October 29, 2003

News Release: Procyon Reports Issuance of U.S. Patent for its Novel HIV Anti-Integrase Family of Compounds

Procyon Biopharma Inc. (TSX: PBP) announced today that it has been granted U.S. patent no. 6,638,921 relating to its antiretroviral program. The small molecule compounds described in the patent entitled 'Pyridoxal-5-phosphate derivatives as HIV integrase inhibitors' constitute a novel family of compounds that demonstrate dual inhibitory activity against both the purified enzyme and HIV in infected cell cultures. 'The integrase enzyme represents a novel and challenging HIV-native enzyme encoded in the HIV genome that constitutes a promising and exciting new therapeutic target,'said Hans J. Mader, President and CEO of Procyon Biopharma Inc. 'We believe that this patent reiterates the R&D capability of Procyon in the domain of HIV enzyme inhibition while providing increased protection for our anti-integrase program,'he added.

Upon infection, the HIV reverse transcriptase enzyme converts the viral RNA into DNA which then moves from the cytoplasm into the host cell nucleus where it is spliced into the host genome with the help of the HIV integrase enzyme. This 'provirus'DNA is then involved in the production of RNA for viral progeny. Integration thus is key to viral propagation and represents an important target for therapeutic intervention, for HIV and potentially for other retroviruses as well.

To date, there are no anti-integrase drugs available on the market and Procyon's novel family of anti-integrase compounds is one of very few known anti-integrase programs currently under exploration. The Company's anti- integrase molecules are undergoing lead compound optimization and differ from the other known compounds in their unique chemical structure.

Procyon's virology division has spent over four years developing its proprietary compound library of small molecules targeting the HIV viral integrase. With this third patent relating to the anti-integrase program, Procyon now has US patent protection over three families of compounds, namely the hydroxyphenyl, aromatic and pyridoxal derivatives. Patents are pending in other jurisdictions.

About Procyon Biopharma

Procyon Biopharma Inc. is a publicly traded, Montreal-based, Canadian biotechnology company actively engaged in the discovery and development of innovative therapeutics and diagnostics in the fields of oncology and infectious diseases. Procyon brings its products and technologies from the laboratory to phase II human clinical trials and licenses them to larger pharmaceutical partners for further development and commercialization. Procyon's pipeline comprises a healthy combination of early-stage anti-cancer platforms, PSP94 and ANsA, as well as anti-HIV/AIDS compounds, PL-100, a protease inhibitor, and PL-2500, a lead candidate integrase inhibitor. The Company also has two late-stage products: Fibrostat(R), licensed to Biovail Corporation, and Colopath(R)/ColorectAlert(TM), licensed to IMI International Medical Innovations Inc. Procyon shares are listed on the Toronto Stock Exchange (TSX) under the ticker symbol PBP. (www.procyonbiopharma.com)

This release contains forward-looking statements that reflect the company's current expectation regarding future events. The forward-looking statements involve risks and uncertainties. Actual events could differ materially from those projected herein and depend on a number of factors including, but not limited to, changing market conditions, successful and timely completion of clinical studies, uncertainties related to the regulatory approval process, establishment of corporate alliances and other risks detailed from time to time in the company's filings.

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For further information: Christian Marcoux, Manager, Investor &Public Relations, Procyon Biopharma Inc., (514) 685-2000 ext. 118, C. (514) 602-5628, cmarcoux(at)procyonbiopharma.com

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