharmaceuticals, Inc.
Attn: Thomas P. Jennings
7300 Turfway Road, Suite 300
Florence, KY 41042

Blue Chip IV Limited Partnership
Attn: John McIlwraith
1100 Chiquita Center
250 East Fifth Street
Cincinnati, OH 45202

<PAGE>

Blue Chip Capital Fund II Limited Partnership
Attn: John McIlwraith
1100 Chiquita Center
250 East Fifth Street
Cincinnati, OH 45202

<PAGE>

NAME AND ADDRESS OF PREFERRED STOCKHOLDERS

Blue Chip Capital Fund III Limited Partnership
Attn: John McIlwraith
100 Chiquita Center
250 East Fifth Street
Cincinnati, OH 45202

Blue Chip/Union Springs, LLC
Xanodyne Pharmaceuticals, Inc.
Attn: Thomas P. Jennings
7300 Turfway Road, Suite 300
Florence, KY 41042

Miami Valley Venture Fund L.P.
Attn: John McIlwraith
1100 Chiquita Center
250 East Fifth Street
Cincinnati, OH 45202

Roger D. Griggs
Xanodyne Pharmaceuticals, Inc.
Attn: Thomas P. Jennings
7300 Turfway Road, Suite 300
Florence, KY 41042

MPM BioVentures III, L.P.
200 Clarendon Street, 54th Floor
Boston, MA 02116

MPM BioVentures III-QP, L.P.
200 Clarendon Street, 54th Floor
Boston, MA 02116

MPM BioVentures III GmbH & Co.
Beteiligungs KG
200 Clarendon Street, 54th Floor
Boston, MA 02116

MPM BioVentures III Parallel Fund, L.P.
200 Clarendon Street, 54th Floor
Boston, MA 02116

<PAGE>

NAME AND ADDRESS OF PREFERRED STOCKHOLDERS

MPM Asset Management Investors 2005 BVIII LLC
200 Clarendon Street, 54th Floor
Boston, MA 02116

      with a copy to:

      James T. Barrett, Esq.
      Edwards Angell Palmer & Dodge LLP
      111 Huntington Avenue
      Boston, MA 02199-7613

Apax Europe VI - A, L.P.
c/o Apax Europe VI GP Co. Ltd.
PO Box 431
13-15 Victoria Road
St. Peter Port
Guernsey
Channel Islands GY1 3ZD

Apax Europe VI - 1, L.P.
c/o Apax Europe VI GP Co. Ltd.
PO Box 431
13-15 Victoria Road
St. Peter Port
Guernsey
Channel Islands GY1 3ZD

Apax Excelsior VI, L.P.
445 Park Avenue, 11th Floor
New York, NY 10022

Apax Excelsior VI-A C.V.
445 Park Avenue, 11th Floor
New York, NY 10022

Apax Excelsior VI-B C.V.
445 Park Avenue, 11th Floor
New York, NY 10022

<PAGE>

NAME AND ADDRESS OF PREFERRED STOCKHOLDERS

Patricof Private Investment Club III, L.P.
445 Park Avenue, 11th Floor
New York, NY 10022

Perseus-Soros Biopharmaceutical Fund, LP
888 Seventh Avenue, 29th Floor
New York, New York 10106

AIG PEP III Direct, L.P.
c/o AIG Global Investment Group
70 Pine Street, 28th Floor
New York, NY 10270

AIG PEP IV Co-Investment, L.P.
c/o AIG Global Investment Group
70 Pine Street, 28th Floor
New York, NY 10270

AIG Horizon Partners Fund, L.P.
c/o AIG Global Investment Group
70 Pine Street, 28th Floor
New York, NY 10270

AIG Horizon Side-By-Side Fund, L.P.
c/o AIG Global Investment Group
70 Pine Street, 28th Floor
New York, NY 10270

AIG Private Equity (Bermuda) Ltd.
Attn. Jocelyn Troake
29, Richmond Road
Pembroke, HM 08
Bermuda

<PAGE>

NAME AND ADDRESS OF PREFERRED STOCKHOLDERS

      with a copy to:

      AIG Private Equity Ltd.
      Attn. Conradin Schneider
      Baarerstr. 8
      6300 Zug
      Switzerland

AIG Co-Investment Fund, L.P.
c/o AIG Global Investment Group
70 Pine Street, 28th Floor
New York, NY 10270

Healthcare Ventures VI, L.P.
Attn: James Cavanaugh
44 Nassau Street
Princeton, NJ 08542

      with a copy to:

      Christopher S. Miller, Esq.
      Pepper Hamilton LLP
      400 Berwyn Park
      899 Cassatt Road
      Berwyn, PA 19312-1183

Essex Woodlands Health Ventures Fund V, L.P.
Attn: James Currie
190 South LaSalle Street, Suite 2800
Chicago, IL 60603

Essex Woodlands Health Ventures Fund IV, L.P.
Attn: James L. Currie
190 South LaSalle Street, Suite 2800
Chicago, IL 60603

<PAGE>

NAME AND ADDRESS OF PREFERRED STOCKHOLDERS

Coleman Swenson Hoffman Booth IV, L.P.
Attn: Larry H. Coleman
237 Second Avenue South
Franklin, TN 37064

Parexel International Corporation
Attn: Brett Davis
195 West Street
Waltham, MA 02451

                                    Exhibit B

Name and Address of Preferred Stockholders

Silver Point Capital Fund, LP
Two Greenwich Plaza, 1st Floor
Greenwich, Connecticut 06830
Attention: Ryan Vetsch

Silver Point Capital Offshore Fund, Ltd.
Two Greenwich Plaza, 1st Floor
Greenwich, Connecticut 06830
Attention: Ryan Vetsch

SPCP Group III LLC
Two Greenwich Plaza, 1st Floor
Greenwich, Connecticut 06830
Attention: Ryan Vetsch

Blue Ridge Investments, LLC
c/o Bank of America Securities
214 North Tryon Street
NC1-027-14-01
Charlotte, NC 28255
Attention: Joe Haverkamp
<PAGE>


                               AMENDMENT NO. 1 TO

                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT


         This Amendment No. 1 (the "Amendment") to the Amended and Restated
Investor Rights Agreement, dated as of June 20, 2007 (the "Agreement"), by and
among Xanodyne Pharmaceuticals, Inc., a Delaware corporation (the "Company"),
and the Preferred Stockholders and Warrantholders identified therein, is entered
into as of November 8, 2007, by and among the Company and the Preferred
Stockholders and the Warrantholders. Capitalized terms used and not otherwise
defined herein shall have the meanings ascribed to them in the Agreement.

         WHEREAS, the Company and holders of at least sixty-eight percent (68%)
of the Registrable Securities desire to amend the Agreement to increase the
number of shares of Common Stock allocated for issuance to employees or
directors of, or consultants to, the Company or any of its subsidiaries,
pursuant to a plan, agreement or arrangement approved by the Board, for which
the Major Stockholders shall not have participation rights pursuant to Section
3.1 of the Agreement;

         NOW THEREFORE, the Company and the Stockholders hereby agree as
follows:

         1.       Section 3.1(h)(vi) of the Agreement shall be amended by
deleting the number "15,204,427" and inserting in place thereof the number
"41,204,427."

         2.       Except as modified hereby, the Company and the Preferred
Stockholders and the Warrantholders agree that the Agreement shall remain in
full force and effect in accordance with its terms.

         3.       This Amendment may be executed and delivered by facsimile
signature and in two or more counterparts, each of which shall be deemed an
original, but all of which together shall constitute one and the same
instrument.

                  [Remainder of page intentionally left blank]


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      COMPANY:

                                      XANODYNE PHARMACEUTICALS, INC.



                                      By:    /s/ Stephen A. Stamp
                                             -----------------------------------
                                      Name:  Stephen A. Stamp
                                             -----------------------------------
                                      Title: Chief Financial Officer
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      UNION SPRINGS, L.L.C.

                                      By: Griggs Family L.L.C., Manager



                                      By: /s/ Roger D. Griggs
                                         ---------------------------------------
                                             Roger D. Griggs, Authorized Member


                                      UNION SPRINGS II LLC

                                      By: Griggs Family L.L.C., Manager



                                      By: /s/ Roger D. Griggs
                                         ---------------------------------------
                                         Roger D. Griggs, Authorized Member


                                      UNION SPRINGS III LLC

                                      By: Griggs Family L.L.C., Manager



                                      By: /s/ Roger D. Griggs
                                         ---------------------------------------
                                         Roger D. Griggs, Authorized Member


                                      UNION SPRINGS V LLC

                                      By: Griggs Family L.L.C., Manager



                                      By: /s/ Roger D. Griggs
                                         ---------------------------------------
                                         Roger D. Griggs, Authorized Member


                                      UNION SPRINGS VII LLC

                                      By: Griggs Family L.L.C., Manager



                                      By: /s/ Roger D. Griggs
                                         ---------------------------------------
                                         Roger D. Griggs, Authorized Member


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:


                                      /s/ Roger D. Griggs
                                      ------------------------------------------
                                      Roger D. Griggs


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      BLUE CHIP IV LIMITED PARTNERSHIP

                                      By:    Blue Chip Venture Company, Ltd.,
                                             General Partner



                                      By:    /s/ John C. McIlwraith
                                         ---------------------------------------
                                      Name:  John C. McIlwraith
                                           -------------------------------------
                                      Title: Managing Director
                                            ------------------------------------


                                      BLUE CHIP CAPITAL FUND II LIMITED
                                      PARTNERSHIP

                                      By:    Blue Chip Venture Company, Ltd.,
                                             General Partner



                                      By:    /s/ John C. McIlwraith
                                         ---------------------------------------
                                      Name:  John C. McIlwraith
                                           -------------------------------------
                                      Title: Managing Director
                                            ------------------------------------

                                      BLUE CHIP CAPITAL FUND III LIMITED
                                      PARTNERSHIP

                                      By:    Blue Chip Venture Company, Ltd.,
                                             General Partner



                                      By:    /s/ John C. McIlwraith
                                         ---------------------------------------
                                      Name:  John C. McIlwraith
                                           -------------------------------------
                                      Title: Managing Director
                                            ------------------------------------


                                      BLUE CHIP/UNION SPRINGS, LLC

                                      By:    Blue Chip Venture Company, Ltd.,
                                             Manager



                                      By:   /s/ John C. McIlwraith
                                         ---------------------------------------
                                      Name: John C. McIlwraith
                                           -------------------------------------
                                      Title: Manager
                                            ------------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      MIAMI VALLEY VENTURE FUND L.P.

                                      By:    Blue Chip Venture Company of
                                             Dayton, Ltd.,
                                             Special Limited Partner



                                      By:   /s/ John C. McIlwraith
                                         ---------------------------------------
                                      Name: John C. McIlwraith
                                           -------------------------------------
                                      Title: Manager
                                            ------------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      ESSEX WOODLANDS HEALTH VENTURES
                                      FUND IV, L.P.

                                      By:    Essex Woodlands Health Ventures IV,
                                             L.L.C., its General Partner



                                      By:    /s/ James L. Currie
                                             -----------------------------------
                                      Name:  James L. Currie
                                             -----------------------------------
                                      Title: Managing Director
                                             -----------------------------------


                                      ESSEX WOODLANDS HEALTH VENTURES
                                      FUND V, L.P.

                                      By:    Essex Woodlands Health Ventures V,
                                             L.L.C., its General Partner



                                      By:    /s/ James L. Currie
                                             -----------------------------------
                                      Name:  James L. Currie
                                             -----------------------------------
                                      Title: Managing Director
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      COLEMAN SWENSON HOFFMAN BOOTH IV, L.P.

                                      By:    CSHB Ventures IV L.P., its General
                                             Partner



                                      By:     /s/ Larry H. Coleman
                                             -----------------------------------
                                      Name:   Larry H. Coleman
                                             -----------------------------------
                                      Title:  Managing General Partner
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      HEALTH CARE VENTURES VI, L.P.

                                      By:    Health Care Partners VI, L.P., its
                                             general partner



                                      By:    /s/ James H. Cavanaugh
                                             -----------------------------------
                                      Name:  James H. Cavanaugh
                                             -----------------------------------
                                      Title: Managing Director
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      PAREXEL INTERNATIONAL CORPORATION



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      MPM BIOVENTURES III, L.P.

                                      By:    MPM BioVentures III GP, L.P., its
                                             General Partner
                                      By:    MPM BioVentures III LLC, its
                                             General Partner

                                      By: /s/ Ansbert Gadicke
                                         ---------------------------------------
                                      Name: Ansbert Gadicke
                                           -------------------------------------
                                      Title: Series A Member
                                            ------------------------------------


                                      MPM BIOVENTURES III-QP, L.P.

                                      By:    MPM BioVentures III GP, L.P., its
                                             General Partner
                                      By:    MPM BioVentures III LLC, its
                                             General Partner



                                      By: /s/ Ansbert Gadicke
                                         ---------------------------------------
                                      Name: Ansbert Gadicke
                                           -------------------------------------
                                      Title: Series A Member
                                            ------------------------------------


                                      MPM BIOVENTURES III PARALLEL FUND, L.P.

                                      By:    MPM BioVentures III GP, L.P., its
                                             General Partner
                                      By:    MPM BioVentures III LLC, its
                                             General Partner



                                      By: /s/ Ansbert Gadicke
                                         ---------------------------------------
                                      Name: Ansbert Gadicke
                                           -------------------------------------
                                      Title: Series A Member
                                            ------------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      MPM BIOVENTURES III GMBH & CO.
                                      BETEILIGUNGS KG

                                      By:    MPM BioVentures III GP, L.P., in
                                             its capacity as the Managing
                                             Limited Partner
                                      By:    MPM BioVentures III LLC, its
                                             General Partner



                                      By:    /s/ Ansbert Gadicke
                                         ---------------------------------------
                                      Name:  Ansbert Gadicke
                                           -------------------------------------
                                      Title: Series A Member
                                            ------------------------------------


                                      MPM ASSET MANAGEMENT INVESTORS 2005 BVIII
                                      LLC



                                      By:    /s/ Ansbert Gadicke
                                         ---------------------------------------
                                      Name:  Ansbert Gadicke
                                           -------------------------------------
                                      Title: Manager
                                            ------------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      APAX EUROPE VI -- A, L.P.

                                      By:    Apax Partners Europe Managers
                                             Limited, its Manager



                                      By:    /s/ Ian Jones
                                             -----------------------------------
                                      Name:  Ian Jones
                                             -----------------------------------
                                      Title: Director
                                             -----------------------------------



                                      By:    /s/ Adrian Beecroft
                                             -----------------------------------
                                      Name:  Adrian Beecroft
                                             -----------------------------------
                                      Title: Director
                                             -----------------------------------


                                      APAX EUROPE VI -- 1, L.P.

                                      By:    Apax Partners Europe Managers
                                             Limited, its Manager



                                      By:    /s/ Ian Jones
                                             -----------------------------------
                                      Name:  Ian Jones
                                             -----------------------------------
                                      Title: Director
                                             -----------------------------------



                                      By:    /s/ Adrian Beecroft
                                             -----------------------------------
                                      Name:  Adrian Beecroft
                                             -----------------------------------
                                      Title: Director
                                             -----------------------------------


                                       APAX WW NOMINEES LIMITED



                                      By:    /s/ Ian Jones
                                             -----------------------------------
                                      Name:  Ian Jones
                                             -----------------------------------
                                      Title: Director
                                             -----------------------------------



                                      By:    /s/ Adrian Beecroft
                                             -----------------------------------
                                      Name:  Adrian Beecroft
                                             -----------------------------------
                                      Title: Director
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      APAX EXCELSIOR VI, L.P.
                                      APAX EXCELSIOR VI-A C.V.
                                      APAX EXCELSIOR VI-B C.V.
                                      PATRICOF PRIVATE INVESTMENT CLUB III, L.P.

                                      By:    Apax Excelsior VI Partners, L.P.,
                                             their General Partner
                                      By:    Apax Managers, Inc., its General
                                             Partner



                                      By:     /s/ Jay Schoenfarber
                                             -----------------------------------
                                      Name:   Jay Schoenfarber
                                             -----------------------------------
                                      Title:  Attorney-in-Fact
                                             -----------------------------------


                                      PERSEUS-SOROS BIOPHARMACEUTICAL FUND, LP



                                      By:     /s/ Jay Schoenfarber
                                             -----------------------------------
                                      Name:   Jay Schoenfarber
                                             -----------------------------------
                                      Title:  Attorney-in-Fact
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      AIG PEP III DIRECT, L.P.

                                      By:    AIG Global Investment Corp., its
                                             investment adviser



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


                                      AIG PEP IV CO-INVESTMENT, L.P.

                                      By:    AIG PEP IV Co-Investment GP, L.P.,
                                             its general partner
                                      By:    AIG PEP IV Co-Investment GP, LLC,
                                             its general partner
                                      By:    AIG Global Investment Corp., its
                                             managing member



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


                                      AIG HORIZON PARTNERS FUND, L.P.

                                      By:    AIG Horizon Partners GP, L.P., its
                                             general partner
                                      By:    AIG Horizon Partners, LLC, its
                                             general partner
                                      By:    AIG Global Investment Corp., its
                                             general partner



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      AIG HORIZON SIDE-BY-SIDE FUND, L.P.

                                      By:    AIG Horizon SBS GP, L.P., its
                                             general partner
                                      By:    AIG Horizon Partners, LLC, its
                                             general partner
                                      By:    AIG Global Investment Corp., its
                                             managing member



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


                                      AIG CO-INVESTMENT FUND, L.P.

                                      By:    AIG Co-Investment General Partner,
                                             L.P., its general partner
                                      By:    AIG Direct Investments, LLC, its
                                             general partner
                                      By:    AIG Global Investment Corp., its
                                             managing member



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      AIG PRIVATE EQUITY (BERMUDA) LTD.



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      PREFERRED STOCKHOLDERS:

                                      JOHNSON & JOHNSON DEVELOPMENT CORPORATION



                                      By:    /s/ Stacey Davis
                                             -----------------------------------
                                      Name:  Stacey Davis
                                             -----------------------------------
                                      Title: Sr. Director Portfolio Investments
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      WARRANTHOLDERS:

                                      SILVER POINT CAPITAL FUND, LP



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


                                      SILVER POINT CAPITAL OFFSHORE FUND, LTD.



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


                                      SPCP GROUP III LLC



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------


<PAGE>


         IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 1
to the Amended and Restated Investor Rights Agreement as of the date first
written above.

                                      WARRANTHOLDERS:

                                      BLUE RIDGE INVESTMENTS, L.L.C.



                                      By:
                                             -----------------------------------
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------