EXHIBIT 10.20(B) AMENDMENT TO STOCK OPTION AGREEMENT

                                                                EXHIBIT 10.20(B)
                                    AMENDMENT
                                       TO
                             STOCK OPTION AGREEMENT

      AMENDMENT made this 29th day of January to the Stock Option Agreement
between Xxxxxx Pharmaceuticals, Inc. (the "Company") (as successor to the Royce
Laboratories, Inc. ("Royce") options) and Xxxxxxx X. XxXxxxx ("XxXxxxx") dated
July 8, 1991(the "Option").

                                   WITNESSETH:

      WHEREAS, the Option is a nonstatutory option and the Option expires and
becomes non-exercisable on the date that XxXxxxx resigns from the employ of
Royce ;

      WHEREAS, XxXxxxx will be resigning from Royce effective January 30, 1998
(the "Termination Date"); and

      WHEREAS, XxXxxxx desires and the Company is willing to extend the period
during which the Option may be exercised for a period ending on April 30, 1998,
which is 90 days following the Termination Date.

      NOW, THEREFORE, for good and valuable consideration, Section 2.2 of the
Option is hereby amended to read as follows:

      2.2   DISCHARGE OR RESIGNATION.

      (a)  If an Optionee ceases to be an employee of the Company, by reason of
           the fact that he is discharged for cause, as determined solely and
           exclusively by the committee appointed by the Board to administer
           this Option (the "Committee"), all rights of the Optionee to exercise
           the Options granted hereunder shall terminate, lapse and be forfeited
           at the time of Optionee's termination of employment.

      (b)  If an Optionee ceases to an employee of the Company by reason of his
           resignation or voluntary action, all rights of Optionee to exercise
           the Options granted hereunder shall terminate, lapse and be forfeited
           on the date which is 90 days following such resignation or voluntary
           action.

      The Option shall remain in full force and effect in all other respects.

      This Amendment shall be effective immediately.

      IN WITNESS WHEREOF, the parties have executed this Amendment in multiple
counterparts, each of which shall be treated as an original, as of the day and
year first written above.

ATTEST:                             XXXXXX PHARMACEUTICALS, INC.


____________________________        By _____________________________
                                         Its________________________


                                    OPTIONEE:


                                    _________________________________
                                           Xxxxxxx X. XxXxxxx