AGREEMENT AMONG SHAREHOLDERS
                                       OF
                                 ENTROPIN, INC.

Board of Directors
Entropin, Inc.
45926 Oasis Street
Indio, California 92201

Dear Sirs:

This  letter  is  being  delivered  to you in  connection  with  the  Form  SB-2
Registration Statement (the "Registration  Statement") filed by Entropin,  Inc.,
(the "Company") with the United States  Securities and Exchange  Commission (the
"SEC").  In  accordance  with the  Registration  Statement,  the  holders of the
Company's  Common Stock whose  shares are being  registered  thereby  (including
those of the undersigned) will be free-trading without restriction or limitation
at the time of the  Registration  Statement being declared  effective by the SEC
(the "Effective Date").

The Company has advised the undersigned  that securities  underwriters and other
sources  of  potential  future  funding  of the  Company  may  require  that the
undersigned  and other  shareholders  set forth below agree to not offer or sell
all or a portion of their shares of the Company's  Common Stock. The Company has
requested the undersigned to agree thereto.

Therefore, in consideration of each of the shareholders set forth below entering
into this Agreement,  the undersigned  agrees not to offer,  sell or contract to
sell or otherwise  dispose of,  directly or indirectly,  or announce an offering
of, any shares of the Company's  Common Stock owned by the  undersigned  (or any
securities convertible into, or exchangeable for, shares of the Company's Common
Stock) for a period of 365 days following the Effective Date.

In the event that,  during the term of this  Agreement,  the Company permits the
sale or other disposition of a portion of shares (a "Permitted  Disposition") by
the  undersigned  shareholders,  it shall do so on a pro rata  basis.  Since the
shares are being  registered in the Registration  Statement,  the shares will be
free-trading upon a Permitted Disposition during the term of this Agreement,  or
a  disposition  after  the  expiration  of this  Agreement,  provided  that  the
Registration  Statement  is current at the time of a  disposition.  The  Company
hereby  undertakes  to use its best efforts to keep the  Registration  Statement
current.

Yours very truly,
                                        /s/ Higgins D. Bailey and Shirley A.
                                            Bailey
Date:  June 29, 1998                    ------------------------------------
                                        Higgins D. Bailey and Shirley A.
                                        Bailey




                                        /s/ Higgins D. Bailey
Date:  June 29, 1998                    ------------------------------------
                                        Higgins D. Bailey, Pledgee


                                        /s/ James E. Wynn
Date:  June 29, 1998                    ------------------------------------
                                        James E. Wynn


                                        /s/ Donald Hunter
Date:  June 29, 1998                    ------------------------------------
                                        Donald Hunter,
                                        Trustee for the Donald Hunter
                                        Residuary Marital Trust


                                        /s/ Deloras Decker Hunter
Date:  June 29, 1998                    ------------------------------------
                                        Deloras Decker Hunter,
                                        Trustee of the Deloras Decker Hunter
                                        Generation Skipping Trust


                                        /s/ Dewey H. Crim/Virginia Crim
Date:  June 29, 1998                    ------------------------------------
                                        Dewey H. and Virginia Crim


                                        /s/ Caroline T. Somers
Date:  June 29, 1998                    ------------------------------------
                                        Caroline T. Somers


                                        /s/ Milton D. McKenzie
Date:  June 29, 1998                    ------------------------------------
                                        Milton D. McKenzie


                                        CapMac Eighty-Two Limited Partnership,


Date:  June 29, 1998                    By:/s/ Milton D. McKenzie
                                           ---------------------------------
                                           Milton D. McKenzie, General Partner





                                        2



                                            /s/ Milton D. McKenzie
Date:  June 29, 1998                        -----------------------------------
                                            Milton D. McKenzie, Pledgee


                                            /s/ Chandler G. Brown
Date:  June 29, 1998                        -----------------------------------
                                            Chandler G. Brown


                                            Thomas T. Anderson Trust,


Date:  June 29, 1998                        By: /s/ Thomas T. Anderson
                                               --------------------------------
                                               Thomas T. Anderson, Trustee


                    AGREED TO AND ACCEPTED BY ENTROPIN, INC.




Date:  June 29, 1998                        By: /s/ Higgins D. Bailey
                                                -------------------------------
                                                 Higgins D. Bailey,
                                                 Chairman of the Board


                                        3