Olanzapine: a review of its use in the management of bipolar I disorder.

Olanzapine is an atypical antipsychotic that is approved in the US and Europe for the oral treatment of acute manic episodes in patients with bipolar I disorder, and for maintenance therapy to prevent recurrence in responders. Oral olanzapine is effective in the treatment of bipolar mania, both as single agent therapy and as adjunctive therapy in combination with lithium or valproate semisodium. In the treatment of acute episodes, olanzapine is superior to placebo and at least as effective as lithium, valproate semisodium, haloperidol and risperidone in reducing the symptoms of mania and inducing remission. Additional comparative studies are required to determine the efficacy of olanzapine relative to newer atypical antipsychotics, such as quetiapine, ziprasidone and aripiprazole. Olanzapine is also effective at delaying or preventing relapse during long-term maintenance therapy in treatment responders, and is currently the only atypical antipsychotic approved for this indication. Current evidence suggests that olanzapine may be more effective than lithium in preventing relapse into mania, but not relapse into depression or relapse overall. Olanzapine is generally well tolerated, and although it is associated with a higher incidence of weight gain than most atypical agents, it has a low incidence of extrapyramidal symptoms (EPS). Therefore, oral olanzapine is a useful first-line or adjunctive agent for both the acute treatment of manic episodes and the long-term prevention of relapse into manic, depressive or mixed episodes associated with bipolar I disorder.