The researchers found that significantly more patients in the metformin group resumed menstruation, compared to patients in the placebo group (66.7% versus 4.8%, P<0.001). Metformin also assisted in reducing weight and improving insulin resistance. BMI decreased by a mean of 0.93 in the metformin group, compared to mean decrease in BMI of 0.85 in the control group. The insulin-resistance index decreased significantly in the metformin group, but there was no comparably significant change in the placebo group.

There were significant decreases in mean prolactin levels in the metformin group, but not in the placebo group. Decreases in the mean LH and testosterone levels and the LH/FSH levels in the metformin group were significantly greater than those in the placebo group. Importantly, there were no significant differences in the frequency and type of adverse events reported between the two groups.

The researchers commented, “Weight gain, metabolic abnormalities, prolactin elevation, and amenorrhea are important side effects of antipsychotics. Metformin provides a new option for managing these complications.” They noted that metformin might be particularly useful in managing these complications in patients who present with coexisting amenorrhea, weight gain, and metabolic syndrome. They concluded, “This study has shown clearly that the addition of metformin to antipsychotics is a potential treatment to restore antipsychotic-induced amenorrhea in female patients with schizophrenia.”

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