A Review of the Efficacy of Selective Serotonin Reuptake Inhibitors in Obsessive-Compulsive Disorder

Background: Obsessive-compulsive disorder (OCD) is a chronic illness associated with substantial morbidity; it often requires long-term medication. The best-studied therapeutic agent in the treatment of this disorder is the tricyclic antidepressant clomipramine. Since other tricyclic antidepressants appear to lack efficacy in OCD, that of clomipramine has been linked to its potent effects on serotonin. Consequently, agents that selectively inhibit serotonin reuptake have been the focus of several large-scale, placebo-controlled studies of OCD. Their efficacy in OCD is the focus of our review.

Data sources: MEDLINE search (1966 to present) of OCD treatment with clomipramine or SSRI antidepressant medication using the key words obsessive-compulsive disorder, serotonin reuptake inhibitors, clomipramine, and pharmacology.

Study findings: The selective serotonin reuptake inhibitors fluoxetine, sertraline, fluvoxamine, and paroxetine have, in separate multicenter trials, demonstrated efficacy and tolerability in the treatment of OCD. In contrast, clomipramine, though efficacious, is often associated with substantial adverse events, particularly anticholinergic side effects. While 2 recent meta-analyses support the superior efficacy of clomipramine over selective serotonin reuptake inhibitors in the treatment of OCD, 5 of 6 head-to-head comparisons of either fluoxetine or fluvoxamine versus clomipramine have found similar efficacy but a lower incidence of side effects with the selective serotonin reuptake inhibitor. A recently completed multicenter, 12-week, double-blind trial of paroxetine versus clomipramine versus placebo showed paroxetine to be as effective as clomipramine. With significantly fewer dropouts due to adverse effects than clomipramine, paroxetine was also associated with superior tolerability.

Conclusion: The suggestion that selective serotonin reuptake inhibitors possess efficacy similar to that of clomipramine, but have a superior side effect profile, may have important implications for patients with OCD who require long-term treatment.