topiramate augmentation in refractory obsessive- compulsive disorder: a randomized, double-blind, placebo-controlled trial

background: this study aimed to assess the effectiveness 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-week, 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: 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 was significant in the y-bocs score at the first two months (p=0.01), this was not significant at the end of 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 effectiveness of topiramate as an agent to augment sris in treatment-resistant ocd patients.