D-, L- and DL-fenfluramine cause long-lasting depletions of serotonin in rat brain.

D-Fenfluramine (1.6-12.5 mg/kg), L-fenfluramine (1.6-25 mg/kg), and DL-fenfluramine (1.6-25 mg/kg) injected s.c. twice daily for 4 consecutive days produced dose-related depletions of serotonin (5-HT) levels in somatosensory cortex, striatum, hypothalamus, and hippocampus of rats (n = 5-8/group) sacrificed two weeks after the last injection. While the results indicate that long-lasting effects of racemic fenfluramine are due to both stereoisomers, the magnitude of depletions caused by the isomers varied with dose, suggesting that they have different neurochemical effects.