Fluvoxamine combination therapy with tropisetron for obsessive-compulsive disorder patients: A placebo-controlled, randomized clinical trial.

Background: About 50% of obsessive-compulsive disorder patients still suffer significant symptoms even after the recommended first-line therapy. This demonstrates the necessity to investigate strategies to improve alleviation of symptoms.
Objective: The main objective of this study was to investigate the efficacy of a 5-hydroxytryptophan 3 receptor antagonist, tropisetron, as an adjuvant therapy to selective serotonin reuptake inhibitors, in ameliorating obsessive-compulsive disorder symptoms.
Methods: Men and women between the ages of 18-60 years diagnosed with obsessive-compulsive disorder, based on DSM5, who had a Yale-Brown obsessive compulsive scale score of more than 21 were recruited in a double-blinded, parallel-group, placebo-controlled, clinical trial of 10 weeks to receive either tropisetron (5 mg twice daily) and fluvoxamine (100 mg daily initially followed by 200 mg daily after week 4) or placebo and fluvoxamine. The primary outcome of interest in this study was the Yale-Brown obsessive compulsive scale total score decrease from baseline.
Results: One hundred and eight participants were equally randomized into two groups; 48 participants in each group finished the trial. The Yale-Brown obsessive compulsive total score significantly dropped in both groups while the tropisetron group participants experienced a significantly higher decrease in their scores (Greenhouse-Geisser F (1.53-65.87)=3.516, p -value=0.04). No major adverse effect was observed in any of the groups.
Conclusion: This trial showed a significant efficacy for tropisetron over placebo in treatment of obsessive-compulsive disorder symptoms when added to fluvoxamine.