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                                                                   Exhibit 10.90


                                 BIOSHIELD (TM)

                          BIOSHIELD TECHNOLOGIES, INC.

                                  June 27, 2000



Jackson, LLC
Wilson, LLC
c/o Citco Trustees (Cayman) Ltd.
Attn: David Sims
Corporate Center, Windwood One
West Bay Road
P.O. Box 31106 SMB
Grand Cayman, Cayman Islands

         RE: BIOSHIELD TECHNOLOGIES, INC. (THE "COMPANY")

Dear Mr. Sims:

         In consideration of and as a condition to the closing of the private
placement by the parties of the Company's $10,000,000 Series B Convertible
Preferred Stock and $50,000,000 Private Equity Credit Agreement (the "2000
Equity Line") of even date herewith, the parties hereto as holders of (i) Series
A Convertible Preferred Stock; (ii) Series B Convertible Preferred Stock; (iii)
common stock, no par value, of the Company ("Common Stock") issuable pursuant to
that certain Private Equity Credit Agreement, dated as of June 1999 and the 2000
Equity Line; (iv) Electronic Medical Distribution, Inc. common stock, par value
$0.0001 per share, which is exchangeable into Common Stock; and (v) Common Stock
issued as a result of (i)-(iv) above ((i)-(v) shall be collectively referred to
as Common Stock Holders") hereby agree as follows:

         1.       Limitation on Sales of Common Stock. The Common Stock Holders
                  and their affiliates agree not to directly or indirectly at
                  any time sell more than 20,000 shares of Common Stock on any
                  Trading Day; provided, however, (i) that if the daily volume
                  of the Common Stock, as reported by Bloomberg on any Trading
                  Day is greater than 100,000 per day and less than 250,000
                  (excluding any Common Stock sold by the Common Stock Holders),
                  then the Common Stock Holders may be permitted to sell a total
                  of 40,000 shares of Common Stock on any such Trading Day; (ii)
                  that if the daily volume of the Common Stock, as reported by
                  Bloomberg on any Trading Day is greater than 250,000 and less
                  than 500,000 shares of Common Stock (excluding any Common
                  Stock sold by the

                5655 Peachtree Parkway, Norcross, Georgia 30092;
                    Tel: (770) 246-2000; Fax: (770) 368-0784
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                  Common Stock Holders) then the Common Stock Holders may be
                  permitted to sell a total of 70,000 shares of Common Stock on
                  any such Trading Day; (iii) no sales may be made within the
                  last hour of each Trading Day. Notwithstanding the foregoing
                  limitation on such sales, the holder shall be permitted to
                  sell on any Trading Day without any limitation on such sales
                  in the event that the daily trading volume (excluding any
                  Common Stock sold by the Common Stock Holders) is in excess of
                  500,000 shares on any Trading Day (preceding any Common Stock
                  held by the Common Stock Holder).

         2.       Binding Nature of Agreement. The terms of this letter are
                  intended to be binding on any transferee or assignee of the
                  Common Stock Holders and no such transfer or assignment shall
                  be effective until such transferee or assignee agrees in
                  writing to be bond by the terms of this letter.

         3.       Definitions. Terms not otherwise defined herein shall have the
                  meaning set forth in the Articles of Amendment of the Company
                  dated as of June 14, 2000.

         4.       Counterparts. This agreement may be executed in counterparts,
                  which together shall constitute a single instrument.

                                      BIOSHIELD TECHNOLOGIES, INC.

                                      By: _____________________________
                                      Name:
                                      Title:




Accepted and agreed to this 15 day of June, 2000.

JACKSON, LLC

HOLDER OF ELECTRONIC MEDICAL DISTRIBUTION, INC. COMMON STOCK

By: _______________________________________
Name:
Title:

                5655 Peachtree Parkway, Norcross, Georgia 30092;
                    Tel: (770) 246-2000; Fax: (770) 368-0784
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JACKSON LLC

BUYER OF COMMON STOCK OF BIOSHIELD TECHNOLOGIES, INC. JUNE 1999 PRIVATE EQUITY
LINE AND HOLDER OF COMMON STOCK


By: _______________________________________
Name:
Title:

WILSON LLC

HOLDER OF BIOSHIELD TECHNOLOGIES, INC. SERIES A PREFERRED STOCK

By: _______________________________________
Name:
Title:




                5655 PEACHTREE PARKWAY, NORCROSS, GEORGIA 30092;
                    TEL: (770) 246-2000; Fax: (770) 368-0784