The FDA granted approval to Eli Lilly and Company last month to market its drug olanzapine (Zyprexa) for the short-term management of acute manic episodes in bipolar disorder.

The new indication includes patients with manic or mixed episodes, with or without psychotic features, and with or without rapid cycling. Olanzapine becomes the first drug in its class to be approved for this indication. The medication originally received FDA approval in 1996 for use in the management of manifestations of psychotic disorders, such as schizophrenia.

Although its exact mechanism of action is unknown, researchers suspect that olanzapine blocks both dopamine and serotonin in the brain. In patients with schizophrenia, it controls positive, negative, and affective symptoms. In clinical trials involving bipolar patients, olanzapine appears to stabilize mood, reducing mania with little precipitation of depression.

The recommended starting dose is 10 mg to 15 mg once a day. The drug can be taken at any time, without regard to meals. It appears to be generally well tolerated; during clinical trials, however, drowsiness, dry mouth, dizziness, and loss of strength were reported significantly more in patients receiving olanzapine than in placebo groups. Unlike other medications used with bipolar disorder, olanzapine does not require blood monitoring.

The FDA’s approval of olanzapine for the new indication adds a significant option in the often difficult treatment of bipolar patients. According to Mauricio Tohen, M.D., Dr.P.H., associate clinical professor of psychiatry at Harvard Medical School, olanzapine appears to be safe, effective, and easy to administer, and has the potential to reduce the often complex combination of medications required to gain adequate control of bipolar disorder.