Metformin may help offset weight gain in pediatric patients taking psychotropic medications, according to an open label study reported in the April issue of the American Journal of Psychiatry. "In this preliminary evaluation of metformin as a treatment for weight gain associated with psychotropic drugs, the steep increase in weight experienced from these drugs was arrested in all patients," write John A. Morrison, PhD, from the Children’s Hospital Medical Center in Cincinnati, Ohio, and colleagues.
Of 19 children, aged 10 to 18 years, receiving olanzapine, risperidone, quetiapine, or valproate, 15 were white and 4 were black, and there were 12 boys and 7 girls. Each patient received metformin, 500 mg three times daily, in a 12-week open-label study.
Of the 19 patients, 15 lost weight, 3 gained up to 1.6 kg, and 1 patient had no change. The mean changes in weight and body mass index at 12 weeks were highly significant. One patient who gained 1.6 kg was also receiving intramuscular medroxyprogesterone acetate, which can also cause weight gain.
Despite several limitations of this preliminary study and the need for randomized controlled trials, the authors conclude that "the pattern of sustained, continued weight loss suggests that the weight loss was not due to the placebo effect. Metformin holds promise as a treatment for weight gain in pediatric patients taking psychotropic medications." Am J Psychiatry. 2002;159(4):655-657