Comparing the efficacy of ondansetron and granisetron augmentation in treatment-resistant obsessive-compulsive disorder: a randomized double-blind placebo-controlled study.

This study aimed to assess the efficacy and tolerability of ondansetron vs. granisetron in patients with treatment-resistant obsessive-compulsive disorder. A randomized clinical trial conducted on 135 patients with a Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) diagnosis of obsessive-compulsive disorder, who were treatment-resistant and receiving stable treatment with selective serotonin reuptake inhibitors and antipsychotic, received 14 weeks (phase I, intervention period) of placebo (n = 45), ondansetron (n = 45, 4 mg), and granisetron (n = 45, 2 mg) daily augmentations.