Fenfluramine is a drug that was part of the Fen-Phen anti-obesity medication (the other drug being phentermine). Also known as Pondimin, fenfluramine was introduced on the U.S. market in 1973. It is designed to increase the level of the neurotransmitter serotonin. This depresses the central nervous system, regulating mood and appetite. The end result is a feeling of fullness and loss of appetite.
The drug was withdrawn from the U.S. market in 1997 after reports of heart valve disease and pulmonary hypertension.