<PAGE>   1
                                                                   EXHIBIT 10.47



                                          [*] = CONFIDENTIAL TREATMENT REQUESTED



M E M O R A N D U M                                        STRICTLY CONFIDENTIAL


TO:     Trega Compensation Committee

FROM:   Bob Whitehead

DATE:   September 5, 1997

RE:     Executive Bonus Program


     The following is the proposed Trega bonus program for the balance of 1997
through June, 1998 for your review and approval.

     -    The plan will cover corporate managers (my direct reports) and as last
          year will include a provision to reward department managers (their
          direct reports)1 for significant contribution toward organizational
          goals and objectives.

     -    Total bonus compensation will be rewarded for [_________*___________]
          and [__________*____________], for [__________*__________] and in
          selected cases, for [__________*__________].

     -    Maximum payout differs on a percentage of salary basis per executive
          and is proposed as follows:



<TABLE>
<CAPTION>
          Key Executive                    Incumbent                                     Percentage of Bonus On:
          -------------                    ---------                                     -----------------------
<S>                                       <C>                             <C>               <C>            <C>          <C>
                                                                          [*]2              [*]            [*]          [*]3

Chief Executive Officer                   R. Whitehead                    [*]               [*]            [*]          [*] *

President, R&D                            L. Muschek                      [*]               [*]            [*]          [*] *

VP, Business Development                  Open                            [*]               [*]            [*]          [*] *

VP, Finance & CFO                         Open                            [*]               [*]            [*]          [*] *

VP, Chemistry                             M. Green                        [*]               [*]            [*]          [*] *

Director, Corp. Communications            N. Wheeler                      [*]               [*]            [*]          [*] *

Director, Employee Development            S. Hanan                        [*]               [*]            [*]          [*] *
</TABLE>

-------------------
     1        [__________*__________]

     2        [__________*__________]

     3        [__________*__________]



<PAGE>   2
                                          [*] = CONFIDENTIAL TREATMENT REQUESTED



     -    Bonuses will be a mix of cash plus potential conversion of cash
          payouts in stock/options at the discretion of the Compensation
          Committee and valued using Black Shoals methodology.

     -    Based upon your approval of the general concepts, specific bonusable
          criteria sheets will be developed in concert with each executive and
          submitted to the Compensation Committee for information and
          commentary.

I look forward to your comments and suggestions.



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