Fen-phen
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| Combination of | |
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| Fenfluramine | Serotoninergic |
| Phentermine | Adrenergic, dopaminergic, serotoninergic |
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| Routes of administration |
Oral |
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| Legal status | |
| Legal status |
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The drug combination fenfluramine/phentermine, usually called fen-phen, was an anti-obesity treatment that utilized two anorectics. Fenfluramine was marketed by American Home Products (later known as Wyeth) as Pondimin, but was shown to cause potentially fatal pulmonary hypertension and heart valve problems, which eventually led to its withdrawal and legal damages of over $13 billion.Phentermine was not shown to have harmful effects.
Fenfluramine acts as a serotonin releasing agent, phentermine as a norepinephrine, dopamine and serotonin releasing agent.
Fenfluramine as a single drug was first introduced in the 1970s, but was not popular because it only temporarily reduced weight. A 1984 study found a weight loss of 7.5 kg on average in 24 weeks, as compared to 4.4 kg under placebo. It sold modestly until the 1990s, when it was combined with phentermine and heavily marketed. A similar drug, aminorex, had caused severe lung damage and "provided reason to worry that similar drugs ... could increase the risk of a rare but often fatal lung disease, pulmonary hypertension." In 1994, Wyeth official Fred Wilson expressed concerns about fenfluramine's labeling containing only four cases of pulmonary hypertension when a total of 41 had been observed, but no action was taken until 1996. In 1995, Wyeth introduced dexfenfluramine (the dextro isomer, marketed as Redux), which it hoped would cause fewer adverse effects. However, the medical officer of the Food and Drug Administration (FDA), Leo Lutwak, insisted upon a black box warning of pulmonary hypertension risks. After Lutwak refused to approve the drug, the FDA management had someone else sign it and approved the drug with no black box warning for marketing in 1996. European regulators required a major warning of pulmonary hypertension risks.
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Wikipedia