Metformin has been associated with clinically significant weight loss in people taking the anti-psychotic clozapine.
The systematic review and meta-analysis that included eight studies of people taking clozapine who did not have diabetes found that metformin was superior to placebo in terms of weight loss (-3.12kg, 95%CI -4.88kg to -1.37kg) and BMI (-1.18kg/m2, 95%CI -1.76kg/m2 to -0.61kg/m2).
The type 2 diabetes drug also improved waist circumference, fasting glucose and triglycerides, the researchers from the University of Queensland in Brisbane reported in PLOS One.
“With appropriate training, psychiatrists should be competent to prescribe metformin for people on clozapine with metabolic syndrome but without diabetes,” they wrote.
According to the authors the clinically relevant weight loss of over 3kg associated with metformin use suggests it could be an appropriate adjuvant for people on clozapine who are overweight and obese.
“It may be worth adding metformin, as tolerated, to the treatment protocols for people with obesity on clozapine,” they added.