Olanzapine, a thienobenzodiazepine derivative, is a psychotropic agent that has shown efficacy in the treatment of patients with bipolar I disorder. Olanzapine has a multireceptorial binding profile including a greater affinity for serotonin 5-HT(2A) than for dopamine D(2) receptors. Olanzapine 5 to 20 mg/day demonstrated significantly greater antimanic efficacy than placebo in two double-blind, randomised 3- or 4-week trials of patients with bipolar I disorder of either manic or mixed episodes, with or without psychotic features. Additionally, in one of these trials, improvements in cognitive function and hostility were superior with olanzapine. In cohorts of severely depressed and rapid cycling patients, improvements in manic and depressive symptoms and in manic symptoms only, were superior with olanzapine compared with placebo. Significant improvements from baseline in symptoms of mania, depression, cognitive functioning and hostility were seen with olanzapine in a 49-week extension phase study. In double-blind trials, olanzapine 10 mg/day appeared to have similar antimanic efficacy to oral lithium 400mg twice daily in the treatment of patients with pure mania (4-week small study). In patients with acute manic or mixed episodes olanzapine 5 to 20 mg/day appeared to be more effective than oral valproate semisodium (divalproex sodium) 500 to 2500 mg/day (3-week study) and at least as effective as oral haloperidol 3 to 15 mg/day (12-week study). Preliminary results from a large 6-week placebo-controlled study suggest that olanzapine 5 to 20 mg/day in combination with mood stabilisers (lithium or valproate semisodium) provides effective augmentation of antimanic treatment of patients with bipolar I disorder, with benefits seen in the first week. Adverse events reported significantly more often with olanzapine than with placebo were somnolence, dry mouth, dizziness and bodyweight gain, and in comparison with valproate semisodium were somnolence, dry mouth, increased appetite and bodyweight gain. Olanzapine was generally well tolerated with no clinically relevant abnormalities in laboratory tests, vital signs or electrocardiogram results.
Conclusion: Olanzapine demonstrated superior efficacy compared with placebo in the short-term treatment of patients with bipolar I disorder with manic or mixed episodes, with or without psychotic features, and was generally well tolerated. According to preliminary data the antimanic efficacy of olanzapine appears similar to that of haloperidol and better than that of valproate semisodium in patients with bipolar I disorder experiencing a manic or mixed episode; among nonpsychotic patients with manic or mixed episodes olanzapine appears to be superior to haloperidol. Available data support the choice of olanzapine as an option in the short-term management of mania in patients with bipolar I disorder with manic or mixed episodes, with or without psychotic features.