NEWTOWN, PA - (July 25, 2003) - CollaGenex Pharmaceuticals, Inc. (Nasdaq: CGPI) today announced that it has successfully completed initial Phase 1 clinical studies to establish the pharmacokinetics of its lead formulation of a sustained release (SR), once-daily version of its lead product, Periostat®. These single-dose pharmacokinetic studies have confirmed that the formulation falls within the company's pre-defined criteria for maximum serum concentration and total dose delivered, which will enable development to progress to the next stage.

   The development of Periostat SR was conducted in conjunction with Shire Laboratories Inc., a subsidiary of Shire Pharmaceuticals Group plc (LSE: SHP, NASDAQ: SHPGY, TSX: SHQ), and utilizes Shire's proprietary controlled release delivery technology.

   Certain novel features of the lead Periostat SR formulation have led to the filing of specific intellectual property protection for this particular formulation of the drug. Manufacturing development is currently underway and, following confirmative steady-state pharmacokinetic studies, which will be conducted in the 3rd quarter of 2003, it is anticipated that definitive clinical studies will begin before the end of 2003.

   "We are pleased to announce that Shire's proprietary technology has enabled us to overcome the substantial challenges associated with the development of a sustained-release version of Periostat," said Brian M. Gallagher, PhD, chairman, CEO and president of CollaGenex Pharmaceuticals. "We have achieved our objectives ahead of timeline and within budget, a tribute to our collaborators and the management skills of the manufacturing and development team at CollaGenex. This program is key to our future and we continue to devote a substantial portion of our R&D budget to ensuring its success."

   Shire Laboratories Inc. is the advanced drug delivery subsidiary of Shire Pharmaceuticals Group plc. Shire Laboratories markets its Predictive Lead Selection Technology (ProScreen™) and Predictive Formulation Optimization Technology (OptiScreen®) to the pharmaceutical industry along with its proven and patented oral controlled release formulation technologies, Microtrol®, Solutrol®, and EnSoTrol®.

   CollaGenex Pharmaceuticals, Inc. is a specialty pharmaceutical company currently focused on providing innovative medical therapies to the dental and dermatology markets. Currently, the Company's 115-person 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 sales force also promotes Vioxx®, a Merck & Co. drug that CollaGenex co-promotes for the treatment of acute dental pain; Denavir®, a Novartis Group prescription anti-viral medication for the treatment of cold sores; Sirius Laboratories' AVAR™ product line for the topical control of acne vulgaris, rosacea and seborrheic dermatitis; and Atridox®, Atrisorb® FreeFlow™ and Atrisorb-D® FreeFlow™, Atrix Laboratories Inc.'s products for the treatment of adult periodontitis.

   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, including acne, rosacea, meibomianitis and cancer metastasis, among others. CollaGenex is further evaluating Periostat, as well as the new IMPACS® compounds, to assess whether they are safe and effective in these applications. In addition, CollaGenex has licensed the Restoraderm™ 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.

This press release contains forward-looking statements within the meaning of Section 21E of the Securities and Exchange Act of 1934, as amended. Investors are cautioned that forward-looking statements involve risks and uncertainties, which may affect the Company's business and prospects. The Company's business of selling, marketing and developing pharmaceutical products is subject to a number of significant risks, including risks relating to the implementation of the Company's sales and marketing plans for Periostat® and other products that the Company markets, the outcome and consequences of the patent litigation against West-ward and Mutual and the outcome of litigation initiated by Mutual, risks that the FDA will approve generic products, such as West-ward's or Mutual's products, that will compete with and limit the market for Periostat, risks inherent in research and development activities, risks associated with conducting business in a highly regulated environment and uncertainty relating to clinical trails of products under development, all as discussed in the Company's periodic filings with the U.S. Securities and Exchange Commission.

Periostat®, IMPACS® and Metastat® are registered trademarks, and Restoraderm™is a trademark, 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.

VIOXX® is a trademark of Merck & Co., Inc.

Denavir® is a registered trademark of Novartis Consumer Health, Inc.

AVAR™is a trademark of Sirius Laboratories, Inc.

Atridox® and Atrisorb® are registered trademarks, and FreeFlow™ is a trademark, of Atrix Laboratories, Inc.

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