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EXHIBIT 4.12

                         ADDENDUM TO FIRST AMENDMENT TO
             8% SECURED CONVERTIBLE DEBENTURE DUE FEBRUARY 28, 2002

         THIS ADDENDUM TO FIRST AMENDMENT TO 8% SECURED CONVERTIBLE DEBENTURE
DUE FEBRUARY 28, 2002 (this "Addendum") is made and effective as of September
24, 2001, by and between BIOGAN INTERNATIONAL, INC., a Delaware corporation (the
"Company"), and THOMSON KERNAGHAN & CO., LIMITED, a Canadian limited liability
company (the "Holder").

                                 R E C I T A L S

         A. Effective as of September 24, 2001, the Company and the Holder
entered into the First Amendment to 8% Secured Convertible Debenture due
February 28, 2002 ("First Amendment").

         B. The Company and the Holder desire to add an additional term to the
First Amendment on the terms and conditions set forth herein.

                                A G R E E M E N T

         NOW, THEREFORE, for and in consideration of the premises and the mutual
covenants set forth herein and in the First Amendment, the parties hereto do
hereby agree as follows:

         1.       Amendment to Section 4E of the Debenture.
                  ----------------------------------------

                  The first sentence of Section 4E of the Debenture is hereby
         amended and restated to read in its entirety as follows:

                  "E. Notwithstanding any other provision hereof, of the
         Warrants, of any of the other Transaction Agreements (as those terms
         are defined in the Securities Purchase Agreement) or of the Company's
         Amended Certificate of Designations of Series A Convertible Preferred
         Stock, in no event (except (i) with respect to an automatic conversion,
         if any, of a Debenture as provided in the Debentures, (ii) as
         specifically provided in this Debenture as an exception to this
         provision, or (iii) while there is outstanding a tender offer for any
         or all of the shares of the Company's Common Stock) shall the Holder be
         entitled to convert all or any portion of this Debenture or to convert
         all or any shares of Series A Convertible Preferred Stock (and the
         Company shall not have the right to pay interest on this Debenture in
         shares of Common Stock) to the extent that, after such conversion, the
         sum of (1) the number of shares of Common Stock beneficially owned by
         the Holder and its affiliates (other than shares of Common Stock that
         may be deemed beneficially owned through the ownership of the
         unconverted portion of the Debentures or unconverted shares of Series A
         Convertible Preferred Stock), and (2) the number of shares of Common
         Stock issuable upon conversion of the Debentures or Series A
         Convertible Preferred Stock or upon exercise of the Warrants with
         respect to which the determination of this proviso is being made, would
         result in beneficial ownership by the Holder and its affiliates of more
         than 9.99% of the outstanding shares of Common Stock (after taking into
         account the shares to be issued to the Holder upon such conversion or
         exercise).


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         2.       Miscellaneous.
                  -------------

                  (a) All other terms and provisions of the Debenture and the
         First Amendment not expressly modified by this Addendum shall remain in
         full force and effect; provided, however, that to the extent any
         provisions of the Debenture, the First Amendment or any of the other
         Transaction Agreements (as defined in the Securities Purchase
         Agreement) are in conflict with the provisions of this Addendum, the
         provisions of this Addendum shall control.

                  (b) This Addendum, along with the Debenture, the other
         Transaction Agreements and the First Amendment to Registration Rights
         Agreement, shall constitute and contain the complete understanding and
         agreement of the parties hereto, and cancel and supersede any and all
         prior negotiations, correspondence, understandings and agreements,
         whether written or oral, between the parties with respect to the
         subject matter hereof.

         IN WITNESS WHEREOF, the parties have executed this Addendum to be
effective as of September 24, 2001.

Dated: October 3, 2001                          BIOGAN INTERNATIONAL, INC.


                                                By: /S/ G. Laverdiere
                                                    ----------------------------
                                                    Its: President
                                                         -----------------------



Dated: October 3, 2001                          THOMSON KERNAGHAN & CO., LIMITED


                                                By: /S/ Gregg Badger
                                                    ----------------------------
                                                    Its: Sr. VP & Director
                                                         -----------------------