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                                                                   Exhibit 10.04
                                                                   -------------

                      EMPLOYMENT AND CONSULTING AGREEMENT


     THIS EMPLOYMENT AND CONSULTING AGREEMENT (this "Agreement") is made between
                                                     ---------
Brian Frenzel ("Mr. Frenzel") and Centaur Pharmaceuticals, Inc., a Delaware
                -----------
corporation ("Centaur") effective January 1, 2000.
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                                 R E C I T A L

     Mr. Frenzel and Centaur desire to modify the employment relationship
between them and provide for certain other matters on the terms and subject to
the conditions described in this Agreement.

     N O W,  T H E R E F O R E, the parties hereto hereby agree as follows:

     1.   Mr. Frenzel and Centaur agree that Mr. Frenzel hereby resigns from all
positions he now holds with Centaur, including the positions of President, Chief
Executive Officer, and a Director, effective on January 1, 2000 (the "Transition
                                                                      ----------
Date").
----

     2.   From the Transition Date through December 31, 2000, Mr. Frenzel will
be a part-time employee of Centaur, and will be responsible for specific tasks
to be designated by the Chairman of the Board of Centaur.  Mr. Frenzel's new
title will be "Advisor," and he will report to the Chairman of the Board.  Mr.
Frenzel's time commitment to Centaur will be a maximum of half-time during this
period on average.  During this period, Mr. Frenzel will be provided an office,
phones, supplies, computer and support services, and the like in Centaur's
Memorex Drive facility.  The number of hours of service to be provided to
Centaur by Mr. Frenzel shall be in Centaur's discretion; provided that the
number of hours does not exceed the maximum set forth above.

     3.   Subject to Section 4, Mr. Frenzel will retain his current full salary
and benefits until December 31, 2000.  Centaur will pay Mr. Frenzel in the
ordinary course on its regular payroll dates through December 31, 2000.  Each
payment shall consist of $10,707.42 less applicable deductions.  On January 1,
2001, the two personal computer that Mr. Frenzel used as of December 31, 1999
will become his personal property.  Mr. Frenzel acknowledges that he is not
entitled to any other payments or amounts from Centaur, except that Centaur (i)
will reimburse him for reasonable business expenses incurred in the ordinary
course of carrying out his duties in accordance with Centaur's standard
reimbursement policies, and (ii) will pay him for any accrued but unused
vacation time upon termination of his employment on December 31, 2000.

     4.   If Mr. Frenzel accepts consulting work (whether paid or unpaid) or
part or full time employment (whether paid or unpaid) from a third party before
December 31, 2000, and Centaur reasonably determines that these activities
create a direct, competitive conflict with the business of Centaur, then the
second six months of salary (or a pro rata portion thereof, if such consulting
work or employment occurs after June 30, 2000) will not be payable and Mr.
Frenzel will be released from future employment or consulting obligations to
Centaur pursuant to Section 2, 3 and 6.  For the purposes of this provision, a
direct, competitive conflict shall mean Mr. Frenzel's working with a
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company using a technology substantially similar to that of Centaur to pursue
applications substantially similar to those pursued by Centaur.

     5.   Mr. Frenzel currently holds stock options to purchase 164,350 shares
of Centaur's Common Stock. These stock options will continue to vest
uninterrupted until December 31, 2000 and will continue to be treated as
incentive stock options to the extent permitted by law. Thereafter, all unvested
stock options will continue to vest on the same schedule as is currently in
place during the period of Mr. Frenzel's consultancy described below, but shall
be characterized as non-qualified stock options. Mr. Frenzel acknowledges that
he does not currently have, nor does he have any other rights to acquire, any
other stock or other equity interest of Centaur. Mr. Frenzel also acknowledges
that to the extent that his stock options are incentive stock options, they must
be exercised within 90 days of the termination of his employment to retain such
status.

     6.   For the period of January 1, 2001 to December 31, 2003, Mr. Frenzel
will become a consultant to Centaur, and will advise Centaur as requested by the
Chairman of the Board, on issues of importance to Centaur.  The time allotted to
these tasks will be determined by mutual agreement between Mr. Frenzel and
Centaur, and the parties acknowledge that there is no understanding that Mr.
Frenzel will be available, or that Centaur will utilize Mr. Frenzel for any
minimum period of time.  For his consulting time, Mr. Frenzel will be paid
$1,000 per day (or $125 per hour for partial days).  When his consulting duties
require it, Mr. Frenzel will also have access to office and support services at
Centaur.  Centaur will reimburse Mr. Frenzel for reasonable business expenses
incurred in the ordinary course of carrying out his duties in accordance with
Centaur's standard reimbursement policies.  As a consultant, Mr. Frenzel shall
be an independent contractor and shall be responsible for and pay all taxes
applicable to any amounts he receives from Centaur as a consultant.  As a
consultant, Mr. Frenzel shall undertake such tasks as are requested by Centaur
and the confidentiality and invention assignment provisions of Mr. Frenzel's
Confidentiality Agreement (describe below) shall apply to his work as a
consultant.

     7.   At any time at the request of Centaur, Mr. Frenzel agrees that he will
identify to Centaur and turn over to Centaur all files, memoranda, records (and
copies thereof), credit cards, computer disks and other property in Mr.
Frenzel's possession that are the property of Centaur.  Mr. Frenzel further
acknowledges that he has previously entered into an Employee Invention
Assignment and Confidentiality Agreement effective December 1, 1993 (the
"Confidentiality Agreement") with Centaur, that various provisions thereof are
 -------------------------
intended to survive the modification and termination of his employment
relationship with Centaur, including, without limitation, the provisions of
Sections 6 (Assistance re: Inventions), 8 (Confidentiality) and 11 (Non-
Solicitation), and that Mr. Frenzel will abide by all such obligations.

     8.   Centaur and Mr. Frenzel each agree not to disparage the other.  They
also agree to keep the terms and conditions of this Agreement confidential,
other than as is necessary for purposes of compliance with law, including tax
and securities law disclosures, seeking legal or accounting advice, or
enforcement of this Agreement.

     9.   EXCEPT FOR THE AGREEMENTS SET FORTH HEREIN, INCLUDING THE CONTINUING
OBLIGATIONS OF MR. FRENZEL UNDER THE CONFIDENTIALITY AGREEMENT, EACH PARTY TO
THIS AGREEMENT HEREBY FOREVER RELEASES AND
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DISCHARGES THE OTHER, ITS SUCCESSORS, SUBSIDIARIES, HEIRS, EMPLOYEES,
STOCKHOLDERS, OFFICERS, DIRECTORS AND AGENTS, FROM ANY AND ALL CLAIMS,
LIABILITIES, EXPENSES, DAMAGES, DEMANDS AND CAUSES OF ACTION, KNOWN OR UNKNOWN,
FIXED OR CONTINGENT, WHICH SUCH PARTY HAS OR MAY HEREAFTER HAVE ARISING OUT OF
OR IN ANY WAY CONNECTED WITH MR. FRENZEL'S EMPLOYMENT OR OTHER RELATIONSHIP WITH
CENTAUR, INCLUDING THE RESIGNATION OF HIS ROLES AS PRESIDENT, CEO, AND A
DIRECTOR OF CENTAUR, THROUGH THE DATE HEREOF.

     10.  The parties further agree that, upon Centaur's request provided at any
time after January 1, 2000 (which request may be made on more than one occasion)
and with the consent of Mr. Frenzel, Centaur and Mr. Frenzel will enter into a
Release Addendum in the form attached hereto as Exhibit A for the purpose of
                                                ---------
extending the effective date of the release set forth herein.  If Mr. Frenzel
refuses to consent then Centaur may, at its option, terminate this Agreement and
/or unvest 80% of any options held by Mr. Frenzel that have vested since the
date of the most recent release provided by Mr. Frenzel pursuant to this
Agreement, such that those options will not be exercisable by Mr. Frenzel (or to
repurchase at cost any of such options that have been exercised by Mr. Frenzel);
provided that under no circumstances may Centaur unvest or repurchase any option
or shares that have vested as of January 1, 2000.

     11.  Mr. Frenzel understands and agrees that in consideration of the
foregoing, any current or future rights to pursue any and all remedies available
in any state or other jurisdiction under any employment or other Centaur-related
causes of action, are hereby waived, including without limitation:

          (a)  claims of wrongful discharge, defamation, emotional distress,
breach of contract, breach of the covenant of good faith and fair dealing; and

          (b)  claims under the Age Discrimination in Employment Act of 1967, as
amended; Title VII of the 1964 Civil Rights Act, as amended; the Equal Pay Act
of 1963, as amended; the Civil Rights Act of 1866, as amended; and any other
laws and regulations relating to employment discrimination.

Notwithstanding any provisions in this Agreement to the contrary, the releases
given under this Agreement shall not extend to any rights, claims or causes of
action currently unknown to Mr. Frenzel to the extent hereafter arising with
respect to Mr. Frenzel's rights regarding future medical benefits arising under
COBRA.


     12.  Each party to this Agreement expressly acknowledges that the releases
set forth above are intended to apply to both known and unknown claims, causes
of action, etc., and accordingly each party agrees that:

          Each party expressly waives any right or benefit available to him in
any capacity under the provisions of section 1542 of the Civil Code of
California, which provides:

          "A RELEASE DOES NOT EXTEND TO CLAIMS WHICH THE CREDITOR DOES NOT KNOW
          OR SUSPECT TO EXIST IN HIS FAVOR AT THE TIME OF
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          EXECUTING THE RELEASE, WHICH IF KNOWN BY HIM MUST HAVE MATERIALLY
          AFFECTED HIS SETTLEMENT WITH THE DEBTOR."

     13.  Mr. Frenzel hereby acknowledges that he has read and understands the
releases set forth in Sections 9 through 12 above (collectively, the "Release")
                                                                      -------
and has executed this Agreement voluntarily and without coercion.  Mr. Frenzel
further acknowledges that he was given 21 days within which to consider the
Release; that he was advised by Centaur to consult with an attorney of his own
choosing concerning the waivers contained in the Release; that he has done so or
has had the opportunity to do so and that the waivers made herein are knowing,
conscious and with full appreciation that he is forever foreclosed from pursuing
any of the rights so waived.  Mr. Frenzel further acknowledges that the
financial and other terms of this Agreement are consideration for the Release.

          Mr. Frenzel understands that for a period of seven days after signing
the Release he has the right to revoke it and that this Agreement, including but
not limited to the Release, shall not become effective or enforceable until
after those seven days.

     14.  The Indemnification Agreement entered into between Mr. Frenzel and
Centaur will continue in full force and effect to Mr. Frenzel's role as Advisor
and consultant to Centaur.

     15.  Mr. Frenzel represents and acknowledges that he has carefully read and
fully understands all of the provisions of this Agreement, which sets forth the
entire agreement between the parties.  This Agreement supersedes any and all
prior agreements or understandings between the parties, including, but not
limited to, all corporate policies, practices or procedures pertaining to the
subject matter of this Agreement.  Mr. Frenzel represents that he has full
authority to enter into this Agreement and that no other person has any claim or
interest in the matters described herein, and that this Agreement is binding on
himself, his estate, heirs and assigns.

     16.  Mr. Frenzel understands and agrees that in the event of a breach of
his confidentiality or non-solicitation obligations under this Agreement and/or
the Confidentiality Agreement Centaur may suffer irreparable harm and will
therefore be entitled to injunctive relief to enforce this Agreement and the
Confidentiality Agreement.

     17.  This Agreement will be governed and interpreted in accordance with the
internal laws of the State of California, excluding that body of law governing
conflicts of law.

     18.  If one or more provisions of this Agreement or the Confidentiality
Agreement are held to be unenforceable under applicable law, such provision
shall be enforced to the maximum extent permitted by law, and the balance of
this Agreement and the Confidentiality Agreement shall remain in full force and
effect and shall be interpreted so as to effect the intent of the parties.

     19.  Any term of this Agreement may be amended and the observance of any
term of this Agreement may be waived only with the written consent of Centaur
and Mr. Frenzel.


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PLEASE READ CAREFULLY.  THIS AGREEMENT INCLUDES A RELEASE OF ALL KNOWN AND
UNKNOWN CLAIMS.

          Executed at Sunnyvale, California this 6th day of June 2000.

                              BRIAN FRENZEL


                              By  /s/ Brian Frenzel
                                  --------------------------------------
                                    Brian Frenzel

                              (You may sign on any date not more than 25 days
                              after June 1, 2000 the date that Centaur presents
                              you with this Agreement.)

          Executed at Sunnyvale, California this 1st day of June 2000.

                              CENTAUR PHARMACEUTICALS, INC.


                              By: /s/ Charles R. Engles
                                  --------------------------------------
                                  Charles R. Engles, Acting Chief Operating
                                  Officer






            [Signature page of Employment and Consulting Agreement]
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                               RELEASE ADDENDUM



          Centaur Pharmaceuticals, Inc. ("Centaur") and Brian Frenzel ("Mr.
Frenzel") hereby agree that the Release set forth in Section 9 of that certain
Employment and Consulting Agreement dated January 1, 2000 (the "Agreement")
shall apply to matters occurring on or before June 1, 2000. To implement the
foregoing, it is agreed that the last four words of Section 9 are hereby amended
to read "through June 1, 2000". All other provisions of the Agreement remain in
full force and effect and apply to this Release Addendum, including, without
limitation, Section 13 of the Agreement.

CENTAUR PHARMACEUTICALS, INC.


By:  /s/ Charles R. Engles                        /s/ Brian Frenzel
     --------------------------------------       ------------------------------
     Name:  Charles R. Engles                     Brian Frenzel
     Title:  Acting Chief Operating Officer

Date:     June 1, 2000                            Date:     June 6, 2000
     --------------------------------------             ------------------------
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                                   Exhibit A

                               RELEASE ADDENDUM



     Centaur Pharmaceuticals, Inc. ("Centaur") and Brian Frenzel ("Mr. Frenzel")
hereby agree that the Release set forth in Section 9 of that certain Employment
and Consulting Agreement dated January 1, 2000 (the "Agreement") shall apply to
matters occurring on or before December 31, 2000 [or any later date requested by
Centaur], the last day of Mr. Frenzel's employment with Centaur.  To implement
the foregoing, it is agreed that the last four words of Section 9 are hereby
amended to read "through December 31, 2000 [or any later date requested by
Centaur]".  All other provisions of the Agreement remain in full force and
effect and apply to this Release Addendum, including, without limitation,
Section 13 of the Agreement.

CENTAUR PHARMACEUTICALS, INC.


By:  _______________________________         ___________________________________
     Name:                                   Brian Frenzel
     Title:

Date:_______________________________         Date:______________________________