[Effect of Topiramate on Drug Associated Weight Gain of Patients with Schizophrenia and Bipolar I Disorders: A Dose Ranging Randomized Trial]

Abstract

Introduction: The aim of this study was to explore the probable prophylactic effects and evaluate different doses of topiramate on body weight in patients treated with olanzapine.

Materials and methods: This was a 12 week, double-blind, placebo-controlled clinical trial (Iranian Clinical Trial Registration Code: 201402085280N15) to assess the preventative effects and estimate the optimal dosage of topiramate in drug-induced weight gain. Sixty eight patients aged 18 to 60 that were hospitalized and treated with olanzapine between 2009-2011due to the onset of an acute episode of schizophrenia or a manic episode of bipolar I disorder were selected in Mashhad, the second largest city in the northeast of Iran. Patients were randomly assigned to 4 groups, including 1- placebo; 2- 50 mg/day; 3- 100 mg/day; and 4- 200 mg/day topiramate. Two psychiatrists assigned participants to an intervention group and followed up the treatment process. Raters weighed patients at baseline and also at weeks 1, 2, 4, 6, 8, and 12, respectively. Waist and wrist circumferences were measured at baseline and weeks 4, 8, and 12. Body weight, BMI, wrist, and waist circumference changes were outcome measures of the study. Collected data were analyzed by ANOVA, post hoc Tukey test, Kruskal-Wallis, Mann-Whitney U, and Cohen's d with SPSS version 14. A p-value of less than 0.05 was considered significant.

Results: All outcome measures were significantly less than the placebo group compared to the topiramate groups at the end of the fourth week and continued to twelfth week. Nevertheless, there was no statistically significant difference in the measures of any of the topiramate groups with each other at any interval.

Conclusion: All doses of 50, 100, and 200mg were shown effective in preventing olanzapine-related obesity in schizophrenic and/or bipolar patients.