Efficacy of olanzapine: an overview of pivotal clinical trials.

Olanzapine is a new "atypical" antipsychotic agent that belongs chemically to the thienobenzodiazepine class. Its relatively greater binding affinity for 5-HT2 compared to D2 receptors makes it similar to the atypical agent clozapine, a serotonin/dopamine antagonist. Four double-blind pivotal studies, which compare olanzapine to placebo and/or haloperidol, are presented. The results suggest that olanzapine is as effective as haloperidol for positive symptoms and more effective than haloperidol for the treatment of the negative symptoms of schizophrenia.