Central nervous system effects of fenfluramine hydrochloride.

Fenfluramine is a phenethylamine compound with a structure similar to that of amphetamine. These two structurally similar compounds possess several major differences in pharmacologic properties, especially with regard to their effects on the central nervous system. d -Amphetamine produced a dose-related increase of spontaneous motor activity (SMA) in mice; however, dl -fenfluramine decreased the SMA in a dose-related manner. Biocimemical studies revealed that dl -fenfluramine decreased the content of norepinephrine and dopamine in mouse and rat brain. Pretreatment of mice with a monoamine oxidase inhibitor reversed the effect of dl -fenfluramine from one of significant decrease of SMA to one of a marked increase of SMA; however, the ability of d -amphetamine to increase SMA of mice was enhanced by prior monoamine oxidase inhibition. These data suggest that d -amphetamine and dl -fenfluramine differ in their interaction with central adrenergic neurons to produce their respective SMA effects in mice.