CollaGenex Pharmaceuticals Files Patent Infringement Claim against IVAX Pharmaceuticals Inc. and CorePharma LLC.

NEWTOWN, Pa. -- CollaGenex Pharmaceuticals, Inc. (Nasdaq:CGPI) today announced that it has filed a complaint for patent infringement against IVAX Pharmaceuticals Inc. and CorePharma LLC ("Defendants") in the United States District Court for the Eastern District of New York. CollaGenex alleges that the Defendants' submissions of Abbreviated New Drug Applications ("ANDA's") covering their 20mg tablets of doxycycline hyclate infringe United States Patent RE 34,656, of which CollaGenex is the exclusive licensee. CollaGenex is seeking an injunction preventing the Defendants from introducing 20mg tablets of doxycycline hyclate into the market in the United States.

CollaGenex markets its proprietary 20mg tablets of doxycycline hyclate under the registered trademark Periostat(R) for the treatment of adult periodontitis. CollaGenex enforced its patents covering Periostat(R) in similar legal actions initiated in 2002 and 2003, respectively, against other ANDA applicants, West-ward Pharmaceutical Corporation and Mutual Pharmaceutical Company.

CollaGenex also continues to challenge in the United States District Court for the District of Columbia the decision of the Food and Drug Administration ("FDA") to classify Periostat(R) as an antibiotic, and has sought to compel the FDA to accord CollaGenex patent and exclusivity protection under the Hatch Waxman amendments to the Food, Drug and Cosmetic Act. The D.C. court has granted a preliminary injunction which prevents the FDA from approving any ANDA covering generic versions of Periostat(R) pending final resolution of the CollaGenex challenge.

"The use of Periostat(R) for the treatment of adult periodontitis by reducing pocket depth and increasing attachment level gain is covered by a valid patent of long standing," said Colin Stewart, president and chief executive officer of CollaGenex. "Pursuing these actions in parallel is consistent with the Company's commitment to pursue all legal avenues to defend its intellectual property rights."

CollaGenex is the exclusive licensee of patents, assigned to the Research Foundation of the State University of New York, that cover, among other things, the use of doxycycline to treat adult periodontitis. CollaGenex is undertaking further development of the drug and related compounds for other medical conditions, including rosacea, which are the subject of separate patent filings.

CollaGenex Pharmaceuticals, Inc. is a specialty pharmaceutical company focused on providing innovative medical therapies to the dental and dermatology markets. Currently, the Company's professional dental pharmaceutical sales force markets Periostat, which is indicated as an adjunct to scaling and root planing for the treatment of adult periodontitis. Periostat is the first and only pharmaceutical to treat periodontal disease by inhibiting the enzymes that destroy periodontal support tissues and by enhancing bone protein synthesis. The dental sales force also promotes Atridox(R), Atrisorb FreeFlow(R) and Atrisorb-D FreeFlow(R), Atrix Laboratories, Inc.'s products for the treatment of adult periodontitis, to the dental market. The Company's professional dermatology sales force markets Pandel(R), a prescription topical corticosteriod licensed from Altana, Inc.

Research has shown that certain unique properties of the tetracyclines discovered during the development of Periostat(R) may be applicable to other diseases involving inflammation and/or destruction of the body's connective tissues. CollaGenex is further evaluating Periostat(R), as well as the new IMPACS(R) compounds, to assess whether they are safe and effective in these other applications. In addition, CollaGenex has licensed the Restoraderm(TM) technology, a unique, proprietary dermal drug delivery system, in order to develop a range of topical dermatological products with enhanced pharmacologic and cosmetic properties.

To receive additional information on the Company, please visit our Web site at www.collagenex.com, which does not form part of this press release.

Statements in this press release, including statements relating to the litigation with IVAX and CorePharma, may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. CollaGenex' actual results could differ materially from those stated or implied in forward-looking statements due to a number of factors, including those factors contained in CollaGenex' most recent Annual Report on Form 10-K for the year ended December 31, 2003 and the most recent Form 10-Q for the Quarter ended June 30, 2004 under the sections "Additional Factors That May Affect Future Results" and "Additional Risks That May Affect Results" as well as other documents that may be filed by CollaGenex from time to time with the Securities and Exchange Commission. Forward-looking statements include statements regarding CollaGenex' expectations, beliefs, intentions or strategies regarding the future and can be identified by forward-looking words such as "anticipate", "believe", "could", "estimate", "expect", "intend", "may", "should", "will", and "would" or similar words. CollaGenex assumes no obligations to update the information included in this press release.

Periostat, IMPACS and Restoraderm are registered trademarks of CollaGenex Pharmaceuticals, Inc.

All other trade names, trademarks or service marks are the property of their respective owners and are not the property of CollaGenex Pharmaceuticals, Inc. or any of our subsidiaries.

Pandel is a trademark of Taisho Pharmaceuticals.

Atridox, Atrisorb and Atrisorb-D are registered trademarks of Atrix Laboratories, Inc.