EXHIBIT (e)(12)



                   AMENDMENT TO AGREEMENT AND PLAN OF MERGER
                                  BY AND AMONG
      PFIZER, INC., ENZO ACQUISITION CORP. AND ESPERION THERAPEUTICS, INC.


        This Amendment, dated of as January 16, 2004 (this "Amendment"), amends
the Agreement and Plan of Merger, dated as of December 19, 2003 (the
"Agreement"), by and among Pfizer Inc., a Delaware corporation ("Parent"), Enzo
Acquisition Corp., a Delaware corporation ("Merger Sub"), and Esperion
Therapeutics, Inc., a Delaware corporation (the "Company"). Capitalized terms
used herein but not defined shall have the meanings assigned to such terms in
the Agreement.

        WHEREAS, each of the parties hereto has determined that it is desirable
to amend the Agreement as set forth in this Amendment.

        NOW, THEREFORE, in consideration of the foregoing and the mutual
covenants and agreements herein contained, and intending to be legally bound
hereby, Parent, Merger Sub and the Company hereby agree as follows:

        1. The first sentence of Section 7.03(d) of the Agreement is hereby
amended by changing "January 16, 2004" to "on or about January 20, 2004."

        2. Parent and Merger Sub shall promptly amend the Offer Documents, and
the Company shall promptly amend the Schedule 14D-9, in each case as filed with
the SEC, as appropriate to reflect the terms of this Amendment.

        3. Except as specifically amended by this Amendment, the Agreement shall
remain in full force and effect.

        4. This Amendment shall be governed by, and construed in accordance
with, the Laws of the State of Delaware applicable to contracts executed in and
to be preformed in that State.

        5. This Amendment may be executed in two or more counterparts (delivery
of which may occur via facsimile), each of which shall be binding as of the date
first written above, and, when delivered, all of which shall constitute one and
the same instrument. A facsimile signature or electronically scanned copy of a
signature shall constitute and shall be deemed sufficient evidence of a party's
execution of this Amendment, without necessity of further proof. Each such copy
shall be deemed an original, and it shall not be necessary in making proof of
this Amendment to produce or account for more than one such counterpart.





            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK.]







        IN WITNESS WHEREOF, Parent, Merger Sub and the Company have duly
executed this Amendment as of the day and year first written above.


                                          PFIZER INC.


                                          By:  /s/ David Reid
                                               ---------------------------
                                          Name: David Reid
                                          Title: Assistant Secretary


                                          ENZO ACQUISITION CORP.

                                          By:  /s/ David Reid
                                               ---------------------------
                                          Name: David Reid
                                          Title: Vice President and Secretary


                                          ESPERION THERAPEUTICS, INC.


                                          By:  /s/ Roger S. Newton, Ph.D.
                                               ---------------------------
                                          Name: Roger S. Newton, Ph.D.
                                          Title: President and Chief
                                                 Executive Officer