Fenfluramine in Prader-Willi syndrome: a double blind, placebo controlled trial

A double blind trial was conducted to determine the effect of fenfluramine on the weight and behaviour of patients with the Prader-Willi syndrome. Fifteen subjects, aged 5.5 to 27 years, received the placebo and the active drug, each for a period of six weeks. The dose of fenfluramine varied according to the age of the patient. Treatment with fenfluramine was associated with significant weight loss, improvement in food related behaviour, and a decrease in aggressive behaviour directed towards others. Skin picking and other self mutilation were unaffected by the drug. None of the subjects suffered from any side effects while taking the drug. These findings suggest that short term treatment with fenfluramine may have a role in the management of some patients with Prader-Willi syndrome. It could be used during periods when exposure to large amounts of food cannot be avoided and aggressive behaviour is particularly difficult to contain. It may also be useful in those whose lives are threatened by the complications of obesity.