<PAGE>

                                                                  EXHIBIT 4.7(D)

THE CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A CONFIDENTIAL TREATMENT REQUEST
IN ACCORDANCE WITH RULE 24B-2 OF THE SECURITIES AND EXCHANGE ACT OF 1934, AS
AMENDED. REDACTED PORTIONS OF THIS EXHIBIT ARE MARKED BY AN ***.

                          ALX SHARE PURCHASE AGREEMENT
                           (FOR THE PURCHASE OF SHARES
                          FROM ALX LIMITED PARTNERSHIP)

          THIS AGREEMENT is made as of the 18th day of November, 2005,

BETWEEN:

               ALX LIMITED PARTNERSHIP, a limited partnership formed under the
               laws of Ontario

               (the "VENDOR")

               -and-

               VERNALIS PLC, a corporation incorporated under the laws of
               England and Wales, with company number 2304992

               ("VERNALIS")

               -and-

               VERNALIS (CANADA) INC., a corporation incorporated under the laws
               of New Brunswick

               (the "PURCHASER")

RECITALS:

A.   Certain holders of warrants, conversion rights and options to acquire Class
     A Preference Shares, Class D Preference Shares and common shares (the
     "PRINCIPAL SHAREHOLDERS") in the capital of Cita Neuropharmaceuticals Inc.
     (the "CORPORATION"), the Purchaser, Vernalis and the Corporation have
     entered into a share purchase agreement substantially in the form attached
     in Schedule A (the "PRINCIPAL PURCHASE AGREEMENT") dated the date hereof
     whereby the Principal Shareholders have agreed to sell to the Purchaser all
     of their shares in the capital of the Corporation, including those issuable
     upon exercise of warrants, conversion rights, options and other rights to
     acquire shares in the capital of the Corporation, or to exchange certain
     options to acquire shares in the capital of the Corporation (both the
     shares and options being, collectively, the "PRINCIPAL SHAREHOLDERS'
     SECURITIES").

<PAGE>

B.   The Corporation and the Vendor are parties to a partnership call option
     agreement dated December 23, 2004 (the "CALL OPTION AGREEMENT") pursuant to
     which the Corporation has an option to purchase Class A limited partnership
     units of the GTTS XV Limited Partnership (the "OPTIONED UNITS") from the
     Vendor. The Corporation has delivered a written notice pursuant to the Call
     Option Agreement stating its intention to purchase the Optioned Units as of
     an effective date of January 6, 2006 (the "CALL DATE"). Under the Call
     Option Agreement, the Corporation may be required to pay a portion of the
     option price for the Optioned Units by issuing up to *** common shares in
     the capital of the Corporation to the Vendor depending on the fair market
     value of the Optioned Units, such number of shares to be determined on or
     before the Principal Date of Closing.

C.   The Purchaser and the Vendor wish to facilitate the purchase and sale of
     the common shares in the capital of the Corporation that the Corporation
     may issue pursuant to the Call Option Agreement, subject to and in
     accordance with the terms and conditions of this Agreement.

D.   The Vendor wishes to appoint The VenGrowth Advanced Life Sciences Fund Inc.
     to act as its representative with respect to certain matters with respect
     to this Agreement and related documents.

E.   The Purchaser is also entering into separate agreements with other holders
     of shares in the capital of the Corporation and holders of warrants,
     conversion rights, options or rights to acquire shares in the capital of
     the Corporation to acquire all such shares and/or rights.

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

                                    ARTICLE 1
                                 INTERPRETATION

1.1  DEFINITIONS

          In this Agreement,

     1.1.1 "AFFILIATE" has the meaning attributed to such term under the
     Business Corporations Act (Ontario);

     1.1.2 "AGREED PAIN PROJECT BUDGET" means the budget for the Pain Project
     agreed between the Corporation and the Purchaser;

     1.1.3 "AGREED PARKINSON'S PROJECT BUDGET" means the budget for the
     Parkinson's Project agreed between the Corporation and the Purchaser;

     1.1.4 "AGREEMENT" means this agreement and all schedules attached to this
     agreement, in each case as they may be amended or supplemented from time to
     time, and the expressions "HEREOF", "HEREIN", "HERETO", "HEREUNDER",
     "HEREBY" and


                                      -2-

<PAGE>

     similar expressions refer to this agreement; and unless otherwise
     indicated, references to Articles and sections are to Articles and sections
     in this agreement;

     1.1.5 "ALZHEIMER'S PROJECT" means the Business which relates to CNP1061 for
     the indication of Alzheimer's disease;

     1.1.6 "ALX PURCHASED SHARES" means the common shares, if any, in the
     capital of the Corporation issued to the Vendor pursuant to the Call Option
     Agreement;

     1.1.7 "ALX TIME OF CLOSING" means 11:00 a.m. on January 6, 2006 or such
     later time or date to which the Vendor and the Purchaser agree in writing;

     1.1.8 "BUSINESS" means the business of the Corporation of researching,
     developing and testing drug candidates related to the Pain Project, the
     Parkinson's Project and the Alzheimer's Project;

     1.1.9 "BUSINESS DAY" means any day, other than Saturday, Sunday or any
     statutory holiday in the Province of Ontario or London, England;

     1.1.10 "CANADIAN DOLLARS", "CDN. DOLLARS" or "CDN.$" means lawful currency
     of Canada;

     1.1.11 "CHARGE" means any security interest, lien, charge, pledge,
     encumbrance, mortgage, adverse claim or title retention agreement of any
     nature or kind;

     1.1.12 "CLASS 2 PREFERRED SHARES" means the Class 2 non-voting,
     retractable, redeemable, preferred shares, in registered form, of the
     Purchaser, having the share provisions set out in Schedule D and subject to
     the prior redemption right of the Class 1 non-voting, retractable,
     redeemable, preferred shares, in registered form, of the Purchaser, with a
     stated redemption price of U.S.$1.00 per share;

     1.1.13 "CLASS 3 PREFERRED SHARES" means the Class 3 non-voting,
     retractable, redeemable, preferred shares, in registered form, of the
     Purchaser, having the share provisions set out in Schedule D and subject to
     the prior redemption right of the Class 1 non-voting, retractable,
     redeemable, preferred shares, in registered form, of the Purchaser and the
     Class 2 Preferred Shares, with a stated redemption price of U.S.$1.00 per
     share and with an aggregate Redemption Price as set out in the Final
     Proceeds Schedule, plus the aggregate Redemption Price of any additional
     Class 3 Preferred Shares issued in accordance with section 2.6 and to other
     Persons in respect of Net Cash, and subject to further reduction and
     set-off in accordance with section 2.3.7 and the share provisions attached
     to the Purchaser Shares;

     1.1.14 "CLASS 4 PREFERRED SHARES" means the Class 4 non-voting,
     retractable, redeemable, preferred shares, in registered form, of the
     Purchaser, having the share provisions set out in Schedule D and subject to
     the prior redemption right of the Class 1 non-voting, retractable,
     redeemable, preferred shares, in registered form, of the Purchaser and the
     Class 2 Preferred Shares, with a stated redemption price of U.S.$1.00 per
     share;


                                      -3-

<PAGE>

     1.1.15 "CONVERSION RATE" means, in relation to the conversion of one
     Currency to another on a particular day, the rate of exchange quoted by the
     Bank of Canada as its spot rate of exchange for the conversion of the one
     Currency to the other at approximately noon (Toronto time) on such day;

     1.1.16 "CREST" means the relevant system, as defined in the UK
     Uncertificated Securities Regulations 1995 (SI 1995 No. 93/3272), as
     amended (in respect of which CRESTCo Limited is operator);

     1.1.17 "CURRENCY" means Canadian Dollars, Pounds Sterling or United States
     Dollars;

     1.1.18 "FDA" means the Food and Drug Administration of the United States of
     America;

     1.1.19 "FINAL CLOSING BALANCE SHEET" means the consolidated balance sheet
     of the Corporation and the Subsidiaries as at the Principal Date of
     Closing, and the calculation of Net Cash as at the Principal Date of
     Closing, prepared pursuant to the Principal Purchase Agreement;

     1.1.20 "FINAL PROCEEDS SCHEDULE" means the schedule setting out, as at the
     Principal Date of Closing, the allocation of Purchaser Shares, each class
     of shares in the capital of the Purchaser, options to acquire such shares,
     Redemption Amounts based on the occurrence of Milestones and the other
     amounts set forth therein (subject to the number of common shares issuable
     pursuant to the Call Option Agreement and prior to reduction and set-off in
     accordance with section 2.3.7 and excluding the allocation of the
     Redemption Amounts in respect of any additional Class 2 Preferred Shares,
     Class 3 Preferred Shares and Class 4 Preferred Shares issued in accordance
     with section 2.6 or to other Persons in respect of Net Cash), a pro forma
     of which is set out in Schedule B (the "PRO FORMA PROCEEDS SCHEDULE"), such
     schedule in final form to be agreed between Vernalis and the Corporation
     pursuant to the Principal Purchase Agreement;

     1.1.21 "INTERIM EXPENDITURE" has the meaning attributed to such term in the
     Principal Purchase Agreement;

     1.1.22 "MILESTONE", in respect of the Purchaser Shares, has the meaning
     attributed to such term in section 2.3.2;

     1.1.23 "MILESTONE CONSIDERATION" means the issue of Class 3 Preferred
     Shares to the Vendor as set out in the Final Proceeds Schedule and in
     accordance with section 2.3.1;

     1.1.24 "MILESTONE SHARE PRICE" means, in respect of any Vernalis Shares to
     be issued on a Redemption Date, the average of the closing middle market
     prices of a Vernalis Share as shown in the Daily Official List of the
     London Stock Exchange plc on the 30 trading days up to and including the
     trading day (the "FINAL TRADING DAY")


                                      -4-

<PAGE>

     immediately prior to the occurrence of the relevant Milestone and converted
     to the relevant Currency at the Conversion Rate on the Final Trading Day;

     1.1.25 "MILESTONE SHARES" means, in respect of any Redemption Amount, such
     number of Vernalis Shares, if any, to be allotted and issued to satisfy
     such Redemption Amount in accordance with section 2.3.5;

     1.1.26 "NET CASH" has the meaning attributed thereto in, and shall be
     determined in accordance with, the Principal Purchase Agreement;

     1.1.27 "PAIN PROJECT" means the Business which relates to CNP3381 for the
     indication of diabetic neuropathic pain;

     1.1.28 "PARKINSON'S PROJECT" means the Business which relates to CNP1512
     for the indication of Parkinson's disease;

     1.1.29 "PERSON" means any individual, partnership, limited partnership,
     joint venture, syndicate, sole proprietorship, company or corporation with
     or without share capital, unincorporated association, trust, trustee,
     executor, administrator or other legal personal representative, regulatory
     body or agency, government or governmental agency, authority or entity
     however designated or constituted;

     1.1.30 "POUNDS STERLING" or "L" means lawful currency of the United
     Kingdom;

     1.1.31 "PRINCIPAL DATE OF CLOSING" means such date for completion of the
     purchase of the Principal Shareholders' Securities pursuant to the
     Principal Purchase Agreement as determined pursuant to the Principal
     Purchase Agreement;

     1.1.32 "PRO FORMA PROCEEDS SCHEDULE" has the meaning attributed to such
     term in section 1.1.20;

     1.1.33 "PURCHASE PRICE" has the meaning attributed to such term in section
     2.2;

     1.1.34 "PURCHASER SHAREHOLDERS AGREEMENT" means the unanimous shareholders
     agreement to be entered into pursuant to the Business Corporations Act (New
     Brunswick) among all of the shareholders of the Purchaser, the Purchaser
     and Vernalis, substantially in the form attached as Schedule C;

     1.1.35 "PURCHASER SHARES" means the Class 3 Preferred Shares to be issued
     to the Vendor, if applicable, the Principal Shareholders and the other
     holders of the common shares and rights to acquire common shares in the
     capital of the Corporation, with share rights, privileges, restrictions and
     conditions set out in the share provisions substantially in the form
     attached as Schedule D;

     1.1.36 "REDEMPTION AMOUNT" means, in respect of any Redemption Date, the
     aggregate Redemption Price payable in cash and/or Vernalis Shares owing to
     the Vendor by the Purchaser upon the retraction or redemption of its
     Purchaser Shares in accordance with the share provisions attached to the
     Purchaser Shares, or by Vernalis


                                      -5-

<PAGE>

     (or its designee or assignee) upon exercise of its call right in accordance
     with section 2.3.4, and, subject in either case, to reduction or set-off of
     the Vendor's entitlement thereto in accordance with section 2.3.7 and the
     share provisions attached to the Purchaser Shares;

     1.1.37 "REDEMPTION DATE" means, in respect of any Milestone, the 45th day
     after the occurrence of that Milestone, or such other date as may be agreed
     between the Purchaser and the Vendors' Representative;

     1.1.38 "REDEMPTION PRICE" means the stated redemption price of each
     Purchaser Share in respect of a Redemption Date of U.S.$*** each;

     1.1.39 "REPORT" means the customary final report produced for filing with
     the FDA;

     1.1.40 "SPECIAL REDEMPTION DATE" has the meaning attributed to such term in
     section 2.5;

     1.1.41 "SUBSIDIARIES" means 2037137 Ontario Inc. and 2060347 Ontario Inc.,
     each incorporated under the laws of the Province of Ontario and each a
     wholly owned subsidiary of the Corporation;

     1.1.42 "UNITED STATES DOLLARS", "U.S. DOLLARS" or "U.S.$" means lawful
     currency of the United States of America;

     1.1.43 "VALUATOR" means Mr. Ezra Lwowski, or such other Person as proposed
     by the Corporation and acceptable to the Vendor to value the Optioned Units
     on or before the Principal Date of Closing;

     1.1.44 "VENDORS' REPRESENTATIVE" has the meaning attributed to such term in
     section 2.4;

     1.1.45 "VENDORS' REPRESENTATIVE AGREEMENT" has the meaning attributed to
     such term in section 2.4; and

     1.1.46 "VERNALIS SHARES" means the ordinary shares of L0.05 each in the
     capital of Vernalis, adjusted for any stock split or consolidation effected
     after the date of this Agreement.

1.2  HEADINGS

          The inclusion of headings in this Agreement is for convenience of
reference only and shall not affect the construction or interpretation hereof.

1.3  GENDER AND NUMBER

          In this Agreement, unless the context otherwise requires, words
importing the singular include the plural and vice versa, words importing gender
include all genders or the neuter, and words importing the neuter include all
genders.


                                      -6-

<PAGE>

1.4  CURRENCY CONVERSION AND INDEMNITY

          If, in connection with any action or proceeding brought in connection
with this Agreement or any judgment or order obtained as a result thereof, it
becomes necessary to convert any amount due hereunder in one Currency (the
"OTHER CURRENCY") into Canadian Dollars, then the conversion shall be made at
the Conversion Rate on the first Business Day prior to the day on which payment
is received.

          If the conversion is not able to be made in the manner contemplated by
the preceding paragraph in the jurisdiction in which the action or proceeding is
brought, then the conversion shall be made at the Conversion Rate on the date
fixed by the court for such conversion.

          If the Conversion Rate on the date of payment is different from the
Conversion Rate on such first Business Day or on the date fixed for conversion
by the court, as the case may be, the party liable to make the payment (the
"PAYOR") shall pay such additional amount (if any) in Canadian Dollars as may be
necessary to ensure that the amount paid on such payment date is the aggregate
amount in Canadian Dollars which, when converted at the Conversion Rate on the
date of payment, is the amount due in the Other Currency, together with all
costs, charges and expenses of conversion. Any additional amount owing by the
payor to the party or parties entitled to payment thereof pursuant to the
provisions of this section 1.4 shall be due as a separate debt and shall give
rise to a separate cause of action and shall not be affected by or merge into
any judgment obtained for any other amounts due under or in respect of this
Agreement.

1.5  ENTIRE AGREEMENT

          This Agreement constitutes the entire agreement between the parties
pertaining to the purchase of the common shares in the capital of the
Corporation. This Agreement supersedes all prior arrangements and
understandings, whether written or oral, relating to such subject matter in any
way. There are no warranties, conditions, or representations (including any that
may be implied by statute) and there are no agreements in connection with such
subject matter except as specifically set forth or referred to in this
Agreement. No reliance is placed on any warranty, representation, opinion,
advice or assertion of fact made either prior to, contemporaneous with, or after
entering into this Agreement, or any amendment or supplement thereto, by any
party to this Agreement or its directors, officers, employees or agents, to any
other party to this Agreement or its directors, officers, employees or agents,
except to the extent that the same has been reduced to writing and included as a
term of this Agreement, and none of the parties to this Agreement has been
induced to enter into this Agreement or any amendment or supplement by reason of
any such warranty, representation, opinion, advice or assertion of fact.
Accordingly, there shall be no liability, either in tort or in contract,
assessed in relation to any such warranty, representation, opinion, advice or
assertion of fact, except to the extent contemplated above. To the extent that
there is any inconsistency between the share provisions attached to the
Purchaser Shares and the terms of this Agreement, the terms of this Agreement
shall prevail.


                                      -7-

<PAGE>

1.6  WAIVER, AMENDMENT

          Except as expressly provided in this Agreement, no amendment or waiver
of this Agreement shall be binding unless executed in writing by the party to be
bound thereby. No waiver of any provision of this Agreement shall constitute a
waiver of any other provision nor shall any waiver of any provision of this
Agreement constitute a continuing waiver unless otherwise expressly provided.

1.7  GOVERNING LAW

          This Agreement shall be governed by and construed in accordance with
the laws of the Province of Ontario and the laws of Canada applicable therein.

1.8  ATTORNMENT

          The Vendor, Vernalis, and the Purchaser (collectively, the "ATTORNING
PARTIES" and, individually, an "ATTORNING PARTY") each agrees that any suit,
action or proceeding arising out of or relating to this Agreement against an
attorning party or any of an attorning party's assets may be brought in any
court in the Province of Ontario, and the attorning parties hereby irrevocably
and unconditionally attorn and submit to the jurisdiction of such courts. The
attorning parties irrevocably waive and agree not to raise any objection any of
them might now or hereafter have to the bringing of any such suit, action or
proceeding in any such court including, without limitation, any objection that
the place where such court is located is an inconvenient forum or that there is
any other suit, action or proceeding in any other place relating in whole or in
part to the same subject matter. Each attorning party agrees that any judgment
or order against that attorning party in any such suit, action or proceeding
brought in such a court shall be conclusive and binding upon that attorning
party and consents to any such judgment or order being recognized and enforced
in the courts of its jurisdiction of incorporation.

                                    ARTICLE 2
                                PURCHASE AND SALE

2.1  AGREEMENT TO PURCHASE AND SELL

     2.1.1 Subject to the completion of the purchase from the Principal
     Shareholders of the Principal Shareholders' Securities pursuant to the
     Principal Purchase Agreement on or before the Principal Date of Closing, to
     the issuance of the ALX Purchased Shares to the Vendor on or before the ALX
     Time of Closing by the Corporation, and to the terms of this Agreement, the
     Vendor shall sell and the Purchaser shall purchase the ALX Purchased Shares
     at the ALX Time of Closing.

     2.1.2 If the Vendor is not issued the ALX Purchased Shares on or before the
     ALX Time of Closing, none of the provisions of this Agreement will apply to
     ALX Limited Partnership and it will not be and be deemed not to be the
     Vendor under this Agreement.


                                      -8-

<PAGE>

     2.1.3 The Vendor and the Purchaser shall jointly elect under section 85 of
     the Income Tax Act (Canada) in order to transfer the ALX Purchased Shares
     to the Purchaser on a tax deferred basis, provided that the transfer meets
     the conditions of the rollover thereunder.

2.2  PURCHASE PRICE

          The purchase price (the "PURCHASE PRICE") to be paid by the Purchaser
to the Vendor for the ALX Purchased Shares shall be equal to the Milestone
Consideration, subject to adjustment on the Special Redemption Date in
accordance with section 2.5.

2.3  SATISFACTION OF MILESTONE CONSIDERATION

     2.3.1 The Milestone Consideration shall be satisfied at the ALX Time of
     Closing by the issue of such number of Class 3 Preferred Shares as is set
     out opposite the Vendor's name in the Final Proceeds Schedule, credited as
     paid in full, and delivered by the Purchaser to the Vendor in certificated
     form. The Purchaser Shares shall be redeemed by the Purchaser (and
     delivered by the Vendor to the Purchaser for redemption) on each Redemption
     Date for the applicable Redemption Amount in accordance with the share
     provisions attached to the Purchaser Shares and the provisions of this
     Agreement or, if Vernalis exercises its call right in accordance with
     section 2.3.4, purchased by Vernalis (and delivered by the Vendor to
     Vernalis for purchase) on such Redemption Date for the applicable
     Redemption Amount in accordance with the share provisions attached to the
     Purchaser Shares and the provisions of this Agreement. Each of the Vendor,
     the Purchaser and Vernalis agrees to be bound by the share provisions
     attached to the Purchaser Shares, subject to the terms of this Agreement.

     2.3.2 The occurrence of each of the following events (each a "MILESTONE")
     shall give rise to a retraction, redemption or call right in respect of the
     Purchaser Shares up to the amounts specified below (each a "MILESTONE
     PAYMENT"), in accordance with the share provisions attached to the
     Purchaser Shares and the provisions of this Agreement, and Vernalis shall
     notify the Vendors' Representative of the occurrence of each Milestone
     within 10 Business Days of its occurrence and shall indicate the Redemption
     Date with respect to such Milestone:

          2.3.2.1 in respect of the Pain Project:

               2.3.2.1.1 U.S.$5,833,334, upon the completion of a report by
               Vernalis or its affiliates to be produced in a timely manner
               following completion of a clinical study which generates data
               sufficient to support the requirements of 21 CFR 312.21(b)
               sufficient to justify Vernalis progressing with a Phase IIb or a
               Phase III study programme, as the case may be;

               2.3.2.1.2 U.S.$5,833,333, upon the completion of a Report by
               Vernalis or its affiliates to be provided in a timely manner
               following completion of a clinical study which generates data
               sufficient to support the requirements of 21 CFR 312.21(c) for a
               submission for regulatory approval to the FDA


                                      -9-

<PAGE>

               to market and sell in the USA a product comprising CNP3381 for
               the treatment of diabetic neuropathic pain; and

               2.3.2.1.3 U.S.$5,833,333, upon the issuance by the FDA of a
               written notification to Vernalis or its affiliates pursuant to 21
               CFR 314.105(a) that the FDA approves CNP3381 for the treatment of
               diabetic neuropathic pain, Alzheimer's disease, post-operative
               pain or mixed pain related to palliative care. For greater
               certainty, if CNP3381 is developed for more than one of the
               above-noted indications, only the first FDA approval for one of
               the indications noted above shall be a Milestone. If the
               Milestone referred to in section 2.3.2.1.2 has not occurred prior
               to the FDA approval contemplated by this section 2.3.2.1.3, that
               Milestone shall be deemed to occur concurrently with the
               occurrence of the Milestone contemplated in this section
               2.3.2.1.3; and

          2.3.2.2 in respect of the Parkinson's Project:

               2.3.2.2.1 U.S.$5,833,334, upon the enrollment by Vernalis or its
               affiliates of the first patient into a Phase III study for the
               purpose of generating data to support the requirements of 21 CFR
               312.21(b);

               2.3.2.2.2 U.S.$5,833,333, upon the completion of a Report by
               Vernalis or its affiliates to be produced in a timely manner
               following completion of a trial which generates data sufficient
               to support the requirements of 21 CFR 312.21(c) for a submission
               for regulatory approval to the FDA to market and sell in the USA
               a product comprising CNP1512 for the treatment of Parkinson's
               disease; and

               2.3.2.2.3 U.S.$5,833,333, upon the issuance by the FDA of a
               written notification to Vernalis or its affiliates pursuant to 21
               CFR 314.105(a) that the FDA approves CNP1512 for the treatment of
               Parkinson's disease,

          provided that the Milestone Payment in respect of each of the first
          two Milestones to occur shall be reduced by an amount equal to
          one-half of the amount of the Interim Expenditure.

          2.3.3 Subject to section 2.3.4, the Redemption Amount in respect of a
          Redemption Date shall be satisfied by the allotment and issue of
          Vernalis Shares or, at the option of the Purchaser, by payment in cash
          or by a combination of cash and Vernalis Shares (such combination of
          cash and Vernalis Shares to be at the discretion of the Purchaser) on
          that Redemption Date. Notwithstanding the foregoing, the Redemption
          Amount in respect of the Special Redemption Date, if applicable, may
          only be satisfied in cash.

          2.3.4 Vernalis (or its designee or assignee) may, at its option,
          elect, by notice to the Vendors' Representative at any time after the
          occurrence of a Milestone and on or before the relevant Redemption
          Date, to purchase, on the relevant Redemption Date, such Purchaser
          Shares which may be redeemed on such Redemption Date for the
          applicable Redemption Amount, notwithstanding that the Vendor or the
          Purchaser has


                                      -10-

<PAGE>

          exercised its retraction or redemption right, respectively, pursuant
          to the share provisions attached to the Purchaser Shares. If Vernalis
          exercises its call right in accordance with this section 2.3.4 and the
          share provisions attached to the Purchaser Shares in respect of a
          Redemption Date, the Redemption Amount payable on that Redemption Date
          shall be satisfied by the allotment and issue of Vernalis Shares or,
          at the option of Vernalis, by payment in cash or by a combination of
          cash and Vernalis Shares (such combination of cash and Vernalis Shares
          to be at the discretion of Vernalis) on that Redemption Date and in
          accordance with the share provisions attached to the Purchaser Shares.
          Upon exercise by Vernalis of its call right in accordance with this
          section 2.3.4, the retraction and redemption right of the Vendor or
          the Purchaser pursuant to the share provisions attached to the
          Purchaser Shares in respect of the Redemption Date shall be cancelled.
          Notwithstanding the foregoing, the Redemption in respect of the
          Special Redemption Date, if applicable, may only be satisfied in cash.

          2.3.5 To the extent the Purchaser or Vernalis, as applicable, elects
          not to satisfy any Redemption Amount in cash, Vernalis shall allot and
          issue Vernalis Shares, credited as paid in full, and deliver on the
          relevant Redemption Date to the Vendor (or its nominee), in
          uncertificated form to an account in CREST designated by the Vendor,
          such number of Vernalis Shares as at the Milestone Share Price shall
          be equal to the Vendor's entitlement to a Redemption Amount divided by
          the Milestone Share Price (rounded up to the nearest whole share),
          subject to any further reduction as provided in section 2.3.7.

          2.3.6 Any Redemption Amount to be satisfied in cash, subject to any
          further reduction as provided in section 2.3.7, shall be paid on the
          relevant Redemption Date to the Vendors' Representative, on behalf of
          the Vendor, and the Vendors' Representative shall pay such Redemption
          Amount to the Vendor in accordance with its entitlement on the
          Redemption Date and neither the Purchaser nor Vernalis, as applicable,
          shall have any responsibility for such distribution. The Vendors'
          Representative may, not less than five Business Days prior to the
          relevant Redemption Date, direct the Purchaser or Vernalis, as
          applicable, to pay to the Vendor directly any amounts contemplated by
          this section 2.3.6.

          2.3.7 The Vendor's entitlement to a Redemption Amount on a Redemption
          Date may be further reduced and set-off by the Purchaser or Vernalis
          by and against the amount of any claim against the Vendor in respect
          of any loss, damages or deficiencies suffered by the Purchaser or
          Vernalis as a result of any breach by the Vendor of a representation
          or covenant contained in this Agreement, being either the approximate
          and reasonable estimate of the likely amount of any such claim as
          determined by the Purchaser or Vernalis, as applicable, or, if such
          claim has been settled or finally determined, the amount of such
          claim, to the extent not satisfied in full on the fifth Business Day
          preceding the Redemption Date (using the Milestone Share Price as the
          value of the Milestone Shares when calculating the number of Milestone
          Shares to be reduced).


                                      -11-

<PAGE>

          2.3.8 In the event the Vendor's entitlement to a Redemption Amount is
          reduced by the amount of an estimated claim (the "ESTIMATED CLAIM") as
          provided in section 2.3.7, upon such claim becoming settled or finally
          determined (the "DETERMINED CLAIM"), the Purchaser or Vernalis, as
          applicable, shall, if and to the extent the amount of the Determined
          Claim for which the Vendor is responsible is less than the Estimated
          Claim for which the Vendor is responsible, satisfy the difference (up
          to the amount of the reduction made pursuant to section 2.3.7) in cash
          or Vernalis Shares or a combination of the two (depending upon and
          proportionately to whether the relevant Redemption Amount was
          satisfied in cash or Vernalis Shares or a combination of the two) and
          the provisions of this section 2.3 shall apply mutatis mutandis, with
          the Milestone Share Price, when calculating the number of Vernalis
          Shares to be issued pursuant to this section 2.3.8, being that used in
          respect of the relevant Redemption Date.

          2.3.9 Notwithstanding that the Purchaser or Vernalis, as applicable,
          elects to pay a Redemption Amount, in whole or in part, in Vernalis
          Shares, the Purchaser or Vernalis, as applicable, may elect to pay to
          any Person who is located or resident in a jurisdiction on the
          Redemption Date, or date for payment pursuant to section 2.3.8, where
          the issuance of such shares would be in contravention of applicable
          securities laws (with no obligation to qualify or register the shares
          or rely upon an exemption from such requirement), its entitlement to a
          Redemption Amount in cash only.

          2.3.10 In the event that any partner of the Vendor is a non-resident
          of Canada under the Income Tax Act (Canada) on any Redemption Date, or
          date for payment pursuant to section 2.3.8, it shall deliver to the
          Purchaser or Vernalis, as applicable, a certificate issued pursuant to
          section 116 of the Income Tax Act (Canada) on account of the Vendor's
          entitlement to a Redemption Amount on such Redemption Date, or date
          for payment pursuant to section 2.3.8. Notwithstanding the foregoing,
          neither the Purchaser nor Vernalis, as applicable, shall be required
          to issue any Purchaser Shares or Vernalis Shares to the Vendor until
          the delivery of such certificate, as applicable. The Purchaser or
          Vernalis, as applicable, shall be entitled to deduct or withhold from
          any Redemption Amount payable to the Vendor any amount required to be
          deducted or withheld under applicable law.

          2.3.11 Vernalis (or its designee or assignee) may, at its option,
          elect by notice to the Vendors' Representative at any time after the
          earlier of (i) the tenth anniversary of the Principal Date of Closing
          or (ii) the Redemption Date in respect of the last Milestone to occur,
          provided that any Redemption Amount owing in respect of such
          Redemption Date has been satisfied in full, to purchase, on the date
          specified in such notice, all of the outstanding Purchaser Shares for
          a purchase price of U.S. $*** per share, payable in cash to the
          Vendors' Representative on behalf of the Vendor.

2.4  APPOINTMENT OF VENDORS' REPRESENTATIVE

          The Vendor hereby appoints The VenGrowth Advanced Life Sciences Fund
Inc. to act as its representative (the "VENDORS' REPRESENTATIVE") to carry out
such duties and responsibilities and to exercise such rights and powers on its
behalf as are provided in this


                                      -12-

<PAGE>

Agreement and in related documents in accordance with an agreement (the
"VENDORS' REPRESENTATIVE AGREEMENT") to be entered into among the Vendors'
Representative, the Vendor, and certain other Persons to become shareholders or
optionholders of the Purchaser (other than Vernalis).

          In the event of any disagreement between the Vendor and/or the
Vendors' Representative resulting in adverse claims or demands with respect to
the amounts delivered under this Agreement to the Vendors' Representative on
behalf of the Vendor, the Vendors' Representative shall be entitled, at its
option, to refuse to comply with any claims or demands on it with respect
thereto so long as such disagreement shall continue, and in so refusing, the
Vendors' Representative may elect to make no delivery of such amounts. In doing
so, the Vendors' Representative shall not be or become liable in any way to the
Vendor, Vernalis or the Purchaser for its failure or refusal to comply with such
claims or demands.

          The Vendors' Representative may resign from such position at any time
by written notice to the parties to the Vendors' Representative Agreement, the
Purchaser and Vernalis provided that the Vendors' Representative shall have
appointed a successor to the Vendors' Representative satisfactory to the
Purchaser, acting reasonably, which appointment will be binding on the parties
to the Vendors' Representative Agreement, and provided that such successor shall
have consented to act in such capacity.

2.5  DELIVERY OF SHARE CERTIFICATES

          At the ALX Time of Closing, subject to having received the same from
the Corporation, the Vendor shall deliver to the Purchaser share certificates
representing the ALX Purchased Shares duly endorsed in blank for transfer or
accompanied by duly signed powers of attorney for transfer in blank.

2.6  NET CASH PAYMENT

          On the 15th Business Day after the final determination of the Final
Closing Balance Sheet in accordance with the Principal Purchase Agreement, if
the Net Cash as set out in the Final Closing Balance Sheet is a positive number,
the Purchaser shall issue to the Vendor on such date (the "SPECIAL REDEMPTION
DATE") such number of Class 3 Preferred Shares (rounded upwards to the nearest
whole share) with an aggregate Redemption Price equal to the amount of such Net
Cash, converted to U.S. Dollars at the Conversion Rate as at the Principal Date
of Closing, multiplied by a fraction, (i) the numerator of which is the
aggregate of the number of Class 3 Preferred Shares owned by the Vendor on the
Special Redemption Date and (ii) the denominator of which is the aggregate of
all Class 3 Preferred Shares outstanding on the Special Redemption Date and of
all Class 4 Preferred Shares issuable upon exercise of all options outstanding
on the Special Redemption Date. Such Class 3 Preferred Shares issuable to the
Vendor shall be credited as paid in full, and delivered by the Purchaser to the
Vendors' Representative, on behalf of the Vendor, in certificated form.

2.7  FINAL PROCEEDS SCHEDULE

          The Final Proceeds Schedule shall be based on the Pro Forma Proceeds
Schedule and calculated in accordance with, and in a manner consistent with, the
spreadsheet contained


                                      -13-

<PAGE>

within the CD-Rom delivered by the Corporation to Vernalis on the date of this
Agreement, updated to reflect the final resolution as at the Principal Date of
Closing of the variable factors noted in the Pro Forma Proceeds Schedule (other
than those variables to be reflected in the Final Closing Balance Sheet). The
Final Proceeds Schedule as agreed between Vernalis and the Corporation shall be
binding upon the parties to this Agreement, and neither the Purchaser nor
Vernalis shall have any responsibility or liability for any dispute or claim
arising as to the allocation, in accordance with the Final Proceeds Schedule, of
Purchaser Shares, each class of shares in the capital of the Purchaser, options
to acquire such shares, Redemption Amounts and the other amounts set forth
therein. The Vendor acknowledges and agrees that the Pro Forma Proceeds Schedule
and the Final Proceeds Schedule are intended only to set out the allocation of
Purchaser Shares, each class of shares in the capital of the Purchaser, options
to acquire such shares, Redemption Amounts and the other amounts set forth
therein (prior to reduction and set-off in accordance with section 2.3.7 and
excluding the issue of any additional Class 2 Preferred Shares, Class 3
Preferred Shares and Class 4 Preferred Shares pursuant to section 2.6 or to
other Persons in respect of Net Cash), and, subject to section 2.6, nothing in
this section 2.7 shall oblige the Purchaser or Vernalis to pay, issue or allot
(or procure the payment, issue or allotment of) additional consideration to the
Vendor. In the event that additional Class 2 Preferred Shares, Class 3 Preferred
Shares or Class 4 Preferred Shares are issued pursuant to section 2.6 or to
other Persons in respect of Net Cash, the Final Proceeds Schedule shall be
updated by the Purchaser and the Vendors' Representative accordingly.

                                    ARTICLE 3
                         REPRESENTATIONS AND WARRANTIES

3.1  VENDOR'S REPRESENTATIONS AND WARRANTIES

          The Vendor hereby represents and warrants to each of the Purchaser and
Vernalis as follows and the Vendor acknowledges that each of the Purchaser and
Vernalis is relying upon the following representations and warranties in
connection with the purchase of the ALX Purchased Shares (and such
representations and warranties shall be deemed to be repeated at the Principal
Date of Closing and, in the case of the representation and warranty contained in
section 3.1.10, unless the Purchaser and Vernalis have been notified otherwise
in writing at least 10 Business Days prior thereto, on each Redemption Date or
date of payment under section 2.3.8):

     3.1.1 FORMATION. It is a limited partnership duly formed, organized and
     subsisting under the laws of Ontario.

     3.1.2 CAPACITY AND DUE AUTHORIZATION. It has the corporate power and
     capacity to enter into, and to perform its obligations under, this
     Agreement.

     3.1.3 ENFORCEABILITY. This Agreement has been duly authorized, executed and
     delivered by it and is its valid and binding obligation, enforceable
     against it in accordance with its terms, subject to the usual exceptions as
     to bankruptcy and the availability of equitable remedies.

     3.1.4 TITLE TO, AND RIGHT TO, SELL ALX PURCHASED SHARES. There are no
     agreements or restrictions which in any way limit or restrict the transfer
     to the


                                      -14-

<PAGE>

     Purchaser of the ALX Purchased Shares nor are there any shareholders
     agreements, pooling agreements, voting trusts or other agreements or
     understandings with respect to the voting of the ALX Purchased Shares. At
     the ALX Time of Closing, subject to any restriction or Charge imposed by
     the Corporation's articles, by-laws or any agreement to which the
     Corporation is a party (and to which the Vendor is not a party or has not
     agreed to be bound thereby), it will be the sole registered and beneficial
     owner of the ALX Purchased Shares with good and marketable title thereto,
     free of all Charges and it will have full legal right, power and authority
     to sell the ALX Purchased Shares to the Purchaser.

     3.1.5 AMOUNTS OWING BY THE CORPORATION. At the ALX Time of Closing, there
     shall be no liabilities, indemnities or amounts owing to the Vendor by the
     Corporation or the Subsidiaries (other than the valid issuance by the
     Corporation of the ALX Purchased Shares to the Vendor as fully paid in
     accordance with the Call Option Agreement).

     3.1.6 NO CONTRAVENTION. None of the entering into of this Agreement nor the
     performance by it of any of its obligations under this Agreement will
     contravene, breach or result in any default under its articles, by-laws,
     constating documents or other organizational documents, if applicable, or
     under any mortgage, lease, agreement, other legally binding instrument,
     licence, permit, statute, regulation, order, judgment, decree or law to
     which it is a party or by which it may be bound.

     3.1.7 CONSENTS AND APPROVALS. No authorization, consent or approval of, or
     filing with or notice to, any governmental agency, regulatory body, court
     or other Person is required in connection with the execution, delivery or
     performance by it of this Agreement or the sale by it of any of the ALX
     Purchased Shares hereunder.

     3.1.8 COMPLIANCE WITH CONFIDENTIALITY OBLIGATIONS. It has complied with all
     applicable confidentiality or proprietary obligations in favour of the
     Corporation and has not, directly of indirectly, used for its own purposes
     or disclosed to any Person any confidential or proprietary information of
     the Corporation or its Subsidiaries, including know-how and data, technical
     or non-technical, relating to the Business.

     3.1.9 TAX RESIDENCY. It is a Canadian partnership under the Income Tax Act
     (Canada).

     3.1.10 U.S. SECURITIES LAWS. It is not located or resident in the United
     States of America for securities laws purposes.

3.2  PURCHASER'S AND VERNALIS' REPRESENTATIONS AND WARRANTIES

          The Purchaser and Vernalis each jointly and severally represents and
warrants to the Vendor as follows and acknowledges that the Vendor is relying
upon the following representations and warranties in connection with its sale of
the ALX Purchased Shares (and such representations and warranties shall be
deemed to be repeated at the Principal Date of Closing):


                                      -15-

<PAGE>

     3.2.1 INCORPORATION. The Purchaser is duly incorporated and validly
     existing under the laws of New Brunswick. Vernalis is duly incorporated and
     validly existing under the laws of England and Wales.

     3.2.2 CORPORATE POWER AND DUE AUTHORIZATION. The Purchaser and Vernalis
     each have the corporate power and capacity to enter into, and to perform
     its obligations under, this Agreement, subject to shareholder and
     regulatory approvals and requirements and filings in connection with the
     issue of securities of the Purchaser and Vernalis as contemplated herein.
     This Agreement has been duly authorized by the board of directors of each
     of the Purchaser and Vernalis. This Agreement has been duly executed and
     delivered by the Purchaser and Vernalis.

     3.2.3 ENFORCEABILITY. This Agreement is a valid and binding obligation of
     each of the Purchaser and Vernalis, enforceable in accordance with its
     terms, subject to the usual exceptions as to bankruptcy and the
     availability of equitable remedies.

     3.2.4 NO CONTRAVENTION. None of the entering into of this Agreement nor the
     performance by the Purchaser nor Vernalis of any of its obligations under
     this Agreement will contravene, breach or result in any default under its
     articles, by-laws, constating documents or other organizational documents
     or under any mortgage, lease, agreement, other legally binding instrument,
     licence, permit, statute, regulation, order, judgment, decree or law to
     which it is a party or by which it may be bound.

     3.2.5 CONSENTS AND APPROVALS. No authorization, consent or approval of, or
     filing with or notice to, any governmental agency, regulatory body, court
     or other Person is required in connection with the execution, delivery or
     performance by the Purchaser nor Vernalis of this Agreement nor the
     performance by it of any of its obligations, subject to shareholder and
     regulatory approvals and requirements and filings in connection with the
     issue of securities of the Purchaser and Vernalis as contemplated herein.

     3.2.6 ISSUE OF PURCHASER SHARES AND VERNALIS SHARES. At the time of issue
     of the Purchaser Shares or Vernalis Shares in accordance with the share
     provisions attached to the Purchaser Shares and the provisions of this
     Agreement, such Purchaser Shares and Vernalis Shares, as the case may be,
     shall be validly issued and fully paid and such Vernalis Shares will be
     listed for trading on a recognized stock exchange.

                                    ARTICLE 4
                                    COVENANTS

4.1  VENDOR'S COVENANTS

          The Vendor covenants in favour of the Purchaser and Vernalis as
follows:

     4.1.1 PURCHASER SHAREHOLDERS AGREEMENT. To enter into, at the ALX Time of
     Closing, the Purchaser Shareholders Agreement and hereby authorizes the
     Vendors' Representative to execute the Purchaser Shareholders Agreement on
     its behalf.


                                      -16-
<PAGE>

     4.1.2 VENDORS' REPRESENTATIVE AGREEMENT. To enter into, at the ALX Time of
     Closing, the Vendors' Representative Agreement.

     4.1.3 WITHDRAWAL RIGHT. To not exercise, or attempt to exercise, any
     statutory right or entitlement to withdraw which may be applicable to, or
     enforceable by, it under United Kingdom securities laws relating to the
     issue of Vernalis Shares to it under this Agreement. The Vendor
     acknowledges that the issue of Vernalis Shares to it under this Agreement
     will not entitle it to withdraw in the event that Vernalis publishes a
     supplementary prospectus. The Vendor further covenants in favour of
     Vernalis that, in the event it is so entitled to withdraw, by signing this
     Agreement, it is confirming its acceptance of the offer of Vernalis Shares
     contained in this Agreement on the same terms immediately after such
     withdrawal.

                                   ARTICLE 5
                                 GENERAL MATTERS

5.1  CONFIDENTIALITY

     5.1.1 The Vendor shall not directly or indirectly use for its own purposes
     or disclose to any other Person any confidential or proprietary
     information, including know-how and data, technical or non-technical,
     relating to the business of Vernalis which becomes known to the Vendor or
     its accountants, legal advisers or representatives as a result of Vernalis
     making the same available in connection with the transaction contemplated
     hereby.

     5.1.2 The Vendor shall not directly or indirectly use for its own purposes
     or disclose to any Person any confidential or proprietary information of
     the Corporation or the Subsidiaries, including know-how and data, technical
     or non-technical, relating to the Business.

5.2  PUBLIC NOTICES

          No press release or other public announcement concerning the
transaction contemplated by this Agreement shall be made by the Vendor without
the prior written consent of Vernalis.

5.3  EXPENSES

          Each of the Vendor, the Purchaser and Vernalis shall be responsible
for the expenses (including fees and expenses of legal advisers, accountants and
other professional advisers) incurred by it in connection with the negotiation
and settlement of this Agreement and the completion of the transactions
contemplated hereby.

5.4  TERMINATION

          This Agreement shall terminate and the obligations and covenants of
the parties hereunder, other than those set out in sections 5.1, 5.2 and 5.3
shall terminate upon the


                                      -17-

<PAGE>

termination of the Principal Purchase Agreement or in the event that the
Valuator determines that no shares are issuable to the Vendor pursuant to its
valuation of the Optioned Units, but shall not terminate prior thereto in any
circumstances.

5.5  ASSIGNMENT

          Except as provided in this section, no party may assign its rights or
benefits under this Agreement, nor may the Vendor transfer its Purchaser Shares
to any Person other than Vernalis or an affiliate of Vernalis. The Purchaser or
Vernalis may, at any time after the Principal Date of Closing and from time to
time, assign its rights and benefits under this Agreement, in whole or in part,
to any affiliate or to any Person who acquires all or substantially all of the
assets or shares of the Corporation.

5.6  NOTICES

          Any notice or other communication required or permitted to be given
hereunder shall be in writing and shall be given by prepaid mail, by facsimile
or other means of electronic communication or by hand-delivery as hereinafter
provided. Any such notice or other communication, if mailed by prepaid mail at
any time other than during a general discontinuance of postal service due to
strike, lockout or otherwise, shall be deemed to have been received on the
seventh Business Day after the post-marked date thereof, or if sent by facsimile
or other means of electronic communication, shall be deemed to have been
received on the Business Day following the sending, or if delivered by hand
shall be deemed to have been received at the time it is delivered to the
applicable address noted below either to the individual designated below or to
an individual at such address having apparent authority to accept deliveries on
behalf of the addressee. Notice of change of address shall also be governed by
this section 5.6. In the event of a general discontinuance of postal service due
to strike, lock-out or otherwise, notices or other communications shall be
delivered by hand or sent by facsimile or other means of electronic
communication and shall be deemed to have been received in accordance with this
section 5.6. Notices and other communications shall be addressed as follows:

     (a)  if to the Vendor:

          ALX Limited Partnership
          Suite 550, 141 Adelaide Street West
          Toronto, Ontario
          M5H 3L5

          Attention:         ALX GP Inc.
          Telecopier number: 416-304-0669


                                      -18-

<PAGE>

          with a copy to the Vendor's counsel at:

          Kavanagh Bateman & Baek LLP
          Suite 550, 141 Adelaide Street West
          Toronto, Ontario
          M5H 3L5

          Attention:         Peter H. Baek
          Telecopier number: 416-304-0669

          and with a copy to the Vendors' Representative at:

          The VenGrowth Advanced Life Sciences Fund Inc.
          105 Adelaide Street West, Suite 1000
          Toronto, Ontario
          M5H 1P9

          Attention:         Dr. Luc Marengere/Phil Kurtz
          Telecopier number: 416-971-6519

     (b)  if to the Purchaser or Vernalis:

          Vernalis plc
          Oakdene Court
          613 Reading Road
          Winnersh, Berkshire
          RG 41 5UA

          Attention:         John Slater
          Telecopier number: + 44 118 989 9300

          with a copy to the Purchaser's counsel at:

          Torys LLP
          Suite 3000, 79 Wellington Street West
          Box 270, TD Centre
          Toronto, Ontario M5K 1N2

          Attention:         Kathleen L. Keller-Hobson
          Telecopier number: (416) 865-7380

          and to:


                                      -19-

<PAGE>

          Allen & Overy LLP
          One New Change
          London EC4M 9QQ
          United Kingdom

          Attention:         Anna Buscall
          Telecopier number: + 44 20 7330 9999

          The failure to send or deliver a copy of a notice to the Purchaser's
Counsel or the Vendors' Counsel, as the case may be, shall not invalidate any
notice given under this section 5.6.

5.7  TIME OF ESSENCE

          Time is of the essence of this Agreement.

5.8  FURTHER ASSURANCES

          Each of the parties shall promptly do, make, execute, deliver, or
cause to be done, made, executed or delivered, all such further acts, documents
and things as the other party hereto may reasonably require from time to time
for the purpose of giving effect to this Agreement and shall use reasonable
efforts and take all such steps as may be reasonably within its power to
implement to their full extent the provisions of this Agreement.

5.9  COUNTERPARTS

          This Agreement may be signed in counterparts and each such counterpart
shall constitute an original document and such counterparts, taken together,
shall constitute one and the same instrument.


                                      -20-

<PAGE>

          IN WITNESS WHEREOF the parties hereto have executed this Agreement.

                                        ALX LIMITED PARTNERSHIP, BY ALX GP INC.
                                        IN ITS CAPACITY AS THE GENERAL PARTNER


                                        by:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        by:
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                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        VERNALIS PLC


                                        by:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        VERNALIS (CANADA) INC.


                                        by:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

          The undersigned hereby agrees to act as the Vendors' Representative
and to carry out such duties and responsibilities on behalf of the Vendor as
provided in this Agreement.

                                        THE VENGROWTH ADVANCED LIFE SCIENCES
                                        FUND INC., as Vendors' Representative


                                        by:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        by:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

                                       Signature Page for ALX Purchase Agreement