Extrastriatal dopamine D2 receptor occupancy in olanzapine-treated patients with schizophrenia

Olanzapine is described as a multi-actingreceptor-targeted antipsychotic agent. Although regionaldifferences of dopamine D2 receptor occupancy, i.e., limbicselectivity, were reported for olanzapine, contradictoryresults were also reported. We measured dopamine D2receptor occupancy of olanzapine in extrastriatal regionsin patients with schizophrenia using positron-emissiontomography with [11C]FLB457 and the plasma concentrationsof olanzapine. Ten patients with schizophrenia taking5–20 mg/day of olanzapine participated. Dopamine D2receptor occupancy in the temporal cortex ranged from61.1 to 85.8%, and plasma concentration was from 12.7 to115.4 ng/ml. The ED50 value was 3.4 mg/day for dose and10.5 ng/ml for plasma concentration. The ED50 valuesobtained in this study were quite similar to those previouslyreported in the striatum. In conclusion, although the subjectsand methods were different from previous striataloccupancy studies, these results suggest that limbic occupancyby olanzapine may not be so different from that inthe striatum