A systematic review of metformin to limit weight-gain with atypical antipsychotics

WHAT IS KNOWN AND OBJECTIVE: Weight-gain is commonly reported in patients taking atypical antipsychotic agents. A systematic review was performed to evaluate the effectiveness of metformin for attenuation of weight-gain induced by atypical antipsychotic agents. METHODS: A PubMed database (1966-May 2010) search was conducted, using metformin, atypical antipsychotic and weight-gain as search terms. Review articles, letters and commentaries were excluded. RESULTS AND DISCUSSION: Thirteen trials were identified (eight randomized, double-blind, placebo-controlled trials, one crossover adult trial, one open-label uncontrolled adult trial, two open-label uncontrolled paediatric trials and one case report). Of the eight randomized, double-blind, placebo-controlled trials, three studied adult subjects and one studied children. Metformin was well tolerated. The heterogeneity of the trials did not justify meta-analytic pooling of outcomes, and we provide a best evidence synthesis. WHAT IS NEW AND CONCLUSION: There is limited evidence for the efficacy of metformin in limiting weight-gain induced by atypical antipsychotic agents. However, the evidence is weak and further well-powered randomized, double-blind, placebo-controlled studies of longer duration should be conducted to confirm the preliminary evidence and provide better estimates of effect.