Topiramate augmentation in refractory obsessivecompulsive disorder: A randomized, double-blind, placebo-controlled trial

Background: This study aimed to assess the efficacy of topiramate, a glutamate-modulating agent, in patients with treatment-resistant obsessive-compulsive disorder (OCD) as an adjunct to serotonin reuptake inhibitors (SRIs). Materials and Methods: Thirty-eight patients with refractory OCD, were randomly assigned to receive topiramate or placebo. This study was designed as a 12 weeks, double-blind, placebo-controlled trial. Primary outcome measures were the change in Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) score and the rate of treatment response in each group at the study end point. Treatment response was considered as 25% or more reduction in Y-BOCS score. Results: A total of 13 patients in the topiramate group and 14 ones in the placebo group completed the trial. Topiramate-assigned patients showed significantly improved mean Y-BOCS score over time (P < 0.001). Although differences between two groups were significant in the Y-BOCS score at the first 2 months (P = 0.01), this was not significant at the end of the study (P = 0.10). Changes of Clinical Global Impression (CGI)-Severity of Illness Scale score and CGI-Improvement Scale score were not significantly different between two groups (P > 0.05). Treatment response was almost significantly different in the topiramate group comparing placebo group (P = 0.054). Mean topiramate dosage was 137.5 mg/day (range, 100-200). Conclusion: This study didn’t show efficacy of topiramate as an agent to augment SRIs in treatment-resistant OCD patients.