July 24, 1997

Dear Health Care Provider:

We are writing to advise you of labeling changes being developed with the U.S. Food and Drug Administration (FDA) for two Wyeth-Ayerst products, PONDIMIN (fenfluramine hydrochloride) tablets C-IV and REDUX (dexfenfluramine hydrochloride capsules) C-IV. The revised labeling is the result of heightened concern regarding potential side effects which have been reported with concomitant use of fenfluramine and phentermine ("fen/phen").

A boxed warning will be added to the physician and patient labeling discussing a potentially serious and unusual form of valvular heart disease which has been reported in patients taking fenfluramine and phentermine. The symptoms of this disease may include dyspnea, reduced exercise tolerance and/or lower extremity edema. If patients develop these symptoms during therapy or develop a new heart murmur, physicians are advised to perform a complete cardiovascular evaluation.

The labeling for dexfenfluramine (Redux) will also include new warning language because it is a related chemical compound to fenfluramine.

Evidence of a causal relationship between the treatment of obesity with fenfluramine and phentermine combination therapy and valvular heart disease is inconclusive. Wyeth-Ayerst is initiating scientific studies to supplement currently available data.

The warning will also contain information from the current labeling on the small risk of developing primary pulmonary hypertension (PPH), an often-fatal disorder which has been associated with the use of prescription weight loss medications. PPH has symptoms which are similar to those of cardiac valvular disease.

Wyeth-Ayerst will send you the revised labeling with the boxed warning when the wording is finalized with the FDA.

Concomitant use of Pondimin tablets with other weight-loss agents is not recommended. The addition of phentermine to Pondimin ("fen/phen") is not an approved use of Pondimin.

Obesity is a serious medical condition, which now afflicts one in three adult Americans and has grown at alarming rates in recent years. Antiobesity drugs can play an important role in treating clinically obese patients when properly prescribed as part of a program that also includes a regulated diet and increased physical exercise. We are committed to ensuring that physicians and patients have as much information as possible to make an individualized benefit/risk decision.

Please contact Wyeth Ayerst Medical Affairs Department at 1-800-934-5556 if you have any questions or concerns about this information.

Sincerely,

Marc W. Deitch, M.D.
Senior Vice President
Medical Affairs and Medical Director

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