A comparison of the effects of d- and l-fenfluramine and d-amphetamine on energy and macronutrient intake in human subjects.
The anorectic activity of the d and l isomers of d-fenfluramine (d-FF) (l-FF) were compared with d-amphetamine (d-amp) when given separately and together in 12 healthy male volunteers. The study was double blind and placebo controlled. Food intake was measured using an automated food dispenser. Anorectic activity was examined using a) total energy intake b) nutrient selection c) selection of foods categorised by nonsweet/sweet taste. Total energy intake was significantly reduced by d-FF (17%) d-amp (26%) d-FF + d-amp (36%) and l-FF + d-amp (31%). d-Amp and both combinations significantly reduced energy intake from all macronutrients in the total food. d-FF reduced carbohydrate but not fat or protein intake derived from all foods. When nonsweet and sweet tasting foods were examined separately, l-FF also significantly reduced energy (by 19%), fat and carbohydrate intake from nonsweet food. Neither d-FF nor l-FF reduced protein from nonsweet food. No anorectic drug given alone reduced sweet food intake, only d-amp given with d-FF had this effect. In contrast to nonsweet food, d-FF did not reduce carbohydrate from sweet foods. The results are in agreement with previous work that d-FF spares protein consumption but suggest that d-FF does not selectively reduce carbohydrate intake per se.