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                                                                EXHIBIT 10.64
                                                                Page 1 of 5


                   AMENDMENT NO. 1 TO 1516 SANTA ANITA LEASE

    THIS AMENDMENT NO. 1 TO 1516 SANTA ANITA LEASE ("AMENDMENT NO. 1") is
made and entered as of May 25, 2000 ("EFFECTIVE DATE"), by and between ART
WEISS, INC., a California corporation ("LESSOR"), and LEE PHARMACEUTICALS, a
California corporation ("LESSEE").


                                   RECITALS

    A. Lessor and Lessee are parties to that certain Standard Industrial
Lease - Gross dated April 16, 1990 (the "LEASE"), pursuant to which Lessee
leased from Lessor approximately 17,600 square feet in that certain concrete
block one story office and factory building located at 1516 Santa Anita
Avenue in South El Monte, California (the "PREMISES").

    B. Lessor and Lessee are also parties to that certain Settlement
Agreement of even date herewith ("SETTLEMENT AGREEMENT"). In order to settle
the Disputes referenced in the Settlement Agreement, Lessor and Lessee agreed
to amend this Lease on the terms and conditions set forth below. Capitalized
terms not otherwise defined in this Amendment No. 1 shall have the same
meaning as set forth in the Lease or in the Settlement Agreement, as
applicable.

    NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein contained, and other good and valuable consideration, the parties do
hereby agree as follows:

    1. RECITALS. The foregoing Recitals are incorporated by reference as if
fully set forth herein, and the terms and provisions of the Settlement
Agreement are specifically incorporated herein by reference as if fully set
forth herein.

    2. AMENDMENTS TO LEASE. The Lease is hereby amended as follows:

       a. EXERCISE OF FIRST OPTION TO EXTEND TERM. Lessee hereby exercises
it's option to extend the term of this Lease from December 1, 2000 up to and
including November 30, 2005 ("FIRST EXTENSION PERIOD"). Lessor hereby accepts
said exercise.

       b. PARAGRAPH 4 - RENT. Paragraph 4 is hereby deleted in its entirety
and replaced with the following new Paragraph 4:

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"4. RENT

    4.1  MONTHLY BASE RENT. Lessee agrees to and shall pay to Lessor monthly
base rent for the Premises for the following periods (inclusive of the First
Extension Period) in the amounts set forth below. Lessee shall pay Lessor
each payment of monthly base rent, in advance, on the first (1st) day of each
month during each period of the term of this Lease:

         PERIOD                               MONTHLY BASE RENT
         ------                               -----------------

    (a)  MARCH 1, 2000 - NOVEMBER 30, 2000:   $7,744.00 per month

    (b)  DECEMBER 1, 2000 - NOVEMBER 30, 2002:  On December 1, 2000, the monthly
         base rent under the Lease in effect as of November 30, 2000 shall be
         multiplied by a fraction, the numerator of which is the Consumer
         Price Index Los Angeles-Riverside-Orange County (All Items - All
         Urban Consumers)(1982-84 = 100)(the "INDEX") for December, 2000, and
         the denominator of which shall be 163.5 (which was the Index for
         December, 1998). The amount so calculated shall constitute the new
         monthly base rent for the period December 1, 2000 through November
         30, 2002, provided, however, in no event shall the new monthly base
         rent for said period be less than the monthly base rent payable during
         November, 2000.

    (c)  DECEMBER 1, 2002 - NOVEMBER 30, 2004:  On December 1, 2002, the
         monthly base rent in effect as of November 30, 2002 shall be
         multiplied by a fraction, the numerator of which is the Index for
         December, 2002, and the denominator of which shall be the Index for
         December, 2000. The amount so calculated shall constitute the new
         monthly base rent for the period December 1, 2002 through November 30,
         2004, provided, however, in no event shall the new monthly base rent
         be less than the monthly base rent payable during November, 2002.

    (d)  DECEMBER 1, 2004 - NOVEMBER 30, 2005:  On December 1, 2004, the
         monthly base rent in effect as of November 30, 2004 shall be multiplied
         by a fraction, the numerator of which is the Index for December,
         2004, and the denominator of which shall be the Index for December,
         2002. The amount so calculated shall constitute the new monthly base
         rent for the period December 1, 2004 through November 30, 2005,
         provided, however, in no event shall the new monthly base rent be
         less than the monthly base rent payable during November, 2004.

    (e)  ADJUSTMENTS PENDING RECEIPT OF FINAL INDEX.  For each of the
         adjustment dates referenced above, pending receipt of the required
         Index Lessee shall pay Lessor an estimated adjusted monthly base
         rent, reasonably determined by the Lessor based on the then available
         Index information. Upon notification of the actual adjustment after
         publication of the required


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                                                              Page 3 of 5

         Index, Lessee shall be credited with any overpayments against the
         next due monthly base rent, or if applicable Lessee shall pay Lessor
         any underpayments with the next due monthly base rent."

    4.2  NEGOTIATED RENT FOR SPECIFIED PERIODS. In addition to the monthly
base rent referenced in PARAGRAPH 4.1 above, Lessee shall also pay to Lessor
the following amounts of additional "NEGOTIATED RENT" for the Premises for
the following periods. Each payment of Negotiated Rent shall be due and
payable, in advance, on the first (1st) day of the month for the period
specified:

         PERIOD                                 NEGOTIATED RENT
         ------                                 ---------------

         March 1, 2001 - March 31, 2001:          $5,000.00
         April 1, 2001 - April 30, 2001:          $5,000.00
         May 1, 2001 - May 31, 2001:              $5,000.00"

    c.   GRANT OF SECOND OPTION TO EXTEND TERM. Lessee is hereby granted the
conditional right and option ("SECOND OPTION TO EXTEND") to extend the term
of this Lease for a single additional period of five (5) consecutive years
(the "SECOND EXTENSION PERIOD"), on the same terms and conditions in effect
under this Lease immediately prior to commencement of the Second Extension
Period, except that monthly base rent shall be increased to the Second
Extension Period Monthly Base Rent (defined below). If the Second Option to
Extend is timely exercised, then the Second Extension Period shall commence
on December 1, 2005 and shall terminate on November 30, 2010. Lessee shall
have no further rights or options to extend the term of this Lease. The
Second Option to Extend is personal to Lessee, may only be exercised by
Lessee, and may be exercised only by Lessee delivering to Lessor irrevocable
and unconditional written notice thereof ("NOTICE OF EXERCISE OF SECOND
OPTION") not less than one hundred eighty (180) calendar days and not more
than three hundred sixty (360) calendar days prior to commencement of the
Second Extension Period. If Lessee for any reason fails to timely exercise
the Second Option to Extend on the terms and conditions set forth above, then
the Second Option to Extend shall terminate, expire and have no further force
or effect. Further, if Lessee for any reason fails to timely make any payment
of Negotiated Rent pursuant to this Lease in good and drawable funds on (or
before, at Lessee's option) the date when due, or if Lessee fails to timely
make any payment of Negotiated Rent to any other Lessor under any of the
other Leases (as those terms are defined in the Settlement Agreement) in good
and drawable funds on (or before, at Lessee's option) the date when due, then
in each instance and without further notice the Second Option to Extend under
this Lease shall automatically terminate, expire and have no further force or
effect. For purposes of this Lease, the phrase "SECOND EXTENSION PERIOD
MONTHLY BASE RENT" shall mean as follows:

         (i)  DECEMBER 1, 2005 THROUGH NOVEMBER 30, 2007. At commencement of
the Second Extension Period, the monthly base rent under this Lease in effect
as of November 30, 2005 shall be multiplied by a fraction, the numerator of
which is the Index for December, 2005, and the denominator of which shall be
the Index for December, 2003. The amount so calculated shall constitute the
new monthly base rent for the period December 1, 2005


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through November 30, 2007, provided, however, in no event shall the new
monthly base rent for said period be less than the monthly base rent payable
during November, 2005.

         (ii) DECEMBER 1, 2007 THROUGH NOVEMBER 30, 2009. On December 1,
2007, the monthly base rent in effect as of November 30, 2007 shall be
multiplied by a fraction, the numerator of which is the Index for December,
2007, and the denominator of which shall be the Index for December, 2005. The
amount so calculated shall constitute the new monthly base rent for the
period December 1, 2007 through November 30, 2009, provided, however, in no
event shall the new monthly base rent be less than the monthly base rent
payable during November, 2007.

         (iii) DECEMBER 1, 2009 THROUGH NOVEMBER 30, 2010. On December 1,
2009, the monthly base rent in effect as of November 30, 2009 shall be
multiplied by a fraction, the numerator of which is the Index for December,
2009, and the denominator of which shall be the Index for December, 2007. The
amount so calculated shall constitute the new monthly base rent for the
period December 1, 2009 through November 30, 2010, provided, however, in no
event shall the new monthly base rent be less than the monthly base rent
payable during November, 2009.

         (iv) ADJUSTMENTS PENDING RECEIPT OF FINAL INDEX. For each of the
adjustment dates referenced above, pending receipt of the required Index
Lessee shall pay Lessor an estimated adjusted monthly base rent, reasonably
determined by the Lessor based on the then available Index information. Upon
notification of the actual adjustment after publication of the required
Index, Lessee shall be credited with any overpayments against the next due
monthly base rent, or if applicable Lessee shall pay Lessor any underpayments
with the next due monthly base rent.

         (v)  SECOND OPTION TO EXTEND IS PERSONAL TO LESSEE. Lessee's
exercise of the Second Option to Extend Term shall not operate to cure any
default by Lessee of any of the terms or provisions in this Lease, nor to
extinguish or impair any rights or remedies of Lessor arising by virtue of
such default. If this Lease, any term hereof or Lessee's right to possession
of the Premises shall terminate in any manner whatsoever before Lessee
exercises the Second Option to Extend, or if Lessee shall have subleased or
assigned all or any portion of the Premises without Lessor's prior written
consent, then immediately upon such termination, sublease or assignment, the
Second Option to Extend shall simultaneously terminate and become null and
void. The Second Option to Extend is personal to Lessee. In no circumstance
shall the assignee under a complete or partial assignment of this Lease, or a
subtenant under a sublease of all or any portion of the Premises, have the
right to exercise the Second Option to Extend. Unless Lessor otherwise agrees
in writing, any purported assignment of the Lease by Lessee or any purported
sublease by Lessee of any part of the Premises after the date Lessee
purportedly exercised the Second Options to Extend and before commencement of
the Second Extension Period shall automatically and retroactively cause said
exercise to become null and void and of no force or effect, in which event
the term of this Lease shall terminate and expire on November 30, 2005. Time
is of the essence of this provision.


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                                                              Page 5 of 5

    3. WHOLE AGREEMENT. This Amendment No. 1 and the Settlement Agreement
together set forth the entire agreement between the parties with respect to
the matters set forth herein. There have been no additional oral or written
representations or agreements concerning the Premises or the Lease. As
amended herein, the Lease shall remain in full force and effect. In case of
any inconsistency between the provisions of the Lease and this Amendment No.
1, the provisions of this Amendment No. 1 shall govern and control; and in
case of any inconsistency between the provisions of this Lease (as amended)
and the Settlement Agreement, the provisions of the Settlement Agreement
shall govern and control.

    IN WITNESS WHEREOF, the Lessor and Lessee have duly executed this
Amendment No. 1 as of the date set forth below, in South El Monte,
California. Notwithstanding the actual date of execution, this Amendment No.
1 shall for all purposes be deemed effective as of the Effective Date first
above written.

LESSOR                        LESSEE

ART WEISS, INC., a            LEE PHARMACEUTICALS, INC., a
California corporation,       California corporation,


By: /s/ Art Weiss             By: /s/ Ronald G. Lee
   -------------------          ---------------------
    Art Weiss, President        Ronald G. Lee, President


Date:  5-22-2000              Date: 5/24/00
    -------------------          ---------------------



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