The effects of fenfluramine (hydrochloride) on the behaviors of fifteen autistic children.

Fifteen autistic individuals were involved in an investigation using fenfluramine and placebo in a double-blind crossover design. Subjects were assessed using IQ tests, the Real Life Rating Scale (RLRS), the Adaptive Behavior Scale-School Edition (ABS-SE), and videotaped play data on 8 of 12 visits, including 2 follow-up visits. Serotonin level in platelet-poor plasma was assessed on all 12 visits. Serotonin levels decreased with the administration of fenfluramine, and increased with the reinstatement of placebo. Statistical tests revealed no significant differences on the IQ scores, the RLRS, or the ABS-SE for the drug versus the placebo conditions. Videotaped data favored the subjects while on placebo. Group and individual data were analyzed over time and indicated no significant improvements due to the drug. The implications of this research make it difficult to recommend fenfluramine as a treatment for autism.