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                                                                    EXHIBIT 10.2

                                 AMENDMENT NO. 1
                                       TO
                               PURCHASE AGREEMENT

     This AMENDMENT NO. 1 (the "Amendment") to the Purchase Agreement, dated as
of November 6, 2001 (the "Purchase Agreement") among American Home Products
Corporation, a Delaware corporation ("AHP"), AHP Subsidiary Holding Corporation,
a Delaware corporation ("Holdings" and, together with AHP, the "Sellers"), and
Immunex Corporation, a Washington corporation ("Buyer"), is entered into as of
December 21, 2001.

                              W I T N E S S E T H :
                              - - - - - - - - - -

     WHEREAS, AHP, Holdings and Buyer each desire to amend the Purchase
Agreement as set forth herein;

     NOW THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:

1.   Amendments to the Purchase Agreement.

     (a) The following shall be added as a new Section 2.5 of the Purchase
Agreement:

     "2.5 PAYMENT METHOD.

     Notwithstanding anything to the contrary herein, all payments required to
     be made by Buyer to Holdings at Closing pursuant to Sections 2.1 and 2.2 of
     this Agreement shall be made by tender at Closing of a duly authorized and
     executed Note (the "Note") in the form attached as Exhibit 2.5(a) hereto.
                         ----
     The Note shall be due and payable by wire transfer of immediately available
     funds on or before January 11, 2002 to an account specified in writing by
     the Sellers. The Note shall be secured by the Shares, which shall be
     pledged to Holdings at Closing pursuant to the Pledge Agreement attached
     hereto as Exhibit 2.5(b). The pledged Shares shall be released to Buyer
     upon payment of the Note in accordance with the terms of the Pledge
     Agreement."

     (b) Section 3.1 of the Purchase Agreement is hereby amended and restated to
read in its entirety:

     "3.1. THE CLOSING. Unless this Agreement shall have been terminated in
     accordance with the terms hereof, on the terms and subject to the
     conditions of this Agreement, the closing of the sale and purchase of the
     Shares and the Assets and the consummation of the other transactions

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     contemplated hereby (the "Closing") shall take place at the offices of
                               -------
     American Home Products Corporation, Five Giralda Farms, Madison, New
     Jersey, 07940 on (a) the later of January 1, 2002; or (ii) the next
     succeeding business day on which the last to be fulfilled or waived of the
     conditions set forth in Article 9 shall be fulfilled or waived in
     accordance with this Agreement or (b) at such other time, date or place as
     the parties may mutually agree upon in writing (the "Closing Date"). At the
     Closing, the parties to this Agreement will exchange the Note, certificates
     and other documents specified in this Agreement, and ownership of the
     Shares will transfer to Buyer notwithstanding Sellers' continued possession
     of the Certificate (as defined below) under the Pledge Agreement. For
     purposes of this Agreement, the Closing will be treated as if it had
     occurred at 12:01 a.m. on the Closing Date."

     (c) Section 3.2(a) of the Purchase Agreement is hereby amended and restated
to read in its entirety:

     "3.2(a) the Note and the Pledge Agreement;"

     (d) Section 3.3(a) of the Purchase Agreement is hereby amended and restated
to read in its entirety:

     "3.3(a) a photocopy of a certificate representing the Shares (the
     "Certificate"), which has been duly endorsed for transfer to Buyer or is
      -----------
     accompanied by a stock power duly executed in blank, it being understood
     that Sellers shall retain possession of the original Certificate in
     accordance with the terms of the Pledge Agreement."

     (e) The following shall be added as a new Section 4.18 of the Purchase
Agreement:

     "4.18.  PAST ACTIVITIES. Greenwich was, prior to July 16, 1999, solely a
      holding company owning the shares of Promotion Services GmbH and did
      not engage in any activity or operations before July 16, 1999.
      Promotion Services GmbH never engaged, directly or indirectly, in the
      sale or distribution of any pharmaceutical or other products. All
      actions necessary to effect the dissolution of Promotion Services GmbH
      in full compliance with applicable law, including any necessary actions
      of any governmental entity or agency, have been taken and such
      dissolution is complete, effective November 29, 2001. As of the Closing
      Date, there are no claims, actions, suits, arbitrations, investigations
      or proceedings pending against or involving, or to the knowledge of
      Sellers, threatened against Promotion Services GmbH and, to the
      knowledge of Sellers, there is no valid basis for any claim, action,
      suit, arbitration, proceeding or investigation before or by any Person
      against or involving Promotion Services GmbH. There are no outstanding
      judgments, orders, decrees, or stipulations to which Promotion Services

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     GmbH is a party. Promotion Services GmbH has not engaged in any operations
     or business activity since March 31, 1996."

     (f) The following shall be added as a new Section 4.19 to the Purchase
Agreement:

     "4.19. SUBSIDIARIES. Greenwich does not own or control, and except for
     Promotion Services GmbH, has never owned or controlled, directly or
     indirectly, any corporation, partnership, limited liability company or
     other business entity. Greenwich does not own or control, and except for
     Promotion Services GmbH has never owned or controlled, directly or
     indirectly, any ownership, equity or voting interest in, any corporation,
     partnership, joint venture or other entity, and has no agreement or
     commitment to purchase any such interest."

     (g) Section 11.1(c) and (d) are hereby amended and restated to read in
their entirety as follows, and the following shall be added as a new Section
11.1(e) and a new Section 11(f) to the Purchase Agreement:

     "11.1(c) any Excluded Assets and Liabilities; (d) the operation and
     activities of Greenwich, and the ownership of its assets, prior to
     September 24, 1999 and all operations and activities of Promotion
     Services GmbH; (e) that certain complaint of Thomas E. Angelone against
     Wyeth Pharmaceuticals currently pending before the Equal Employment
     Opportunity Commission and the Rhode Island Commission for Human
     Rights; and (f) any and all actions, suits, proceedings, claims, and
     demands incident to any of the foregoing or such indemnification."

     (h) Section 11.3(a) is hereby amended and restated to read in its entirety:

     "11.3. CERTAIN LIMITATIONS. (a) Other than Sellers' obligation to indemnify
     for Buyer Losses under Section 11.1(a) of this Agreement arising out of a
     breach of representation or warranty contained in Section 4.2
     (capitalization), 4.12 (brokers), 4.15 (taxes), 4.18 (past activities) or
     4.19 (subsidiaries), Sellers' obligation to indemnify for Buyer Losses
     under Section 11.1(a) of this Agreement shall not accrue until the
     aggregate of all such Buyer Losses exceeds Seven Hundred Fifty Thousand
     Dollars ($750,000) (the "Loss Threshold") and then Sellers shall be liable
     for all such Buyer Losses in excess of such initial $750,000 and shall be
     limited to One Hundred Seventy-Five Million Dollars ($175,000,000) in the
     aggregate. There shall be no Loss Threshold or limit on liability with
     respect to Sellers' obligations to indemnify under Sections 11.1(b)
     through (f)."

     (i)  Section 12.1 is hereby amended and restated to read in its entirety:

     "The covenants contained in this Agreement shall survive the Closing
     Date without limitation except as expressly set forth herein. The
     representations and warranties contained herein shall survive the
     Closing Date for a period of eighteen (18) months, except for (i) the
     representations and warranties contained in Section 4.15 (taxes), which
     shall survive until the expiration of the applicable statute of
     limitations, and (ii) the representations and warranties contained in
     Sections 4.2 (capitalization),

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     4.3 (corporate authority), 4.12 (brokers and intermediaries), 4.18 (past
     activities), 4.19 (subsidiaries), 5.2 (corporate authority) and 5.5
     (brokers and intermediaries), which shall survive the Closing Date
     without limitation. Buyer's and Seller's right to make a claim for
     indemnification under Section 11.1(a) or Section 11.2(a), respectively for
     a breach of any representation or warranty expires upon the expiration of
     the applicable period set forth above, it being understood that claims made
     on or prior to such expiration date shall survive such expiration date."

2. Reference to and Effect on Purchase Agreement; Miscellaneous.

     (a) Upon the effectiveness of this Amendment, each reference in the
Purchase Agreement to "this Agreement," "hereunder," "hereof, " "herein, "
"hereby" or words of like import shall mean and be a reference to the Purchase
Agreement as amended hereby, and each reference to the Purchase Agreement in any
other document, instrument or agreement executed and/or delivered in connection
with the Purchase Agreement shall mean and be a reference to the Purchase
Agreement as amended hereby.

     (b) The execution, delivery and effectiveness of this Amendment shall
not operate as a waiver of either of the parties under the Purchase Agreement
nor constitute a waiver of any provision contained therein, except as
specifically set forth herein or contemplated hereby.

     (c) This Amendment may be executed and delivered (including by
facsimile transmission) in any number of counterparts, and by the different
parties hereto in separate counterparts, each of which when executed and
delivered shall be deemed to be an original and all of which taken together
shall constitute but one and the same instrument.

     (d) Section headings in this Amendment are included herein for
reference purposes only and shall not affect in any way the meaning or
interpretation of this Amendment.

                            [Signature page follows.]

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     IN WITNESS WHEREOF, the parties have entered into and signed this
Amendment as of the date and year first written above.

                                    AMERICAN HOME PRODUCTS CORPORATION



                                    By: /s/ Thomas M. Nee
                                        ------------------------------------
                                        Title:______________________________


                                    AHP SUBSIDIARY HOLDING CORPORATION



                                    By: /s/ Timothy Slater
                                        ------------------------------------
                                        Title:______________________________


                                    IMMUNEX CORPORATION


                                    By: /s/ David A. Mann
                                        ------------------------------------
                                        Title:______________________________


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