Fenfluramine received FDA approval in 1973 for the short-term treatment of obesity. Fen-Phen® refers to the combination, or cocktail, of fenfluramine or Pondimin® (the "Fen") and phentermine (the "Phen"). Together, phentermine and fenfluramine produced a powerful diet drug cocktail.

The FDA never approved the Fen-Phen® combination, but once the agency has approved a drug, doctors may prescribe it at will. Their use, together, was considered "off-label".

In 1992, Dr. Michael Weintraub of the University of Rochester and several colleagues published a study citing Fen-Phen® as a more effective method than dieting or exercise in reducing the weight of the chronically obese. Even better - Fen-Phen®, unlike an earlier generation of speed-laden diet drugs, seemed to be without immediate side effects.

The Fen-Phen® cocktail became an overnight sensation. 1996 saw 6.6 million prescriptions of Fen-Phen® in the U.S.

However, this combination was never effectively tested for safety. The result was that by the summer of 1997, the Mayo Clinic reported 24 cases of heart valve disease. All 24 people had taken the Fen-Phen® cocktail. The cluster of unusual cases of heart valve disease in Fen-Phen® users suggested a co-relation between Fen-Phen® use and heart valve disease.

On July 8, 1997 the FDA issued a Public Health Advisory to report the Mayo findings (which were later published in the August 28 issue of the New England Journal of Medicine). Please click here to read the FDA Health Advisory.

The FDA continued to received additional reports of heart disease, including reports from patients who had taken only fenfluramine.

Further evaluations of patients taking fenfluramine, showed that approximately 30% had abnormal valve findings. This figure is much higher than expected for abnormal test results and suggest fenfluramine as the likely cause of Primary Pulmonary Hypertension (PPH) and valvular heart disease.

The FDA responded promptly to the alarming findings, and in September 1997, requested drug manufacturers to voluntarily withdraw fenfluramine. At the same time, the FDA recommended that patients using fenfluramine stop taking it. To view the FDA September 1997 statement regarding the withdrawal, please click here.

The FDA did not, however, request the withdrawal of the second drug involved in the cocktail, phentermine.

Please visit the official site of the FDA for further information.

 

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