Olanzapine (Zyprexa): Characteristics of a new antipsychotic

Olanzapine is a thienobenzodiazepine antipsychotic, which exerts broad-spectrum receptor antagonism in the central nervous system. It demonstrates regionally selective dopamine antagonist activity as measured with the depolarisation block model and the fos activation paradigm. Early in vivo imaging studies suggest a relatively low D₂ occupancy in the striatum (69%) with a higher 5-HT₂ occupancy in the cortex (84%) of 10 mg. Its pharmaco-kinetics are dose-proportional; T(max) is 5 h and the elimination half-life is 31 h (range: 21 - 54 h). Efficacy studies show equivalent antipsychotic efficacy to haloperidol with the possibility of superior efficacy on negative symptoms and depression. Motor side-effects are minimal with mild akathisia emerging at the highest doses; non-motor side-effects are also minimal. Olanzapine is a highly effective antipsychotic drug with minimal side-effects. It will be an important new drug for treating schizophrenia.