Dexfenfluramine neurotoxicity in brains of non-human primates.

Dexfenfluramine, a drug prescribed for appetite suppression, was evaluated in non-human primates for its potential to produce toxic effects on brain serotonin (5-HT) neurons. Squirrel monkeys received dexfenfluramine subcutaneously twice daily for four days at doses of 1.25 or 5.00 mg/kg. Two weeks later, a dose-related depletion of 5-HT and 5-hydroxyindoleacetic acid was found, together with a reduced number of 5-HT uptake sites. Morphological studies showed acute pathological changes in 5-HT axons, followed by a persistent decrease in 5-HT axon density. Our findings indicate that dexfenfluramine damages central 5-HT neurons in monkeys and raise concern about the potential neurotoxicity of this drug in man.