Distribution of fenfluramine in normal and obese mice.

Concentrations of fenfluramine and its metabolite, norfenfluramine, were measured in blood, brain and parametrial adipose tissues 15, 30, 60 and 120 min after intraperitoneal (i.p.) administration of fenfluramine hydrochloride (10 mg/kg) to normal and gold-thioglucose obese mice. Concentrations of fenfluramine were higher in the brain of obese mice than in normal mice, while there was no difference in norfenfluramine levels in the two groups. This difference may be related to higher blood levels of fenfluramine but not of norfenfluramine in obese animals. The drug was presented in about the same concentrations in the adipose tissue of the two groups. These results may explain previous findings that fenfluramine was more effective as an anorectic agent in obese than in lean mice.