Olanzapine: Psychopharmacology, Clinical Efficacy, and Adverse Effects

Olanzapine is an atypical antipsychotic that has a pharmacological profile similar that of clozapine. It is biotransformed by hepatic enzymes and can be dosed on a once-daily basis. In large, double-blind, placebo-controlled trials, olanzapine was shown to be efficacious in the treatment of schizophrenia relative to placebo. Many trials showed superior efficacy to haloperidol, especially against negative symptoms. Olanzapine is FDA-approved for the treatment of psychotic disorders, though data suggest possible use in depression, bipolar disorder, psychogenic polydipsia, and developmental disabilities. Olanzap-ine appears to be well-tolerated. Commonly reported adverse effects include orthostatic hypotension, sedation, hepatic transaminase elevations, weight gain, headache, agitation, dizziness, and constipation. The incidence of extrapyramidal symptoms and tardive dyskinesia is low. Few drug interactions have been reported. The recommended starting dose is 10 mg once daily. One trial indicated that the higher cost of this agent might be offset by a reduction in overall hospitalization costs.