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                                                                     EXHIBIT 3.1

                          SECOND ARTICLES OF AMENDMENT
                                     TO THE
                            ARTICLES OF INCORPORATION
                                       OF
                                 ENTROPIN, INC.

     Pursuant to Section 7-106-102 of the Colorado Business Corporation Act,
Entropin, Inc. (the "Corporation") adopts the following Second Articles of
Amendment to its Articles of Incorporation, as amended and restated:

     1.   The Articles of Incorporation, as amended and restated, hereby are
amended to add the following paragraph to Article VII of the Articles of
Incorporation, as amended and restated:

               CLASSIFICATION OF DIRECTORS. The directors shall be divided into
          three classes, designated Class I, Class II and Class III. Each class
          shall consist, as nearly as possible, of one-third of the total number
          of directors constituting the entire Board of Directors. The term of
          the initial Class I directors shall terminate on the date of the 2001
          annual meeting of Shareholders; the term of the initial Class II
          directors shall terminate on the date of the 2002 annual meeting of
          Shareholders; and the term of the initial Class III directors shall
          terminate on the date of the 2003 annual meeting of Shareholders. At
          each meeting of Shareholders beginning in 2001, successors to the
          class of directors whose term expires at that annual meeting shall be
          elected for a three-year term. If the number of directors is changed,
          any increase or decrease in directorships shall be apportioned among
          the classes so as to maintain the number of directors in each class as
          nearly equal as possible, and any additional directors of any class
          elected to fill a vacancy resulting from an increase in such class
          shall hold office until the next election of directors of such class
          by the Shareholders, but in no case will a decrease in the number of
          directors shorten the term of any incumbent director. Directors shall
          hold office until the annual meeting for the year in which their terms
          expire and until their successors shall be elected and shall qualify,
          subject, however, to prior death, resignation, retirement,
          disqualification or removal from office. Any vacancy on the Board of
          Directors, howsoever resulting, may be filled by the affirmative vote
          of a majority of the remaining directors then in office, even if less
          than a quorum. Any director elected to fill a vacancy shall hold
          office until the next election of directors of such class by the
          Shareholders.

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     3.   This Amendment was duly adopted by the Shareholders of the Corporation
on June 14, 2000.

     On behalf of Entropin, Inc., Higgins D. Bailey, Chairman of the Board of
Directors, by his signature below, does hereby confirm, under the penalties of
perjury, that the foregoing Second Articles of Amendment to the Articles of
Incorporation, as amended and restated, of Entropin, Inc. are a true and correct
copy of said document.

                                           ENTROPIN, INC.

                                           By /s/ Higgins D. Bailey
                                              ------------------------
                                              Higgins D. Bailey
                                              Chairman of the Board