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Polydex Pharmaceuticals Limited announces BV Trial results

Final Report of Ushercell as Treatment for Bacterial Vaginosis Released

Additional trials reinforce safety and acceptability

TORONTO, Ontario, September 17, 2007 -- Polydex Pharmaceuticals Limited (NASDAQ:POLXF) announces that a final report has been received from Dr. Jose Simoes, the Principal Investigator in a Phase II human clinical trial of Ushercell to study the potential treatment and possible prevention of bacterial vaginosis (BV). Bacterial Vaginosis is the most common vaginal disorder among reproductive-age women, commonly associated with several gynecologic and obstetric complications.

The report concludes that this study has reinforced the acceptability and safety of Ushercell, a high molecular weight cellulose sulphate gel (CS), for intravaginal use for five consecutive days. In addition, although this trial showed that CS gel is significantly less effective than metronidazole gel for the treatment of BV, its in vitro properties may still make this product useful as a preventative agent against BV recurrence following antibiotic treatment, and suggests that future studies on this possibility might be worthwhile.

George Usher, President and CEO of Polydex commented that “Although results from this trial indicate that Ushercell may not be a considerable candidate for treatment of BV, it underlines the possibility that it may be a practical excipient, or carrier of other drugs, in a variety of potential uses as it remains well tolerated and acceptable to women engaged in these important clinical trials.”

“Furthermore, Ushercell has demonstrated a pregnancy probability of only 3.9% when used as directed and our strategy is to continue development of Ushercell as a contraceptive alternative, and to seek additional uses for this unique compound, which has repeatedly established that it is as safe and acceptable as marketed spermicides, sexual lubricants and the universal placebo compound.”

As part of a long-established research and development program for Ushercell, the BV studies were undertaken as a result of earlier studies that had demonstrated a dose-dependent growth-inhibition effect of BV-associated bacteria in vitro, inhibiting the growth of many bacteria commonly associated with BV.

With positive findings in these early preclinical trials, it was theorized that Ushercell’s non-cytotoxic, broad-spectrum antimicrobial activity might inhibit an overgrowth of Gardnerella vaginalis and anaerobic microorganisms, as well as or better than currently marketed products, such as metronidazole. Ushercell was compared with metronidazole in this double-blinded study, to determine comparable effectiveness.

A particularly strict criteria defining the cure of BV was used in this trial, resulting in significantly lower cure rates in women using Ushercell than those on the same regimen using metronidazole (5% vs. 27%, respectively). In total, only eight women of the clinically evaluable participants (out of the sixty enrolled women) were really cured per the protocol of this trial, but most women reported symptomatic improvement either during the phone contact or at the test of cure visits, in both the Ushercell and the metronidazole groups.

It is important to highlight that the diagnosis of BV is not standardized and variations in diagnostic criteria employed in clinical trials or treatments for BV are widespread. In this trial, the rigorous criteria for diagnosis and cure followed precisely those recommended in the 1998 U.S. Food and Drug Administration (FDA) Guidance Document entitled “Bacterial Vaginosis – Developing Antimicrobial Drugs for Treatment”. This document calls for investigators to define BV cure as the absence of all four Amsel criteria and a Gram stain score (Nugent) of less than four (<4).

Dr. Simoes, of the University of Campinas, Sao Paulo, Brazil, explains that “Using this strict criteria, even the metronidazole users in our study were cured at a rate less than expected, only 27% at 30 days. Therefore, the low cure rates found in the present trial could partially be explained by the strict criteria for the determination of the cure of BV. If, for instance, a Nugent score of less than seven (<7) were used, it would change the Nugent score results and there would be no statistically significant difference between the two groups of treatment.”

Dr. Simoes’ report goes on to say that the general acceptability was very good (almost 90%) and even those women who reported moderate adverse effects while using the product did not stop using it throughout the course of the trial. Any self-reported symptoms of discomfort during the trial were quite mild, and apparently transitory and self-resolved because findings of general irritation were not noted at the follow-up visits. Furthermore, yeast vaginal infection occurred in only one woman of the CS group (5%) and two women of the metronidazole group (8%) at the test-of-cure visit.

Another recent study that was designed to assess the safety and acceptability of Ushercell among HIV-positive men was published in the July 2007 issue of Sexually Transmitted Diseases, and concluded that Ushercell was well tolerated with only mild irritation, likely caused by the benzyl alcohol component in the cellulose sulphate gel. This was the second study to assess the acceptability of Ushercell applied directly to men, and the first involving HIV-positive men.

Another safety and acceptability study was recently completed assessing the result of Ushercell being administered four times per day for fourteen consecutive days. The original research article from this trial will be published in the September 2007 issue of Contraception, and concludes that Ushercell is a safe and acceptable product to women participants in the trial even when used four times a day for two weeks. All women in the Ushercell group but one said she would buy the product for contraceptive use, and all of the women said they would purchase it for prevention of sexually transmitted infections.

Polydex Pharmaceuticals Limited, based in Toronto, Ontario, Canada, is engaged in the research, development, manufacture and marketing of biotechnology-based products for the human pharmaceutical market, and also manufactures bulk pharmaceutical intermediates for the worldwide veterinary pharmaceutical industry.

Note: This press release may contain forward-looking statements, within the meaning of the United States Securities Act of 1933, as amended, and the United States Securities Exchange Act of 1934, as amended, regarding Polydex Pharmaceuticals Limited, including, without limitation, statements regarding expectations about future revenues or business opportunities and developments relating to Ushercell or other potential research projects. These statements are typically identified by use of words like “may”, “could”, “might”, “expect”, “anticipate” or similar words. Actual events or results may differ materially from the Company's expectations, which are subject to a number of known and unknown risks and uncertainties including but not limited to changing market conditions, future actions by the United States Food and Drug Administration or equivalent foreign regulatory authorities as well as results of pending or future clinical trials. Other risk factors discussed in the Company's filings with the United States Securities and Exchange Commission may also affect the actual results achieved by the Company.

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Contact for Polydex Pharmaceuticals Limited: Linda Hughes, 1-877-945-1621,>

Posted: September 2007