CollaGenex Pharmaceuticals Announces that Court Maintains Preliminary Injunction Preventing the FDA from Approving any Generic Versions of Periostat.

NEWTOWN, Pa. -- CollaGenex Pharmaceuticals, Inc. (Nasdaq:CGPI) today announced that the U.S. District Court for the District of Columbia has maintained the preliminary injunction preventing the U.S. Food and Drug Administration from approving any generic versions of Periostat(R). In maintaining the preliminary injunction, Honorable Judge Collyer ordered expedited briefing of the issue of whether or not Periostat was correctly classified as an antibiotic.

A motion by IVAX Pharmaceuticals Inc. and CorePharma LLC to dissolve the preliminary injunction was heard by Honorable Judge Collyer on November 18, 2004. The injunction had originally been ordered pending final resolution of CollaGenex's challenge to the FDA's decision to classify Periostat(R) as an antibiotic, thereby denying CollaGenex the patent and exclusivity protection otherwise available under the Hatch Waxman amendments to the Food, Drug and Cosmetic Act. CollaGenex continues to challenge the FDA's decision.

Separately, CollaGenex recently filed a complaint for patent infringement against both IVAX Pharmaceuticals Inc. and CorePharma LLC ("Defendants") in the United States District Court for the Eastern District of New York. In that case, CollaGenex alleges that the Defendants' submissions of 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 is the exclusive licensee of valid patents that cover, among other things, the use of Periostat to treat adult periodontitis. We will vigorously pursue all legal avenues to defend our patent rights," said Colin Stewart, president and chief executive officer of CollaGenex.

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 may be applicable to other diseases involving inflammation and/or destruction of the body's connective tissues. CollaGenex is further evaluating Periostat and other IMPACS(TM) compounds, including Oracea(TM), to assess whether they are safe and effective in these other applications. Oracea is currently in Phase III clinical trials to evaluate its effectiveness in treating rosacea, a dermatological condition, and Col-3 is in clinical trials to evaluate its potential effectiveness in treating acne and Kaposi's sarcoma, an HIV-related skin condition. In addition, CollaGenex has acquired 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.

Forward-Looking Statements

Statements in this press release, including statements relating to the litigation with the FDA and 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 September 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 U.S. 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.