Background: Sexual side effects are commonly associated with serotonin reuptake inhibitor (SRI) therapy. The mechanism underlying SRI-induced sexual dysfunction has been hypothesized to be mediated by direct serotonergic effects. Evidence from open-label reports suggests that cyproheptadine, nefazodone, mirtazapine, and mianserin, which block one or more serotonin receptors, may reverse sexual side effects. The current study was a prospective, randomized, crossover trial comparing granisetron, a serotonin-3 antagonist, with placebo in outpatients who developed sexual dysfunction during SRI treatment.
Method: Thirty-one outpatients who were currently experiencing sexual dysfunction associated with SRIs were randomly assigned to double-blind treatment with granisetron (1-1.5 mg) or placebo for use 1 to 2 hours prior to sexual activity. Patients rated sexual symptoms after each trial using the Sexual Side Effect Scale (SSES). After 4 trials of the medication, patients crossed over to the other treatment for 4 more trials.
Results: Twenty patients received at least 1 dose of placebo and granisetron. Analysis by repeated-measures analysis of variance showed no significant effects of granisetron relative to placebo. Significant improvement between baseline and treatment-phase SSES scores was observed for both granisetron (p = .0004) and placebo (p = .0081). The study medication was generally well tolerated.
Conclusion: The results of this study do not support the efficacy of granisetron (1-2 mg) in the treatment of SRI-associated sexual side effects. A significant placebo response may be associated with the treatment of SRI-induced sexual dysfunction.