In 1997 the FDA asked American Home Products (AHP), the makers of Pondimin (Fenfluramine) and Redux (Dexfenfluramine), to withdraw it's popular anti-obesity combination Fen-Phen drug from the market. AHP manufactured fenfluramine under the brand name Pondimin and AHP's subsidiary, Wyeth-Ayerst Laboratories, manufactured dexfenfluramine under the name Redux. Medical studies have linked Pondimin and Redux to heart valve disease.
In a report by the FDA, the agency cited a Mayo Clinic study that found 30 percent of patients taking fenfluramine and dexfenfluramine had abnormal echocardiograms, even though they had no symptoms. This is a higher than expected percentage of abnormal test results.
The Mayo Clinic study, published in the New England Journal of Medicine on August 28, 1997, also suggested that as high as one-third of patients sampling Fen-Phen had evidence of heart valve disease.
In addition to heart valve disease, the use of fenfluramine and dexfenfluramine has been found to increase the risk of developing Primary Pulmonary Hypertension or (PPH). PPH is a rare disease of that causes the progressive narrowing of the blood vessels of the lungs. Studies estimate that treatment with certain appetite suppressant drugs tends to increase the chances of developing PPH by approximately 25 to 30 percent.
In 2000, American Home Products agreed to pay as much as $3.75 billion to settle lawsuits over its Redux and Pondimin diet drugs, in what would be a record injury settlement involving a pharmaceuticals company. The agreement would provide benefits, ranging from drug refunds to injury payments of as much as $1.4 million a person, for the six million or so people who took the drugs. The amounts individuals are entitled to recover under this Settlement depend on the person's age at diagnosis of valvular heart disease, the person's "Level of Severity."
As of March 2001, 45,000 former users have refused the settlement and retained the right to sue for punitive damages. Some 266,000 others have registered to join the class and may still reject the settlement and sue for compensatory damages but not punitive damages.