It was a sorely needed study: compare sibutramine (Meridia) with topiramate (Topamax) in patients with psychotropic- associated weight gain. Sibutramine is generally considered one of the most effective weight loss agents. However, it inhibits the reuptake of both serotonin and norepinephrine, leading to reluc- tance to use it for patients with bipolar disorder, who could theoretically experi- ence manic switches. In this study, 46 patients with bipolar disorder and obesity were randomly assigned to sibutramine (mean dose, 12 mg/day) or topiramate (mean, 209 mg/day). Weight loss was sim- ilar for both, with an average of 4% body weight loss in the sibutramine group vs. 3% in the topiramate group. Many patients dropped out before 24 weeks, but interestingly more patients dropped out due to mood worsening in the topira- mate group than the sibutramine group, implying that the fears of manic switching may be over-blown.

TCPR’s Take: Since there was no placebo control, we don't know for cer- tain that patients' weight loss was due to a specific effect of either of these meds. But the data imply that sibutramine is safe and effective for weight loss in bipo- lar disorder. (McElroy SL et al., Bipolar Disorders 2007;9:426-434).