1
                                                                    Exhibit 2.6
                                                         AS EXECUTED - CONFORMED

               KBI SUB ASSIGNMENT AND ASSUMPTION AGREEMENT (#2)

            ASSIGNMENT AND ASSUMPTION AGREEMENT, dated as of July 1, 1998,
between KBI SUB INC., a Delaware corporation ("KBI Sub"), and ASTRA
PHARMACEUTICALS, L.P., a Delaware limited partnership (the "Partnership").

                                   WITNESSETH:

            WHEREAS, Astra AB, a company limited by shares organized and
existing under the laws of Sweden ("KB"), Merck & Co., Inc., a New Jersey
corporation ("TR"), Astra Merck Inc., a Delaware corporation ("KBI"), KBI Sub,
the Partnership and other related parties have entered into that certain Master
Restructuring Agreement dated as of June 19, 1998 (the "Master Restructuring
Agreement");

            WHEREAS, KB, TR, KBI and KBI Sub have executed and delivered the KBI
Asset Contribution Agreement dated as of June 19, 1998 (the "KBI Asset
Contribution Agreement") providing for the transfer and assignment of certain
assets of KBI to KBI Sub and the assumption by KBI Sub of certain liabilities
and obligations of KBI;

            WHEREAS, KB, TR, KBI and KBI Sub have executed and delivered the
Trademark Rights Contribution Agreement of even date herewith (the "Trademark
Agreement") providing for the transfer and assignment to KBI Sub of the rights
of KBI under the Amended and Restated KBI License (as defined in the Master
Restructuring Agreement) with respect to Trademarks (as defined in the Amended
and Restated KBI License) and the assumption by KBI Sub of the liabilities and
obligations of KBI under the Amended and Restated KBI License relating to the
Trademarks;

            WHEREAS, KB, TR, KBI-E and KBI Sub have executed and delivered the
KBI-E Asset Contribution Agreement dated as of June 19, 1998 (the "KBI-E Asset
Contribution Agreement") providing for the transfer and assignment to KBI Sub of
the rights and obligations of KBI-E under (i) the Amended and Restated KBI
License with respect to the Selected Uses (as defined in the Master
Restructuring Agreement) of the Compounds (as defined in the Master
Restructuring Agreement) omeprazole and felodipine, (ii) the
Omeprazole-for-Horses License (as defined in the Master Restructuring Agreement)
and (iii) the Transferred Contracts (as defined in the KBI Asset Contribution
Agreement);

            WHEREAS, KBI Sub desires to transfer and assign all of its rights
and obligations under the KBI Asset Contribution Agreement, the Trademark
Agreement and the KBI-E Asset Contribution Agreement to the Partnership, and the
Partnership desires to accept and assume such rights and obligations, all in
accordance with the terms and conditions of this Agreement and the Master
Restructuring Agreement;

            NOW, THEREFORE, in consideration of the premises and the agreements
contained herein and in the Master Restructuring Agreement, the parties hereby
agree as follows:
   2
                                                                               2

            1. Definitions. Capitalized terms that are used herein and not
otherwise defined shall have the respective meanings assigned to them in the KBI
Asset Contribution Agreement, the Trademark Agreement and the KBI-E Asset
Contribution Agreement.

            2. Assignment. Effective at and as of the Effective Time (as defined
in the Master Restructuring Agreement), KBI Sub hereby conveys, grants,
transfers, sets over, assigns and delivers to the Partnership all of KBI Sub's
rights in and under the KBI Asset Contribution Agreement, the Trademark
Agreement and the KBI-E Asset Contribution Agreement.

            3. Assumption. Effective at and as of the Effective Time, the
Partnership, without any further responsibility or liability of, or recourse to,
TR, KBI, KBI-E, KBI Sub or any of their respective directors, shareholders,
officers, employees, agents, consultants, representatives, Affiliates,
successors or assigns hereby absolutely and irrevocably assumes and is, and
shall be, liable and solely responsible for any and all liabilities and
obligations of KBI Sub under or pursuant to the KBI Asset Contribution
Agreement, the Trademark Agreement and the KBI-E Asset Contribution Agreement,
including without limitation all Assumed Liabilities (as defined in the KBI
Asset Contribution Agreement), all Trademark Liabilities (as defined in the
Trademark Agreement) and all KBI-E Assumed Liabilities (as defined in the KBI-E
Asset Contribution Agreement).

            4. Performance of Obligations by the Partnership; Indemnification.
(a) The Partnership covenants and agrees to perform and satisfy fully, on or
before the date when due, all obligations included in, arising from, or related
to, the Assumed Liabilities, the Trademark Liabilities and the KBI-E Assumed
Liabilities so that TR, KBI, KBI-E, KBI Sub and all of their respective
directors, shareholders, officers, employees, agents, consultants,
representatives, Affiliates, successors or assigns have no liability or
obligations with respect thereto.

            (b) The Partnership agrees to indemnify, defend and hold harmless
KBI Sub and its Affiliates and their respective officers, directors, employees
and agents from and against any and all Indemnity Losses (as defined in the
Master Restructuring Agreement) arising out of, based upon or resulting from (i)
the liabilities and obligations of KBI Sub under the KBI Asset Contribution
Agreement, the Trademark Agreement and the KBI-E Asset Contribution Agreement,
(ii) the Assumed Liabilities, (iii) the Trademark Liabilities and (iv) the KBI-E
Assumed Liabilities. Any claim for indemnification hereunder shall be on a
net-after tax basis in accordance with, and shall be subject to the procedures
set forth in, Section 10.3 of the Master Restructuring Agreement.

            5. Equal Knowledge. KBI Sub and the Partnership hereby acknowledge
and agree that each of them has equal knowledge regarding KBI, the Business, the
Acquired Assets, the Assumed Liabilities, the Trademarks, the Trademark
Liabilities, the KBI-E Acquired Assets and the KBI-E Assumed Liabilities, as
such terms are defined in the KBI Asset Contribution Agreement, the Trademark
Agreement and the KBI-E Asset Contribution Agreement.

            6. Warranty Disclaimer. KBI SUB MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND OR CHARACTER, EXPRESS OR IMPLIED, EITHER
   3
                                                                               3

HEREIN OR OTHERWISE, AS TO THE BUSINESS, THE ACQUIRED ASSETS, THE ASSUMED
LIABILITIES, THE TRADEMARKS, THE TRADEMARK LIABILITIES, THE KBI-E ACQUIRED
ASSETS, THE KBI-E ASSUMED LIABILITIES, THE TRANSACTIONS CONTEMPLATED HEREBY OR
ANY OTHER MATTER PERTAINING TO ANY OF THE FOREGOING. WITHOUT LIMITING THE
FOREGOING, THE ACQUIRED ASSETS, THE RIGHTS WITH RESPECT TO THE TRADEMARKS AND
THE KBI-E ACQUIRED ASSETS ARE BEING CONVEYED, TRANSFERRED, ASSIGNED AND
DELIVERED AND THE ASSUMED LIABILITIES, THE TRADEMARK LIABILITIES AND THE KBI-E
ASSUMED LIABILITIES ARE BEING ASSUMED "AS IS" AND "WHERE IS" AND KBI SUB HEREBY
DISCLAIMS ALL REPRESENTATIONS AND WARRANTIES, EXPRESS OR IMPLIED, AS TO THE
CONDITION OF THE BUSINESS, THE ACQUIRED ASSETS, THE TRADEMARKS AND THE KBI-E
ACQUIRED ASSETS, INCLUDING, WITHOUT LIMITATION, THE WARRANTY OF MERCHANTABILITY
OR FITNESS FOR A PARTICULAR PURPOSE OR OTHERWISE. The Partnership acknowledges
and agrees that it has not relied on any representation, warranty or statement
made, or any information provided, by or on behalf of KBI Sub, KBI-E, KBI, TR or
any Affiliate of TR in connection with the transactions contemplated by this
Agreement or by the KBI Asset Contribution Agreement, the Trademark Agreement or
the KBI-E Asset Contribution Agreement.

            7. Certain Related Provisions. This Agreement is subject to Articles
9, 10 and 12 of the Master Restructuring Agreement.
   4
                                                                               4

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

                                          KBI SUB INC.


                                          By:   /s/ Peter E. Nugent
                                             ----------------------------------
                                             Name:    Peter E. Nugent
                                             Title:   President




                                          ASTRA PHARMACEUTICALS, L.P.

                                          By:   KB USA, L.P., General Partner

                                          By:  ASTRA AB, General Partner
                                                 (publ)


                                          By:   /s/ Goran Lerenius
                                             ----------------------------------
                                             Name:    Goran Lerenius
                                             Title:   Authorized Signatory