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                                                                   Exhibit 10.11
                            FIRST AMENDMENT TO THE
                    PATENT AND TRADEMARK SECURITY AGREEMENT


     THIS FIRST AMENDMENT TO THE PATENT AND TRADEMARK SECURITY AGREEMENT, dated
as of June 20, 2001 (this "Amendment"), by and between SENETEK, plc, a
                           ---------
corporation organized under the laws of England (the "Company") and each of the
                                                      -------
undersigned (each a "Grantor", and collectively with the Company, the
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"Grantors") and SILVER CREEK INVESTMENTS, LTD., a British Virgin Islands
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company, as Collateral Agent (the "Collateral Agent") for the benefit of the
                                   ----------------
purchasers (the "Original Purchasers") set forth on Schedule 1 of the Original
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Purchase Agreement (as defined below) and the Lender (as defined below).

     WHEREAS, the Company and the Original Purchasers have entered into a
Securities Purchase Agreement dated as of April 14, 1999 (the "Original Purchase
                                                               -----------------
Agreement");
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     WHEREAS, as collateral security for payment and performance of its
Obligations (as defined in the Original Purchase Agreement), each of the
Grantors granted to the Original Purchasers a security interest in all of its
patents and trademarks pursuant to the terms of the Patent and Trademark
Security Agreement by and among the Grantors and the Collateral Agent (as the
same from time to time may be amended, modified, supplemented, extended or
restated, the "Patent and Trademark Security Agreement");
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     WHEREAS, Wallington Investments Limited, a corporation organized under the
laws of the British Virgin Islands (the "Lender"), has agreed to extend certain
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financial accommodations to the Company in connection with the financing of the
working capital needs of the Company, and Lender is willing to extend such
financial accommodations to the Company pursuant to the terms of a Revolving
Credit Agreement to be entered into by the Company and Lender (the "Credit
                                                                    ------
Agreement");
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     WHEREAS, as a condition to Lender entering into the Credit Agreement and
extending financial accommodations to the Company thereunder, and in
consideration thereof, the Company and the Original Purchasers are (i) entering
into a First Amendment to the Purchase Agreement dated the date hereof (the
"First Amendment"; the Original Purchase Agreement, as amended by the First
 ---------------
Amendment is referred to herein as the "Purchase Agreement") in order to modify
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certain terms of the Original Purchase Agreement to, among other things, permit
the Company to enter into the Credit Agreement and (ii) amending certain of the
Transaction Documents, including, without limitation, the Patent and Trademark
Security Agreement, to include the Lender as a secured party thereunder.
Capitalized terms used but not otherwise defined herein shall have the meaning
set forth in the Purchase Agreement;
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     WHEREAS, the Lender is unwilling to enter into the Credit Agreement unless
the Grantors and the Collateral Agent on behalf of the Original Purchasers and
the Lender enter into this Amendment;

     NOW, THEREFORE, in consideration of the mutual promises hereinafter set
forth and for other good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, the parties hereto, intending to be legally
bound hereby, do hereby agree as follows:

     1.   Amendments to the Patent and Trademark Security Agreement. (a) The
          ---------------------------------------------------------
heading of the Patent and Trademark Security Agreement shall be amended and
restated to read as follows:

          "THIS PATENT AND TRADEMARK SECURITY AGREEMENT, dated as of April 14,
     1999, as amended by the First Amendment dated June 20, 2001 (this
     "Agreement"), is made by and between SENETEK, plc, a corporation organized
     under the laws of England (the "Company") and each of the undersigned (each
                                     -------
     a "Grantor", and collectively with the Company, the "Grantors") and SILVER
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     CREEK INVESTMENTS, LTD., a British Virgin Islands company, as Collateral
     Agent (the "Collateral Agent") for the benefit of the purchasers (the
                 ----------------
     "Original Purchasers") set forth on Schedule 1 of the Purchase Agreement
     --------------------                ----------
     (as defined below) and Wallington Investments Limited, a company organized
     under the laws of the British Virgin Islands (the "Lender").
                                                        ------

          (b)  The fourth "WHEREAS" clause of the Patent and Trademark Security
Agreement is hereby amended and restated in its entirety as follows:

          "WHEREAS, as collateral security for payment and performance of: (i)
     the Company's Obligations under the Purchase Agreement, the Credit
     Agreement, the Lender's Note and any and all related documents; and (ii)
     the Guarantors' Obligations (as defined in the Guaranty (as such Guaranty
     is amended by the First Amendment to the Guaranty dated the date hereof
     from the Guarantors (as defined therein) for the benefit of the Collateral
     Agent (on behalf of the Original Purchasers and the Lender), and as such
     Guaranty is further amended from time to time) (the "Secured Obligations");
                                                          -------------------
     and the Grantors are each willing to grant to the Collateral Agent for the
     benefit of the Purchasers a security interest in all of its patents and
     trademarks; and"

          (c)  Section 1(a) of the Patent and Trademark Security Agreement is
hereby amended and restated in its entirety as follows:

          "Unless otherwise defined herein, each capitalized term used herein
     that is defined in the Purchase Agreement shall have the meaning specified
     for such term in the Purchase Agreement, except that (i) the term

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     "Purchasers" as used herein shall in all cases be deemed to include both
     the Original Purchasers and the Lender and (ii) the term "Event of Default"
     as used herein shall in all cases be deemed to include both an Event of
     Default (as defined in the Purchase Agreement) and (ii) an Event of Default
     (as defined in the Credit Agreement)."

     2.   Conditions to Effectiveness.  This Amendment shall become effective
          ---------------------------
only upon the satisfaction or waiver of all of the following conditions
precedent:

     (a)  The parties hereto shall have duly executed and delivered this
Amendment.

     (b)  The Company shall have satisfied all conditions to effectiveness under
Section 6 of the First Amendment.

     (c)  The Company shall have paid all fees and expenses required to be paid
by it pursuant to Section 5 of the First Amendment.

     3.   Representations and Warranties.  In order to induce the Collateral
          ------------------------------
Agent to enter into this Amendment (on behalf of the Original Purchasers and the
Lender), each Grantor hereby represents and warrants to the Original Purchasers
and the Lender that it has full power, right and legal authority to execute,
deliver and perform its obligations under this Amendment.  Each Grantor has
taken all corporate action necessary to authorize the execution and delivery of,
and the performance of its obligations under, this Amendment.  This Amendment
constitutes a legal, valid and binding obligation of each Grantor enforceable
against it in accordance with its terms, subject to the effect of any applicable
bankruptcy, insolvency, reorganization or moratorium or similar laws affecting
the rights of creditors generally. Each Grantor hereby ratifies and reaffirms
the Patent and Trademark Security Agreement (as amended hereby) and the other
related documents and each of its respective covenants, duties and liabilities
thereunder.

     4.   U.S. Patent Office Filing.  The Grantors acknowledge that this
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Amendment shall be filed with the U.S. Patent Office and, at the sole discretion
of the Collateral Agent, may be filed in any other corresponding offices in
other countries and foreign jurisdictions through out the world.  Each Grantor
shall, in accordance with Section 16 and 21 of the Patent and Trademark
Agreement, pay all costs incurred by the Collateral Agent (on behalf of the
Original Purchasers and the Lender) with respect to this Amendment, including
without limitation, the cost of such filings and shall at its own expense do
such further acts and things, and to execute and deliver such additional
conveyances, assignments, financing statements, agreements and instruments, as
the Collateral Agent for the benefit of the Original Purchasers and the Lenders
may at any time reasonably request in connection with the administration or
enforcement of this Agreement.

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     5.   Amendments. This Amendment may not be amended, modified or
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supplemented except by a subsequent written agreement signed by the parties
hereto.

     6.   Counterparts. This Amendment may be executed simultaneously in any
          ------------
number of counterparts.  Each counterpart shall be deemed to be an original, and
all such counterparts shall constitute one in the same instrument.

     7.   Governing Law.  This Amendment shall be governed by the laws of the
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State of New York (without giving effect to any conflicts of law rules or
principles).

     8    Headings.   The headings of this Amendment are included herein for
          --------
convenience of reference only and shall not constitute a part of this Amendment
for any other purpose.

     9.   Survival of the Security Agreement.  Each reference in the Patent and
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Trademark Security Agreement to "this Agreement," "hereunder," "hereof,"
"herein" or words of like import, and each reference to the Patent and Trademark
Security Agreement in any related document (other than the Patent and Trademark
Security Agreement) shall mean and be a reference to the Patent and Trademark
Security Agreement as amended hereby. Except as specifically amended by this
Amendment, the Patent and Trademark Security Agreement shall remain in full
force and effect and is hereby ratified, confirmed and acknowledged by each of
the Grantors. This Amendment shall not be deemed to (i) be a consent to any
waiver or modification of any term or condition of the Patent and Trademark
Security Agreement or any document delivered pursuant thereto, except in each
case as expressly provided herein, or (ii) prejudice any right or rights the
Original Purchasers or the Lender may now or in the future have in connection
with the Patent and Trademark Security Agreement.


      [Signature page follows, remainder of page is intentionally blank]

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          IN WITNESS WHEREOF, the parties hereto have duly executed this First
Amendment to the Patent and Trademark Security Agreement as of the day and year
first above written.

                              GRANTORS:
                              --------

                              SENETEK, PLC


                              By: /s/ Frank J. Massino
                                  --------------------
                                  Name: Frank J. Massino
                                  Title: President


                              CARME COSMECEUTICAL SCIENCES, INC.


                              By: /s/ Frank J. Massino
                                  --------------------
                                  Name: Frank J. Massino
                                  Title: President


                              SECURED PARTY:
                              -------------

                              SILVER CREEK INVESTMENTS, LTD.


                              By: /s/ Robert T. Tucker
                                  ---------------------
                                  Name: Robert T. Tucker
                                  Title: Director



  [Signature page to the First Amendment to the Patent and Trademark Security
                                  Agreement]