CollaGenex Pharmaceuticals Provides Update on 40 mg Cohort of Phase II Dose-Finding Study of Incyclinide for the Treatment of Acne.

NEWTOWN, Pa. -- CollaGenex Pharmaceuticals, Inc. (NASDAQ:CGPI) today announced that it has learned that one patient has experienced apparent significant photo-toxicity, a known side effect of tetracyclines, while participating in the 40 mg cohort of its Phase II dose-finding study of incyclinide for the treatment of acne. The Company is currently investigating this adverse event and has suspended enrollment of all new patients in the study. After completing its investigation, CollaGenex will meet with the FDA to discuss the ongoing development program for incyclinide.

Colin Stewart, president and chief executive officer of CollaGenex, said, "Our principal concern is the safety of our patients, and we are suspending further enrollment in the 40 mg cohort of this trial while we investigate this adverse event. Since we observed no adverse events at lower doses, we are continuing the Phase II dose-finding trial of incyclinide for the treatment of rosacea."

Conference Call

As previously announced, CollaGenex will hold a conference call on Wednesday, May 2, at 11:00 a.m. Eastern Daylight Time to discuss the Company's first quarter 2007 financial results and the contents of this press release. Investors and other interested parties may access the conference call by dialing [phone] in the U.S. or [phone] internationally, or via a live webcast on the Company's website at www.collagenex.com.

For those who cannot listen to the live webcast, a replay will be available shortly after the call at www.collagenex.com for 90 days. Additionally, a recording of the call will be available by telephone until 11:59 p.m. on May 9, 2006 by dialing [phone] in the U.S. or [phone] internationally, and entering access code 8696027.

About CollaGenex

CollaGenex Pharmaceuticals, Inc. is a specialty pharmaceutical company currently focused on developing and marketing proprietary, innovative medical therapies to the dermatology market. In July 2006, CollaGenex launched Oracea, the first FDA-approved systemic product for the treatment of rosacea. CollaGenex's professional dermatology sales force also markets Pandel, a prescription topical corticosteroid licensed from Altana, Inc., Alcortin(R) (1% iodoquinol and 2% hydrocortisone), a prescription topical antifungal steroid combination, and Novacort(R) (2% hydrocortisone acetate and 1% pramoxine HCl), a prescription topical steroid and anesthetic. Alcortin and Novacort are marketed by the Company under a Promotion and Cooperation agreement with Primus Pharmaceuticals, Inc. CollaGenex is conducting two Phase II dose-finding studies to evaluate its second dermatology candidate, incyclinide, for the treatment of acne and rosacea, respectively. CollaGenex is also conducting Phase II clinical trials to evaluate COL-118, a topical compound based on the SansRosa technology, for the treatment of redness associated with rosacea and other skin disorders.

Research has shown that compounds can be created by chemically modifying certain tetracyclines and that these new compounds have properties that may make them effective in treating diseases involving inflammation and/or destruction of the body's connective tissues. CollaGenex is evaluating various chemically modified tetracyclines (so called "IMPACS"(TM) compounds because they are Inhibitors of Multiple Proteases And CytokineS) to assess whether they are safe and effective in these applications. The Company has a pipeline of innovative product candidates with possible applications in dermatology and other disease states. In addition, CollaGenex has acquired the SansRosa(TM) technology, which consists of a class of compounds that have shown promise in reducing the redness associated with rosacea, and the Restoraderm(R) technology, a unique, proprietary dermal drug delivery system. CollaGenex plans to leverage these platforms to develop a range of topical dermatological products with enhanced pharmacologic and cosmetic properties.

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

Statements in this press release regarding management's future expectations, beliefs, intentions, goals, strategies, plans or prospects, including statements relating to the Company's revenue, net loss and expenses and future cash position, including the first quarter of 2007 and for the remainder of fiscal year 2007, and its future research and development efforts, including the Company's clinical and development programs relating to Oracea, incyclinide and COL-118 and its dermatology franchise, product pipeline and intellectual, property, may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements can be identified by terminology such as "anticipate," "believe," "could," "could increase the likelihood," "estimate," "expect," "intend," "is planned," "may," "should," "will," "will enable," "would be expected," "look forward," "may provide," "would" or similar terms, variations of such terms or the negative of those terms. Such forward-looking statements involve known and unknown risks, uncertainties and other factors including those risks, uncertainties and factors referred to in the Company's Annual Report on Form 10-K for the year ended December 31, 2006 filed with the Securities and Exchange Commission under the section "Risk Factors," as well as other documents that may be filed by CollaGenex from time to time with the Securities and Exchange Commission. As a result of such risks, uncertainties and factors, the Company's actual results may differ materially from any future results, performance or achievements discussed in or implied by the forward-looking statements contained herein. CollaGenex is providing the information in this press release as of this date and assumes no obligations to update the information included in this press release or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Periostat(R), Restoraderm(R) and Oracea(R) are registered trademarks and IMPACS(TM) and SansRosa(TM) are trademarks of CollaGenex Pharmaceuticals, Inc.

Novacort(R) and Alcortin(R) are trademarks of Primus Pharmaceuticals, Inc.

Pandel(R) is a trademark of Taisho Pharmaceuticals.

Atridox(R), Atrisorb(R) and Atrisorb-D(R) are registered trademarks of Tolmar, Inc.

MetroGel(R) is a registered trademark of Galderma S.A.

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.