A preliminary study of the effect of norfenfluramine on lipogenesis by human adipose tissue in vitro.

1 Norfenfluramine is thought to be the major active metabolite of fenfluramine in man. Therefore its in vitro effect on lipogenesis in human adipose tissue from twelve patients was investigated. 2 Although inhibition of lipogenesis was demonstrated, the concentrations of norfenfluramine necessary (>1 mM) were much higher than normal blood levels of the drug. 3 There was no correlation between the degree of inhibition by norfenfluramine in vitro and fat cell size, age or relative weight of the subject. Greater degrees of inhibition were however associated with samples of tissue from patients with higher blood glycerol concentrations and lower blood triglyceride concentrations.