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                                                                   EXHIBIT 10.22
                             SUBSCRIPTION AGREEMENT


         THIS SUBSCRIPTION AGREEMENT (this "Agreement") is dated as of October
19, 2001, and is by and between AESGEN, INC., a Delaware corporation ("Aesgen"
or the "Company"), aaiPHARMA INCORPORATED, a Delaware corporation (the
"Purchaser").

         WHEREAS, the Purchaser and Aesgen have or will enter into an agreement
(proposal number 01-068-R2) (the "Service Agreement") pursuant to which
Purchaser agrees to perform certain services for Aesgen relating to Aesgen's
Phase III clinical trials for AES-14 (the "Services");

         WHEREAS, the Services will be performed by Purchaser over time, and,
pursuant to the Service Agreement, Aesgen will be required to pay Purchaser for
such Services;

         WHEREAS, the Purchaser wishes to purchase up to the number of shares of
Series D Convertible Preferred Stock, par value $.01 per share ("Series D
Preferred Stock"), of Aesgen as set forth on the Election Form attached hereto
as Annex A (the "Subscribed Shares") for the purchase price of $100.00 per share
of Series D Preferred Stock (the "Purchase Price");

         WHEREAS, the Purchaser has agreed to accept, and Aesgen has agreed to
issue, in lieu of cash for the Services to be performed, Series D Preferred
Stock.

         NOW, THEREFORE, in consideration of the mutual promises set forth
herein, the parties agree as follows:

         SECTION 1. COMMITMENT.

         The Purchaser hereby subscribes for and agrees to purchase the
Subscribed Shares, each at the Purchase Price.

         SECTION 2. PAYMENT OF THE PURCHASE PRICE AND DELIVERY OF THE SHARES.

                  (a) Subject to the terms and conditions hereof and on the
         basis of the representations and warranties hereinafter set forth, the
         Purchaser hereby agrees to purchase, and Aesgen agrees to issue and
         sell to the Purchaser, subject to Section 2(c) hereof, such number of
         shares of Series D Preferred Stock at the aggregate Purchase Price as
         set forth opposite such Purchaser's name on Schedule I hereto (the
         "Accepted Shares"); provided such number of shares shall be no greater
         than the Subscribed Shares.

                  (b) Pursuant to the Service Agreement the Purchaser shall
         deliver to Aesgen monthly invoices for Services rendered for the month
         then ended. Notwithstanding the provisions of the Service Agreement to
         the contrary, until the aggregate amount payable to the Purchaser under
         the Service Agreement shall exceed the aggregate Purchase Price for the
         Accepted Shares, Aesgen shall only be responsible for payment for such
         Services as set forth in Section 2(c) hereof.


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                  (c) The shares of Series D Preferred Stock to be issued
         hereunder shall be issued at the following times and in the following
         amounts:

                  (i) As soon as practicable after the interim analysis of
         Aesgen's current Phase III clinical trial for AES-14 (the "Trial") is
         available, Aesgen shall deliver to the Purchaser Series D Preferred
         Stock in an amount (the "First Installment"), the aggregate Purchase
         Price for which shall be equal to the aggregate amount of all unpaid
         and undisputed invoices delivered pursuant to the Service Agreement to
         Aesgen by the Purchaser prior to such date.

                  (ii) As soon as practicable after the earlier of (i) the
         completion or abandonment of the Trial or (ii) the aggregate amount
         invoiced under the Service Agreement shall equal or exceed the
         aggregate Purchase Price for the Accepted Shares, Aesgen will deliver
         to the Purchaser additional Series D Preferred Stock in an amount (the
         "Second Installment"), the aggregate Purchase Price for which shall
         equal all unpaid and undisputed invoices delivered pursuant to the
         Service Agreement prior to such time.

                  (iii) To the extent the amount of First Installment and the
         Second Installment combined is less than the number of the Accepted
         Shares, Aesgen shall deliver to the Purchaser shares of Series D
         Preferred Stock in an amount equal to the Accepted Shares less the
         First Installment and the Second Installment in lieu of any cash
         payments that may become due under any services or supply agreement
         entered into between Aesgen and the Purchaser.

                  (iv) Notwithstanding the foregoing, no fractional shares of
         Series D Preferred Stock shall be issued and any amount representing a
         fraction of a share shall be carried forward until the next payment
         made hereunder, and the aggregate amount of shares of Series D
         Preferred Stock issued hereunder shall not exceed the number of the
         Accepted Shares.

         SECTION 3. REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE PURCHASER.

         In order to induce Aesgen to accept this subscription and issue shares
of Series D Preferred Stock to the Purchaser, the Purchaser hereby represents
and warrants to Aesgen that:

                  (a) The execution, delivery and performance by the Purchaser
         of this Agreement and the purchase of the Subscribed Shares have been
         duly authorized by all action on the Purchaser's part.

                  (b) Purchaser understands that the Subscribed Shares to be
         purchased by him (i) will not be registered under the Securities Act of
         1933, as amended (the "Securities Act") or the securities laws of any
         state, by reason of their issuance in a transaction exempt from the
         registration or qualification requirements of the Securities Act such
         securities laws, the availability of which depends upon, among other
         things, the bona fide nature of the investment intent and the accuracy
         of such Purchaser's representations as expressed herein, and (ii) must
         be held indefinitely unless a subsequent disposition thereof is
         registered under the Securities Act or is exempt from registration.


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                  (c) This Agreement has been duly executed and delivered by the
         Purchaser and constitutes the legal, valid and binding obligation of
         the Purchaser, enforceable in accordance with its terms subject, as to
         enforcement of remedies, to general equity principles and to applicable
         bankruptcy, insolvency and similar laws and moratorium from time to
         time in effect.

                  (d) The Purchaser is acquiring the Subscribed Shares for its
         own account, for investment and without any intent to make a
         distribution thereof, and each certificate representing the Subscribed
         Shares, and any other securities issued in respect of such Subscribed
         Shares upon any stock split, stock dividend, recapitalization, merger
         or similar event, unless no longer required in the opinion of counsel
         (which opinion and counsel shall be reasonably satisfactory to Aesgen),
         shall bear a legend substantially in the following form:

                  THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
                  REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR
                  THE SECURITIES LAWS OF ANY STATE. THE SECURITIES MAY NOT BE
                  TRANSFERRED EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION
                  STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAW
                  OR UPON DELIVERY TO AESGEN OF AN OPINION OF COUNSEL
                  SATISFACTORY TO AESGEN THAT REGISTRATION UNDER THE ACT AND
                  APPLICABLE STATE SECURITIES LAW IS NOT REQUIRED.

                  AESGEN IS AUTHORIZED TO ISSUE DIFFERENT CLASSES OF STOCK AND
                  WILL FURNISH TO A STOCKHOLDER ON REQUEST AND WITHOUT CHARGE
                  INFORMATION REGARDING THE DESIGNATIONS, PREFERENCES, AND
                  RELATIVE, PARTICIPATING, OPTIONAL AND OTHER SPECIAL RIGHTS OF
                  EACH CLASS OF STOCK AND THE QUALIFICATIONS, LIMITATIONS OR
                  RESTRICTIONS OF SUCH PREFERENCES AND/OR RIGHTS.

                  THE SALE, ASSIGNMENT, HYPOTHECATION, PLEDGE, ENCUMBRANCE OR
                  OTHER DISPOSITION (EACH A "TRANSFER") AND VOTING ANY OF THE
                  SECURITIES REPRESENTED BY THIS CERTIFICATE ARE RESTRICTED BY
                  THE TERMS OF THE AMENDED AND RESTATED STOCKHOLDERS' AGREEMENT,
                  DATED AS OF JANUARY 30, 1998, AMONG AESGEN AND THE
                  STOCKHOLDERS NAMED THEREIN, A COPY OF WHICH MAY BE INSPECTED
                  AT AESGEN'S PRINCIPAL OFFICE. AESGEN WILL NOT REGISTER THE
                  TRANSFER OF SUCH SECURITIES ON THE BOOKS OF AESGEN UNLESS AND
                  UNTIL THE TRANSFER HAS BEEN MADE IN COMPLIANCE WITH THE TERMS
                  OF THE STOCKHOLDERS' AGREEMENT.

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                  (e) The Purchaser is an "accredited investor," as defined in
         Rule 501 (the provisions of which are known to the Purchaser)
         promulgated under the Securities Act.

                  (f) The Purchaser understands that no public market now exists
         for the Subscribed Shares or any other security issued in respect of
         such Subscribed Shares.

                  (g) Based on the Purchaser's knowledge, experience and skill
         in evaluating and investing in issues of securities derived from actual
         participation in financial, investment, tax and business matters, the
         Purchaser is capable of evaluating the merits and risks of an
         investment in the Subscribed Shares and the suitability of the
         Subscribed Shares as an investment for the Purchaser.

                  (h) The Purchaser acknowledges that Aesgen has incurred
         substantial losses to date and that the Purchaser may lose all or a
         substantial portion of his or its investment in Aesgen. The Purchaser
         (i) has adequate financial means of providing for current needs and
         possible personal contingencies after purchasing the Subscribed Shares,
         (ii) has no current need for liquidity in the Purchaser's investment in
         the Subscribed Shares, (iii) is able to bear the substantial economic
         risks of an investment in the Subscribed Shares for an indefinite
         period, and (iv) at the present time, could afford a complete loss of
         such investment.

                  (i) The Purchaser has received the Confidential Offering
         Memorandum dated September 17, 2001 ("Offering Memorandum") and has had
         an opportunity to discuss the business, management and financial
         affairs of Aesgen and the terms and conditions of an investment in the
         Subscribed Shares with, and has had access to, the management of
         Aesgen. The Purchaser has carefully reviewed the Risk Factors set forth
         in the Offering Memorandum.

                  (j) Neither Aesgen nor any person acting on its behalf has
         offered to sell to the Purchaser the Subscribed Shares by means of any
         form of general solicitation or advertising such as media advertising
         or seminars. The Purchaser acknowledges that his or her investment
         decision has not been based on any representation except as set forth
         in this Agreement and the Offering Memorandum.

                  (k) All information which the Purchaser has provided to
         Aesgen, including all information contained herein and in the
         Questionnaire provided by the Aesgen, is true, correct and complete as
         of the date hereof, and if there should be any adverse change in such
         information, the Purchaser shall immediately notify Aesgen thereof.

         SECTION 4. REPRESENTATIONS AND WARRANTIES OF AESGEN.

         Aesgen represents and warrants to the Purchaser that:

                  (i) Aesgen has all requisite power and authority to enter into
         this Agreement and to consummate the transactions contemplated hereby.
         The execution, delivery and performance by Aesgen of this Agreement and
         the issuance by Aesgen of the Accepted Shares have been duly authorized
         by all action on Aesgen's part.

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                  (ii) This Agreement has been duly executed and delivered by
         Aesgen and constitutes the legal, valid and binding obligation of
         Aesgen, enforceable in accordance with its terms subject, as to
         enforcement of remedies, to general equity principles and to applicable
         bankruptcy, insolvency and similar laws and moratorium from time to
         time in effect.

                  (iii) The Accepted Shares, when issued and delivered in
         accordance with this Agreement, will be duly authorized, validly
         issued, fully paid and non-assessable shares of Series D Preferred
         Stock of Aesgen, with no personal liability attaching to the ownership
         thereof. Upon issuance, sale and delivery of, and payment for, the
         Accepted Shares, the Purchaser will acquire good and marketable title
         thereto, free and clear of all liens, encumbrances, restrictions on
         transfer, options, charges, security interests, equities and claims
         whatsoever other than as may arise solely pursuant to the terms of the
         Amended and Restated Stockholders' Agreement dated as of January 30,
         1998 among Aesgen and the stockholders named therein. The issuance,
         sale and delivery of the Accepted Shares by Aesgen pursuant to this
         Agreement is not subject to any preemptive rights of stockholders of
         Aesgen or to any right of first refusal, transfer agreement or other
         similar right in favor of any person.

         SECTION 5. MISCELLANEOUS.

                  (a) This Agreement and the Service Agreement constitute the
         entire agreement between the parties hereto with respect to the subject
         matter hereof. This Agreement may be amended only by a writing executed
         by all of the parties hereto.

                  (b) This Agreement shall be enforced, governed and construed
         in all respects in accordance with the laws of the State of Delaware.

                  (c) This Agreement may be executed in two or more
         counterparts, each of which shall be deemed an original, but all of
         which shall constitute one and the same instrument.

                  (d) Each party hereto represents that no broker, finder or
         other party has been retained by it and no broker or finder's fees or
         commissions have been agreed to be paid in connection with this
         Agreement or the transactions contemplated hereby, and each party
         agrees to indemnify and hold harmless each other party from and against
         any and all losses and other expenses caused by a violation of this
         representation.

                           [SIGNATURE PAGE TO FOLLOW]


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         IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed as of the first date written above.

                                          aaiPHARMA INCORPORATED


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



                                          AESGEN, INC.


                                          By:
                                              ----------------------------------
                                              Paul McGarty
                                              President


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