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                                                                   EXHIBIT 10.6
                                                                 EXECUTION COPY
    
 
                                  AMENDMENT TO
                                 EXECUTION COPY
                       RESEARCH AND DEVELOPMENT AGREEMENT
                                 BY AND BETWEEN
              BIOCHEM PHARMA INC. AND CLINICHEM DEVELOPMENT INC.,
 
     THIS AMENDMENT (the "Amendment"), made and entered into as of the 4th day
of May, 1998 (the "Effective Date"), is by and between BIOCHEM PHARMA INC., a
Canadian corporation ("BioChem") and CLINICHEM DEVELOPMENT INC., a Canadian
corporation ("CliniChem").
 
     WHEREAS, BioChem and CliniChem are parties to that certain Research and
Development Agreement dated March 31, 1998 (the "Original Agreement");
 
     WHEREAS, BioChem and CliniChem desire to amend the Original Agreement as
set forth herein; and
 
     WHEREAS, capitalized terms used but not otherwise defined herein shall have
the meaning ascribed to them in the Original Agreement;
 
     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties agree as follows:
 
1.   Article 1.3 of the Original Agreement shall be amended to read:
 
     "Available Funds"  shall mean, as of any date of determination, all of the
     funds contributed to CliniChem by BioChem or a BioChem Affiliate, plus any
     investment income earned thereon, less (a) the aggregate amount of all
     Research and Development Costs paid or incurred by CliniChem as of such
     date, (b) CliniChem's aggregate reasonable ongoing administrative expenses
     and income taxes paid (less income taxes refunded) or incurred as of such
     date, (c) the aggregate amount of all Technology Fee payments paid or
     incurred by CliniChem as of such date, (d) the aggregate amount of all
     payments paid or incurred by CliniChem under the Services Agreement and (e)
     reasonable amounts actually paid by CliniChem for consultants to advise the
     Board of Directors of CliniChem with respect to the CliniChem Products and
     the CliniChem Programs. Available Funds shall not include payments made by
     BioChem to CliniChem pursuant to the Product Option Agreement.
 
2.   Article 2.3(c) of the Original Agreement shall be amended to read:
 
     The parties recognize that bona fide disputes may arise from time to time
     in connection with devising mutually-acceptable Work Plans for the
     CliniChem Programs. If CliniChem's Board of Directors accepts or rejects a
     Work Plan in part, BioChem may either (i) perform the activities under the
     Work Plan as approved by CliniChem or (ii) propose a modified Work Plan to
     CliniChem for approval. Notwithstanding the foregoing, in the event
     CliniChem's Board of Directors rejects in whole or in substantial part
     three consecutive Work Plans proposed by BioChem with respect to a
     particular CliniChem Program, BioChem and CliniChem shall resolve the
     dispute in accordance with the provisions of Section 12.3 of this
     Agreement. Prior to the resolution of any such dispute, BioChem shall have
     the right to perform the work specified under its most recently approved
     Work Plan and CliniChem shall be obligated to pay the Research and
     Development Costs incurred in connection therewith.
 
3.   Article 3.1 of the Original Agreement shall be amended to read:
 
     Payment of Research and Development Costs.  In consideration of the work to
     be carried out by BioChem hereunder, CliniChem shall make payments to
     BioChem or its Affiliates for all Research and Development Costs incurred
     by BioChem or its Affiliates in accordance with accepted Work Plans up to
     the maximum amount of Available Funds. CliniChem shall make payments to
     BioChem for Research and Development Costs with respect to the initial
     CliniChem Programs which are incurred from the date of the declaration of
     the Distribution.
 
4.   Article 9.1 of the Original Agreement shall be amended to read:

   

    
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     Use of Available Funds.  Unless BioChem agrees otherwise, CliniChem agrees
     to expend the Available Funds only for activities undertaken pursuant to
     this Agreement and for payments due to BioChem or a BioChem Affiliate under
     this Agreement, the Technology License Agreement and the Services
     Agreement. Pending application of all Available Funds as set forth above,
     Available Funds shall be invested in interest-bearing, investment-grade
     securities.
 
5.   As amended hereby, the Original Agreement shall remain in full force and
effect.
 
     IN WITNESS HEREOF, the parties have executed this Amendment as of the
     Effective Date by their duly authorized representatives.
 

                                              
BIOCHEM PHARMA INC.                              CLINICHEM DEVELOPMENT INC.
 
By:                                              By:
Title:                                           Title:
 
By:                                              By:
Title:                                           Title: