Figure 3. Forest plot showing the frequency

of weight loss (>7%) at 12 weeks in randomized controlled trials comparing amantadine and placebo for olanzapine-induced weight gain (N = 144). For, frequency of body weight loss >7% (N = 144), the test for heterogeneity was not significant (p = 0.45, I 2 = 0%) and the fixed-effects model was used. The Mantel–Haenszel odds ratio for weight loss was 3.72 (95% CI 1.19–11.62), favoring amantadine as Inhibitors,research,lifescience,medical compared with placebo, and the overall effect was significant (p = 0.02). Discussion Existing data shows that the weight mitigating effect of amantadine at doses of 100–300 mg per day was statistically significant as compared with placebo in patients with olanzapine-induced weight gain, although the results are based on a small sample (N = 144). In these studies, amantadine was well tolerated with some adverse effects, such as insomnia and upper abdominal discomfort were significantly higher than placebo. There is no evidence of worsening of symptoms Inhibitors,research,lifescience,medical after the addition of amantadine. Nevertheless, these data may not be sufficient to recommend routine use of amantadine for the treatment

of olanzapine-induced weight gain. Inhibitors,research,lifescience,medical It is interesting to note that odds of significant weight loss (>7% initial body weight) was higher in those receiving amantadine (odds ratio [OR] 3.72, 95% CI 1.19–11.62) as compared with the placebo group. It appears that a subset of patients might have benefited from treatment with amantadine. In a recent post hoc analysis of studies evaluating weight-reducing agents (nizatidine, amantadine Inhibitors,research,lifescience,medical and sibutramine) as adjunctive treatment to olanzapine therapy, it was observed that these medications do not benefit all patients, but might have therapeutic potential for

some patients [Stauffer et al. 2009]. In future, prospective studies Inhibitors,research,lifescience,medical are required for identification of these subsets of patients who will benefit from such treatments. Furthermore, the search for genetic mechanisms underlying the drug response in antipsychotic-induced metabolic dysfunction is important. Terminal deoxynucleotidyl transferase Selleckchem Imatinib Preliminary results have shown that leptin tended to increase after placebo whereas there was a small nonsignificant reduction after metformin, in spite of similar weight gain suggests a beneficial effect of this antidiabetic agent in olanzapine-induced weight gain [Baptista et al. 2007]. In another study by Fernandez and colleagues, specific genetic polymorphism of leptin gene showed a blunted response to metformin in clozapine-treated patients [Fernández et al. 2010]. Such pharmacogenetic studies will identify specific subsets of patients who will benefit from treatment with anti-obesity medications during antipsychotic treatment. Our review is limited by the number of studies included for meta-analysis. Fewer studies did not allow us to conduct tests for publication bias.