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                                                                   EXHIBIT 10.21

          AMENDMENT NUMBER 1 TO MASTER LEASE AND FINANCING AGREEMENT

     THIS AMENDMENT NUMBER 1 TO MASTER LEASE AND FINANCING AGREEMENT (this
"Amendment") is dated as of this ____ day of January, 2000, by and between
Compaq Financial Services Corporation, a Delaware corporation ("Lessor"), and
AltaVista Company, a Delaware corporation ("Lessee").

                                  WITNESSETH:
WHEREAS:

     A.  Lessor and Lessee have entered into that certain Master Lease and
Financing Agreement Number 100749 dated November 24, 1999 (the "Master
Agreement") pursuant to which Lessor is willing to purchase and lease to Lessee,
certain equipment listed on Schedules thereto executed by Lessor and Lessee from
time to time. Capitalized terms used in this Amendment without definition have
the meanings assigned to them in the Master Agreement to which this Amendment is
attached and hereby made part thereof.

     B.  Lessee has requested, and Lessor has agreed to, certain modifications
to the Master Agreement.

     C.  The parties are entering into this Amendment for the purposes of
effecting such modifications.

     NOW, THEREFORE, for good and valuable consideration the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

1.   Modifications to Master Agreement.
     ----------------------------------

     (A)  Exhibit A.

          The last sentence of Section 3 shall be deleted.

     (B)  Exhibit B.

          (a)  The last sentence of Section 4 shall be deleted.
          (b)  The last sentence of Section 5 shall be deleted.

     (C)  Exhibit C.

          The last sentence of Section 4 shall be deleted.

(2)  Definitions.  Unless otherwise defined herein, words and expressions
     -----------
     defined in the Master Agreement, as amended hereby, shall bear the same
     meanings when used herein.

(3)  No Other Amendment.  All other terms and conditions of the Master Agreement
     ------------------
     and any applicable Schedule shall remain in full force and effect and the
     Lease shall be read and construed as if the terms of this Amendment were
     included therein.
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(4)  GOVERNING LAW.  THIS AMENDMENT SHALL BE GOVERNED BY AND CONSTRUED IN
     -------------
     ACCORDANCE WITH THE LAWS OF THE STATE OF NEW JERSEY, WITHOUT REGARD TO
     CONFLICTS OF LAW PRINCIPLES.

     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed by their respective duly authorized officers, and delivered the day and
year first written above.

LESSEE:                               LESSOR:
ALTAVISTA COMPANY                     COMPAQ FINANCIAL SERVICES
                                        CORPORATION

By:__________________________         By:_____________________________
Name: _______________________         Name: __________________________
Title: ______________________         Title: _________________________EXHIBIT 4.3

                             ENTROPIN, INC.

          Incorporated Under the Laws of the State of Colorado

No. W-                                       _____ Common Stock
                                                   Purchase Warrants

                                                   CUSIP

                             CERTIFICATE FOR                 (See Reverse
                              COMMON STOCK                    For Certain
                            PURCHASE WARRANTS                Definitions)

     This Warrant Certificate certifies that ___________________, or
registered assigns ("the Warrant Holder"), is the registered owner of the
above indicated number of  Common Stock Purchase Warrants (the "Warrants")
expiring on __________________, 2005 (the "Expiration Date").  One Warrant
entitles the Warrant Holder to purchase one share of Common Stock ("Share")
from Entropin, Inc., a Colorado corporation (the "Company"), at a purchase
price of $___________ (the "Exercise Price"), commencing on ____________,
2000, and terminating on the Expiration Date ("Exercise Period"), upon
surrender of this Warrant Certificate with the exercise form hereon duly
completed and executed with payment of the Exercise Price at the office of
Corporate Stock Transfer, Inc. (the "Warrant Agent"), but only subject to
the conditions set forth herein and in a Warrant Agreement dated as of
___________, 2000 (the "Warrant Agreement") between the Company and the
Warrant Agent.  The Exercise Price, the number of shares purchasable upon
exercise of each Warrant, the number of Warrants outstanding and the
Expiration Date are subject to adjustments upon the occurrence of certain
events.  The Warrant Holder may exercise all or any number of Warrants.
Reference hereby is made to the provisions on the reverse side of this
Warrant Certificate and to the provisions of the Warrant Agreement, all of
which are incorporated by reference in and made a part of this Warrant
Certificate and shall for all purposes have the same effect as though fully
set forth at this place.

     Upon due presentment for transfer of this Warrant Certificate at the
office of the Warrant Agent, a new Warrant Certificate or Warrant
Certificates of like tenor and evidencing in the aggregate a like number of
Warrants, subject to any adjustments made in accordance with the provisions
of the Warrant Agreement, shall be issued to the transferee in exchange for
this Warrant Certificate, subject to the limitations provided in the
Warrant Agreement, upon payment of $_________ per Warrant Certificate and
any tax or governmental charge imposed in connection with such transfer.

     The Warrant Holder of the Warrants evidenced by this Warrant
Certificate may exercise all or any whole number of such Warrants during
the period and in the manner stated hereon.  The Exercise Price shall be
payable in lawful money of the United States of America and in cash or by
certified or bank cashier's check or bank draft payable to the order of the
Company.  If upon exercise

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of any Warrants evidenced by this Warrant Certificate the number of
Warrants exercised shall be less than the total number of Warrants so
evidenced, there shall be issued to the Warrant Holder a new Warrant
Certificate evidencing the number of Warrants not so exercised.

     Subject to the following paragraph, no Warrant may be exercised after
5:00 p.m. Mountain Time on the Expiration Date and any Warrant not
exercised by such time shall become void, unless extended by the Company.

     The Warrants are subject to redemption by the Company at $.25 per
Warrant, no earlier than ____________, 2001, at any time prior to their
expiration, or not less than 30 days' prior written notice to the holders
of Warrants, provided that the daily trading price per share of Common
Stock has been at least $___________ (200% of the Warrant exercise price)
for a period of at least 10 consecutive trading days ending within 5 days
prior to the date upon which the notice of redemption is given.  The
Warrant Holders shall have the right to exercise the Warrants held by them
before the date specified in the redemption notice.  Upon expiration of
such period, all rights of the Warrant Holders shall terminate, other than
the rights to receive the redemption price, without interest, and the right
to receive the redemption price shall itself expire on the Warrant
Expiration Date.

     This Warrant Certificate shall not be valid unless countersigned by
the Warrant Agent.

     IN WITNESS WHEREOF, the Company has caused this Warrant to be signed
by its President and by its Secretary, each by a facsimile of his/her
signature, and has caused a facsimile of its corporate seal to be imprinted
hereon.

     Dated:  ______________________

                                   ENTROPIN, INC.

_____________________________      By________________________________
Higgins D. Bailey, Secretary           Thomas G. Tachovsky, President

                                   CORPORATE STOCK TRANSFER, INC.
                                       Warrant Agent

                                   By_________________________________
                                       Carylyn K. Bell, President

                                   -2-

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                     FORM OF REVERSE SIDE OF WARRANT

     This Warrant Certificate, when surrendered to the Warrant Agent at its
principal office by the Warrant Holder, in person or by attorney duly
authorized in writing, may be exchanged in the manner and subject to the
limitations provided in the Warrant Agreement, upon the payment of any tax
or other governmental charge imposed in connection with such exchange, for
another Warrant Certificate or Warrant Certificates of like tenor and
evidencing a like number of Warrants, subject to any adjustments made in
accordance with the provisions of the Warrant Agreement.

     The Company and the Warrant Agent may deem and treat the registered
holder hereof as the absolute owner of this Warrant Certificate
(notwithstanding any notation of ownership or other writing hereon made by
anyone) for all proposes and neither the Company nor the Warrant Agent
shall be affected by any notice to the contrary.  No Warrant Holder, as
such, shall have any rights of a holder of the Common Stock of the Company,
either at law or at equity, and the rights of the Warrant holder, as such,
are limited to those rights expressly provided in the Warrant Agreement and
in the Warrant Certificate.

     Under the Warrant Agreement the Exercise Price is subject to
adjustment if the Company shall effect any stock split or stock combination
with respect to the Common Stock.  Any such adjustment of the Exercise
Price will also result in an adjustment of the number of shares of Common
Stock purchasable upon exercise of a Warrant or, if the Company should
elect, an adjustment of each outstanding Warrant into a different number of
Warrants.

     The Company shall not be required to issue fractions of Warrants upon
any such adjustment or to issue fractions of shares upon the exercise of
any Warrants upon any such adjustment, in accordance with the Warrant
Agreement.

     The Warrant Agreement is subject to amendment upon the approval of
holders of at least two-thirds of the outstanding Warrants as a group,
except that no such approval is required for the reduction of the Exercise
Price or extension of the Expiration Date.  No amendment shall accelerate
the Expiration Date or increase the Exercise Price without the approval of
all the holders of all outstanding Warrants.  A copy of the Warrant
Agreement will be available at all reasonable times at the office of the
Warrant Agent for inspection by any Warrant Holder.  As a condition of such
inspection, the Warrant Agent may require any Warrant Holder to submit the
Warrant Holder's Warrant Certificate for inspection.

IMPORTANT:  The Warrants represented by this Certificate may not be
exercised by a Warrant Holder unless at the time of exercise the underlying
shares of Common Stock are qualified for sale by registration or otherwise
in the state where the Warrant Holder resides or unless the issuance of the
shares of Common Stock would be exempt under the applicable state
securities laws.  Further, a registration statement under the Securities
Act of 1933, as amended, covering the issuance of shares of Common Stock
upon the exercise of this Warrant must be in effect and current at the time
of exercise unless the issuance of shares of Common Stock upon any exercise
is exempt from the registration requirements of the Securities Act of 1933.
Unless such registration statement is in effect and current at the time of
exercise, or unless such an exemption is available the Company may decline
to permit the exercise of this Warrant.

                                   -3-

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                  TRANSFER FEE $_____  PER CERTIFICATE

                             ENTROPIN, INC.

     The following abbreviations, when used in the inscription on the face
of this instrument, shall be construed as though they were written out in
full according to applicable laws or regulations:

TEN COM   - as tenants in common             UNIF GIFT MIN ACT -
TEN ENT   - as tenants by the entireties              Custodian
                                                    -------------
JT TEN    - as joint tenants with right      (Cust)      (Minor)
            of survivorship and not as       under Uniform Gifts
            tenants in common                to Minors Act _______
                                                           (State)

Additional abbreviations may also be used though not in the above list.

                           FORM OF ASSIGNMENT

    (To Be Executed by the Registered Holder if the Registered Holder
               Desires to Assign Warrants Evidenced by the
                       Within Warrant Certificate)

     FOR VALUE RECEIVED ______________________ hereby sells, assigns and
transfers unto __________________________ Warrants, evidenced by the within
Warrant Certificate, and does hereby irrevocably constitute and appoint
________________________ Attorney to transfer the said Warrants evidenced
by the within Warrant Certificate on the books of the Company, with full
power of substitution.

Dated: _________________           ________________________________
                                        Signature

NOTICE:   The above signature must correspond with the name as written upon
          the face of the within Warrant Certificate in every particular,
          without alteration or enlargement or any change whatsoever.

Signature Guaranteed:  _________________________________________

                                   -4-

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                      FORM OF ELECTION TO PURCHASE

    (To be Executed by the Holder if the Registered Holder Desires to
     Exercise Warrants Evidenced by the Within Warrant Certificate)

To Entropin, Inc.:

     The undersigned hereby irrevocably elects to exercise ________
Warrants, evidenced by the within Warrant Certificate for, and to purchase
thereunder, ____________________ full shares of Common Stock issuable upon
exercise of said Warrants and delivery of $_________ and any applicable
taxes.

     The undersigned requests that certificates for such shares be issued
in the name of:
                                   PLEASE INSERT SOCIAL SECURITY OR
                                        TAX IDENTIFICATION NUMBER

_______________________________    _________________________________
(Please print name and address)

_______________________________    _________________________________

_______________________________    _________________________________

     If said number of Warrants shall not be all the Warrants evidenced by
the within Warrant Certificate, the undersigned requests that a new Warrant
Certificate evidencing the Warrants not so exercised be issued in the name
of and delivered to:

__________________________________________________________________________
                     (Please print name and address)

__________________________________________________________________________

__________________________________________________________________________

Dated:  ____________________  Signature: __________________________

NOTICE:   The above signature must correspond with the name as written upon
          the face of the within Warrant Certificate in every particular,
          without alteration or enlargement or any change whatsoever, or if
          signed by any other person the Form of Assignment hereon must be
          duly executed and if the certificate representing the shares or
          any Warrant Certificate representing Warrants not exercised is to
          be registered in a name other than that in which the within
          Warrant Certificate is registered, the signature of the holder
          hereof must be guaranteed.

Signature Guaranteed:  ____________________________________

THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION
(BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH
MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT
TO S.E.C. RULE 17Ad-15.

                                   -5-

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