[Olanzapine: a second generation antipsychotic drug and an "atypical" mood stabilizer?].

The term "mood stabilizer" has been widely used since the early 1990's but it still does not have a uniform and generally accepted definition. Usually, agents that are effective in ameliorating acute manic or depressive episodes and have some prophylactic efficacy against the recurrence of new phases are considered as mood stabilizers. Lithium is unquestionably the prototype drug of this class; others, like some anticonvulsants, have been subsequently added to the list. Recent clinical research indicates that some of the newer second-generation antipsychotics may have very similar properties. In controlled clinical studies of acute manic and mixed episodes, olanzapine has proved to be at least as effective as lithium, divalproex, or haloperidol - often with additional benefits, such as faster onset of action, or wider spectrum of target symptoms. Added to mood stabilizers, olanzapine significantly enhances their antimanic efficacy. It also has intrinsic antidepressant properties; and in combination with fluoxetine, this has resulted in convincing efficacy in bipolar depressive episodes. Long-term maintenance treatment with olanzapine has extended the periods of remission and shown prophylactic efficacy against the recurrence of both manic and depressive episodes that is comparable or, in the case of preventing manic relapses, even superior to lithium. While none of the current agents meet the most stringent criteria for an "ideal" mood stabilizer, there is strong evidence that olanzapine, just like lithium, is effective across all phases of bipolar disorder without provoking either manic or depressive symptomatology. Regardless of formal definition criteria, this is exactly what clinicians expect of a dependable mood stabilizer.