THIRD AMENDMENT TO B CREDIT AGREEMENT Third Amendment (this "Amendment"), dated as of July 31, 1997 among Sherwood Medical Company, A.H. Robins Company, Incorporated and AC Acquisition Holding Company (each, a "Subsidiary Borrower"), American Home Products Corporation (the "Company", and together with the Subsidiary Borrowers, the "Borrowers"), the lending institutions party to the B Credit Agreement referred to below (the "Banks") and The Chase Manhattan Bank, as Agent (in such capacity, the "Agent"). All capitalized terms used herein and not otherwise defined shall have the respective meanings provided such terms in the B Credit Agreement referred to below. W I T N E S S E T H : WHEREAS, the Borrowers, the Banks and the Agent are parties to a Credit Agreement, dated as of September 9, 1994 (as heretofore amended, the "B Credit Agreement"); WHEREAS, the parties hereto wish to amend the B Credit Agreement as herein provided; NOW THEREFORE, it is agreed: 1. The first recital of the B Credit Agreement is hereby amended by deleting the amount "3,000,000,000" in its entirety and inserting in lieu thereof the amount of "2,500,000,000". 2. Section 1.1 of the B Credit Agreement is hereby amended by deleting the definition of "Applicable Margin" in its entirety and inserting in lieu thereof the following new definition: "Applicable Margin": for any day, the rate per annum set forth below opposite the Rating Period then in effect, it being understood that the Applicable Margin for (x) Alternate Base Rate Loans shall be the percentage set forth under the column "Alternate Base Rate Margin", (y) C/D Rate Loans shall be the percentage set forth under the column "C/D Rate Margin" and (z) Eurodollar Rate Loans shall be the percentage set forth under the column "Eurodollar Rate Margin": Alternative Eurodollar Rating Base Rate C/D Rate- Rate Period Margin Margin Margin Category A Period 0% .2300% .1050% Category B Period 0% .2500% .1250% Category C Period 0% .2525% .1275% Category D Period 0% .2850% .1600% Category E Period 0% .3500% .2250% 3. Section 1.1 of the B Credit Agreement is hereby amended by deleting the definition of "Facility Fee Percentage" in its entirety and inserting in lieu thereof the following definition: ""Facility Fee Percentage": a percentage equal to at any time (i) during a Category A Period, .0450%, (ii) during a Category B Period, .0500%, (iii) during a Category C Period, .0600%, (iv) during a Category D Period, .0900% and (v) during a Category E Period, .1250%." 4. Section 1.1 of the B Credit Agreement is hereby amended by deleting clause (a) of the definition of "Termination Date" in its entirety and inserting in lieu thereof "(a) July 31, 2002 and ". 5. In order to induce the Agent and the Banks to enter into this Amendment, the Borrowers hereby represent and warrant that (x) no Default or Event of Default exists on the Third Amendment Effective Date (as defined herein) both before and after giving effect to this Amendment and (y) all of the representations and warranties contained in the Credit Documents shall be true and correct in all material respects on the Third Amendment Effective Date both before and after giving effect to this Amendment with the same effect as though such representations and warranties had been made on and as of the Third Amendment Effective Date (it being understood that any representation or warranty made as of a specific date shall be true and correct in all material respects as of such specific date). 6. This Amendment is limited as specified and shall not constitute a modification, acceptance or waiver of any other provision of the B Credit Agreement or any other Credit Document. 7. This Amendment may be executed in any number of counterparts and by the different parties hereto on separate counterparts, each of which counterparts when executed and delivered shall be an original, but all of which shall together constitute one and the same instrument. A complete set of counterparts shall be lodged with the Company and the Agent. 8. This Amendment and the rights and obligations of the parties hereunder shall be construed in accordance with and governed by the law of the State of New York. 9. Notwithstanding anything to the contrary contained in the B Credit Agreement or this Amendment, for purposes of this Amendment "Banks" shall mean each of the lending institutions who shall have delivered (including by way of telecopier) by July 30, 1997 (or such later date as the Agent and the Company shall agree) a signed copy hereof to the Agent as provided in Section 8.2 of the B Credit Agreement that has been accepted by the Company. 10. As of the Third Amendment Effective Date, (v) Schedule I to the B Credit Agreement shall be revised to read as set forth on Annex I hereto, (w) Schedule II to the B Credit Agreement shall be revised by the Agent to give effect to such revised Schedule I and (x) the Banks shall constitute all the Lenders and no other entity that had been a Lender will continue to be a Lender, (y) either (A) all amounts owing to Lenders prior to July 30, 1997 who are not Banks (the "Former Lenders") shall be paid to such Former Lenders or (B) such Former Lenders shall assign their Commitments to one or more Banks and (z) no such Former Lender will continue to be a Lender. 11. This Amendment shall become effective as of the date hereof (the "Third Amendment Effective Date") on the date upon which (x) each of the Borrowers, the Agent and the Banks (as defined in paragraph 9) with Commitments as set forth on Annex I hereto aggregating $2,500,000,000 shall have signed a copy hereof (whether the same or different copies) and shall have delivered (including by way of telecopier) the same to the Agent as provided in Section 8.2 of the B Credit Agreement and (y) the Third Amendment to the A Credit Agreement, dated as of the date hereof, has become effective. 12. From and after the Third Amendment Effective Date, all references in the B Credit Agreement and each of the other Credit Documents to the B Credit Agreement shall be deemed to be references to the B Credit Agreement after giving effect to this Amendment. IN WITNESS WHEREOF, each of the parties hereto has caused a counterpart of this Amendment to be duly executed and delivered as of the date first above written. AMERICAN HOME PRODUCTS CORPORATION By:_________________________________ Title: Vice President - Finance SHERWOOD MEDICAL COMPANY By: Title: Vice President A. H. ROBINS COMPANY, INCORPORATED By:_________________________________ Title: Vice President and Treasurer AC ACQUISITION HOLDING COMPANY By:_________________________________ Title: Vice President and Treasurer BANCA COMMERCIALE ITALIANA NEW YORK BRANCH By:_________________________________ Title: Charles Daugherty,Vice President By:_________________________________ Title: K. Purelis, Vice President BANCA DI ROMA By:_________________________________ Title: Virgina Mahler Cosenza Assistant Vice President By:_________________________________ Title: Vice President BANCA MONTE DEI PASCHI DI SIENA, S.p.A. By:_________________________________ Title: S.V.P. and General Manager By:_________________________________ Title: Brian R. Landy Vice President BANCA NAZIONALE DEL LAVORO S.p.A. NEW YORK BRANCH By:_________________________________ Title: Giuliano Violetta First Vice President By:_________________________________ Title: Giulio Giovine Vice President BANCA POPOLARE DI MILANO By:_________________________________ Title: Anthony Franco Executive Vice President & GM By:_________________________________ Title: Fulvio Montanari First Vice President BANK OF AMERICA NT & SA By:_________________________________ Title: Vice President BANK OF IRELAND By:_________________________________ Title: BANK OF MONTREAL By:_________________________________ Title: Sharron P. Walsh Director THE BANK OF NEW YORK By:_________________________________ Title: Vice President THE BANK OF NOVA SCOTIA By:_________________________________ Title: Vice President THE BANK OF TOKYO-MITSUBISHI TRUST COMPANY, as Co-Agent By:_____________________________ Title: Vice President BANKERS TRUST COMPANY By:_________________________________ Title: Vice President BANQUE NATIONALE DE PARIS NEW YORK BRANCH By:____________________________________ Title: Richard L. Sted Senior Vice President By:_________________________________ Title: Richard Pace Vice President, Corporate Banking Division CARIPLO - CASSA DI RISPARMIO DELLE PROVINCIE LOMBARDE SPA By:_____________________________ Title: F. Vice President By:_____________________________ Title: F. Vice President THE CHASE MANHATTAN BANK, as Administrative Agent By:_________________________________ Title: Managing Director CITIBANK, N.A., as Co-Agent By:_________________________________ Title: Mary W. Corkran Vice President COMMERZBANK AKTIENGESELLSCHAFT New York and/or Grand Cayman Branches, as Co-Agent By:__________________________________ Title: By:__________________________________ Title: A. Oliver Welsch-Lehmann Assistant Treasurer COOPERATIEVE CENTRALE RAIFFEISEN- BOERENLEENBANK, B.A., "RABOBANK NEDERLAND" By:_________________________________ Title: Ellen A. Polansky Vice President By:_________________________________ Title: W. Pieter C. Kodde Vice President CORESTATES BANK, N.A., as co-Agent By:_____________________________ Title: Vice President CRESTAR BANK By:__________________________________ Title: Senior Vice President THE DAI-ICHI KANGYO BANK LTD., as co-Agent By:__________________________________ Title: Vice President THE FIRST NATIONAL BANK OF CHICAGO, as co-Agent By:_____________________________ Title: Corporate Banking Officer FLEET NATIONAL BANK By:_____________________________ Title: Assistant Vice President THE FUJI BANK, LIMITED, as co-Agent By:_________________________________ Title: Senior Vice President ISTITUTO BANCARIO SAN PAOLO DI TORINA S.p.A. - NEW YORK LIMITED BRANCH, as co-Agent By:___________________________________ Title: Vice President By:_________________________________ Title: Vice President MELLON BANK, N.A. By:_____________________________ Title: Vice President MARINE MIDLAND BANK By:_________________________________ Title: William M. Holland Vice President THE MITSUBISHI TRUST AND BANKING CORPORATION By:_________________________________ Title: Deputy General Manager MORGAN GUARANTY TRUST COMPANY OF NEW YORK, as co-Agent By:_________________________________ Title: Charles H. King Vice President NATIONAL WESTMINSTER BANK PLC By:_________________________________ Title: Vice President NATIONSBANK, N.A., as co-Agent By:_________________________________ Title: Senior Vice President THE NORINCHUKIN BANK, NEW YORK BRANCH By:_________________________________ Title: Takeshi Akimoto General Manager THE NORTHERN TRUST COMPANY By:_________________________________ Title: Vice President PNC BANK, NATIONAL ASSOCIATION By:_________________________________ Title: Vice President ROYAL BANK OF CANADA By:_________________________________ Title: Manager ROYAL BANK OF CANADA GRAND CAYMAN BRANCH By:_________________________________ Title: Senior Manager THE SAKURA BANK, LIMITED By:_________________________________ Title: Yasumasa Kikuchi Senior Vice President THE SANWA BANK LTD, NEW YORK BRANCH By:_________________________________ Title: Joseph E. Leo Vice President & Area Manager STANDARD CHARTERED BANK By:_________________________________ Title: Brian S. Taylor Vice President THE SUMITOMO TRUST & BANKING CO., LTD, NEW YORK BRANCH By:_________________________________ Title: Suraj Bhatia Senior Vice President THE SUMITIMO TRUST & BANKING CO. By:_________________________________ Title: SUNTRUST BANK, INC. By:_________________________________ Title: Group Vice President SWISS BANK CORPORATION, NEW YORK BRANCH as co-Agent By:_________________________________ Title: William S. Lutkins Associate Director, Credit Risk Management By:_________________________________ Title: Dorothy L. McKinley Associate Director, Banking Finance Support, N.A. THE TOKAI BANK, LIMITED NEW YORK BRANCH By:_________________________________ Title: Deputy General Manager TORONTO DOMINION (NEW YORK), INC. By:_________________________________ Title: Debbie A. Greene Vice President THE TOYO TRUST & BANKING CO., LTD. NEW YORK BRANCH By:_________________________________ Title: Vice President WACHOVIA BANK OF GEORGIA, N.A., as co-Agent By:_________________________________ Title: Vice President