Issues in the monopharmacotherapy and polypharmacotherapy of obsessive-compulsive disorder.

Polypharmacotherapy is again becoming common place in clinical practice. Obsessive-compulsive disorder (OCD) as a single primary diagnosis is responsive exclusively to the serotonin reuptake inhibitors (SRIs) and this fact forms the major evidence supporting a central role for 5-HT (serotonin) in the pathogenesis of the disorder. Presently, the highly potent serotonin reuptake inhibitors clomipramine, fluoxetine, fluvoxamine, and paroxetine are the only agents approved by the Food and Drug Administration (FDA) for OCD, but there is evidence that other SRIs, such as sertraline, are also effective. Because OCD is often treatment refractory and highly comorbid with other psychiatric disorders, the use of polypharmacotherapy can be justified. Other serotonergic medications such as lithium, buspirone, trazodone, or fenfluramine may be useful as adjuvant treatments in treatment-refractory OCD and adjuvant antipsychotics are useful in tic disorders, personality disorders, and psychotic disorders. The usefulness of polypharmacotherapy should be tempered by adverse effects including the serotonin syndrome, withdrawal phenomena, extrapyramidal side effects, and drug-drug interactions.