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                                                                  EXHIBIT 10.45
                                   Procept, Inc.
                             Procept Acquisition Corp.
                                 840 Memorial Drive
                                Cambridge, MA  02139


                                   February 8, 1999



Pacific Pharmaceuticals, Inc.
6730 Mesa Ridge Road, Suite A
San Diego, CA  92121

Re:  Amendment to Agreement and Plan of Merger
     -----------------------------------------

Dear Sirs or Madams:

          On December 10, 1998, Procept, Inc., a Delaware corporation
("Procept"), Pacific Pharmaceuticals, Inc., a Delaware corporation ("Pacific"),
and Procept Acquisition Corp., a Delaware corporation ("PAC"), entered into an
Agreement and Plan of Merger (the "Merger Agreement").  Capitalized terms used
herein but not otherwise defined shall have the meanings ascribed to them in the
Merger Agreement.  

          Pursuant to the merger contemplated by the Merger Agreement (the
"Merger"), each holder of Pacific's Series A Convertible Preferred Stock, $25.00
par value ("Pacific Preferred Stock"), shall receive shares of Procept Common
Stock (the "Merger Shares") and certain contractual rights set forth in Section
10 of the Merger Agreement (the "Section 10 Rights").  It is the parties
understanding that, under present circumstances, the issuance of Procept Common
Stock to the holders of Pacific Common Stock in the Merger will cause a Dilution
Event (the "Merger Dilution Event") under the anti-dilution rights contained in
Article VI of Subscription Agreements entered into by certain holders of Procept
Common Stock who purchased their shares in a 1998 private placement (the
"Article VI Rights Holders").

          The parties hereby confirm that it is their intent that the Merger
have the equivalent effect for the holders of Pacific Preferred Stock and the
Article VI Rights Holders.  Accordingly, notwithstanding anything to the
contrary set forth in the Merger Agreement, the parties hereby agree that the
holders of Pacific Preferred Stock shall receive such number of additional
shares of Procept Common Stock (the "Dilution Shares") as they would have
received due to the Merger Dilution Event had they been Article VI Rights
Holders immediately prior to the time of the Merger.  (Under present
circumstances, the parties understand and agree that 417,137 Dilution Shares
shall be issued to holders of Pacific Preferred Stock due to the Merger Dilution
Event).
                                     
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          If the foregoing is in accordance with your understanding of our
agreement, please sign and return to Procept a counterpart hereof, whereupon
this instrument, together with all counterparts, will become a binding agreement
in accordance with its terms.

                                   Very truly yours,

                                   PROCEPT, INC.


                                   By:   /s/ John F. Dee
                                     ------------------------------
                                        John F. Dee
                                        President and CEO


                                   PROCEPT ACQUISITION CORP.


                                   By:   /s/ John F. Dee
                                      -----------------------------
                                        John F. Dee
                                        President and CEO


Confirmed, accepted and agreed to
as of the date first above written

PACIFIC PHARMACEUTICALS, INC.


By:   /s/ Anil K. Singhal
     --------------------
     Anil K. Singhal
     Interim President and CEO



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