Metformin for antipsychotic related weight gain. Amer Jl Psych.Sept.2013

16.10.2013

Metabolic syndrome is a significant contributor to diminished life expectancy among those taking antipsychotics for long years. Life style interventions, switching to lower risk medications as well as use of weight control medications have been attempted to address this huge problem. Do we have enough evidence to use metformin in routine practice to reduce weight and improve metabolic parameters?

Jarskog et al report the results of the  largest study to date of metformin in antipsychotic-treated patients.They found that 16 weeks of 1,000 mg of metformin twice daily in antipsychotic-treated adults was effective in reducing body weight compared to placebo. All participants received a standardised healthy lifestyle intervention. Metformin was associated with a 3 kg weight loss that was significantly greater than the small weight reduction of 1.0 kg in the placebo group. Weight loss is only modest ie mean percent weight loss was only 2.8% of baseline weight with metformin compared with 1.0% with placebo. Metformin was  associated with significantly lower triglyceride and hemoglobin A1C levels than placebo. Those with younger age ( less than 44 years old), lower BMI , male sex, and nonsmoking status were associated with greater weight loss with metformin.

In the accompanying editorial Correl et al provide a glimpse of summative evidence for metformin. The 11 studies so far, indicate that:  Metformin significantly reduces body weight. The loss is modest only (3 kg). Significant benefits are observed for  some lipid and glucose parameters. Metformin is well tolerated. Weight seems to be regained after stopping metformin 

Conclusions: Given the modest weight loss and regain of weight once metformin is stopped, It is essential that psychosocial interventions (Nutritional counseling, increasing caloric expenditure, portion control, motivational enhancement with goal setting, self-monitoring of daily food and activity levels, activity plans etc) are attempted first and continued through out the period the person is on antipsychotics.

Summary of the article: 

Jarskog LF, Hamer RM, Catellier DJ, Stewart DD, LaVange L, Ray N, Golden LH, Lieberman JA, Stroup TS; for the METS Investigators: Metformin for weight loss and metabolic control in overweight outpatients with schizophrenia and schizoaffective disorder. Am J Psychiatry 2013; 170:1032–1040

Metformin for antipsychotic-related weight gain and metabolic abnormalities: when, for whom, and for how long?

Correll CU, Sikich L, Reeves G, Riddle M. Am J Psychiatry. 2013 Sep 1;170(9):947-52

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