FEN-PHEN (or Phen-Fen) and Dexfen-Phen - two passing trends

Fen-Phen refers to the combination, or cocktail, of Fenfluramine or Pondimin (the “Fen”) and Phentermine (the “Phen”). Fenfluramine was approved by FDA in 1973 for the short-term management of obesity. The combination of Phentermine and Fenfluramine produced a powerful diet cocktail. It was never approved by FDA, yet once the agency has approved a drug, doctors may prescribe it if a patient wishes. Their use together , was considered “off-label”.

In 1992, Dr. Michael Weintraub of the University of Rochester and several colleagues published a study, which proved that Fen-Phen method is more effective in reducing the weight of the chronically obese than dieting and exercise.

Moreover, unlike an earlier drugs treating obesity, Fen-Phen seemed to be without immediate side effects. The Fen-Phen cocktail became an overnight sensation.

In 1996, 6.6 million prescriptions of Fen- Phen were estimated in US.

Another combination was created in order to support obesity treatment: Dexfen-Phen. It is a combination, or cocktail of Dexfenfluramine ( approved by FDA in 1996)or Rudux (the “Dexfen”) and Phentermine (the “Phen”).

The two combinations had one major disadvantage- neither was tested for safety…

It didn’t take much time to see the results of such misbehavior. 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 co- relation between Fen-Phen use and heart valve disease was obvious.

FDA reacted immediately. On July 8, 1997, it 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 receive additional reports of heart disease, including reports from patients who had taken only Fenfluramine or Dexfenfluramine.

Patients taking Fenfluramine and Dexenfluramine were further examined. The result was alarming: approximately 30% had abnormal valve findings. This meant possibility that Fenfluramine and Dexenfluramine cause Primary Pulmonary Hypertension (PPH) and valvuar heart disease.

The FDA responded without delay and in September 1997, requested drug manufacturers to voluntarily cancel Fenfluramine and Dexenfluramine. Patients were supposed to stop using them. If you are interested in FDA September 1997 statement regarding the withdrawals, please click here.

The third drug involved in cocktails, Phentermine, was not cancelled.