U.S. Department of Health and Human Services
P97-32 FOOD AND DRUG ADMINISTRATION
FOR IMMEDIATE RELEASE Lawrence Bachorik: (301) 827-6250
September 15, 1997 Broadcast Media: (301) 827-3434
Consumer Hotline: (800) 532-4440

FDA ANNOUNCES WITHDRAWAL OF FENFLURAMINE AND DEXFENFLURAMINE

The action is based on new findings from doctors who have evaluated patients taking these two drugs with echocardiograms, a special procedure that can test the functioning of heart valves. These findings indicate that approximately 30 percent of patients who were evaluated had abnormal echocardiograms, even though they had no symptoms. This is a much higher than expected percentage of abnormal test results.

"These findings call for prompt action," said Michael A. Friedman, M.D., the Lead Deputy Commissioner of the FDA. "The data we have obtained indicate that fenfluramine, and the chemically closely related dexfenfluramine, present an unacceptable risk at this time to patients who take them."

FDA recommends that patients using either of these products stop taking them. Users of these two products should contact their doctors to discuss their treatment.

These new findings suggest fenfluramine and dexfenfluramine are the likely cause of heart valve problems of the type that prompted FDA's two earlier warnings concerning "fen-phen," a combination of fenfluramine and phentermine. "Fen-phen" has been widely used off-label in recent years for the long-term management of obesity.

In July, researchers at the Mayo Clinic and Mayo Foundation reported 24 cases of rare valvular disease in women who took the "fen-phen" combination therapy. FDA alerted medical doctors that it had received nine additional reports of the same type, and requested all health care professionals to report any such cases to the agency's MedWatch program (1-800-FDA-1088/fax 1-800-FDA -0178) or to the respective pharmaceutical manufacturers.

Subsequently, FDA received 66 additional reports of heart valve disease associated mainly with "fen-phen." There were also reports of cases seen in patients taking only fenfluramine or dexfenfluramine. FDA requested that the manufacturers of fenfluramine and dexfenfluramine stress the potential risk to the heart in the drugs' labeling and patient package inserts. FDA continues to receive reports of cardiac valvular disease in persons who have taken these drugs.

• Brand name in US: Redux
• Class: serotonin reuptake inhibitor and releasing agent
• For: treatment of obesity
• Route of Administration: oral
• Controlled Substance Class: Schedule IV
• Information for Patients:

  Patients should be informed that false-positive urine drug tests for amphetamines have been observed for up to 24 hours following a 30-mg dose (2 capsules) of Redux.

  A warning about Primary Pulmonary Hypertension, a rare, but frequently fatal complication, should also be discussed by your doctor when considering starting this medication (1).

  There seems to be an increased risk of valvular heart disease associated with fenfluramine and phentermine ("fen-phen") (2); dexfenfluramine is a form of fenfluramine.

• Action: Stimulates the release, and blocks the inactivation, of serotonin, thereby increasing the levels of serotonin in the brain, "convincing" the brain that the body has ingested more food than it actually has (signaling satiety, in other words). Also appears to selectively suppress carbohydrate intake without affecting protein intake; improves blood glucose levels independent of its weight-loss effect.
• Manufacturer: Interneuron Pharmaceuticals (Lexington, Mass), for Wyeth Laboratories Inc
• Status: Approved April, 1996 for sale in the United States; launch date June 9, 1996; already used in many other countries
• Source of Information: Diabetes Self-Management, Jan/Feb, 1996; product insert, 4/29/96

References:

(2) Connolly HM, Crary JL, McGoon MD, et al. Valvular heart disease associated with fenfluramine-phentermine. N Engl J Med 1997; 337:581-8.