In vivo assay for neuroleptic receptor binding in the striatum. Positron tomography in humans.

Using PET, we investigated the potency in six patients of therapeutic doses of neuroleptic drugs for preventing specific binding of trace doses of intravenously administered 76Br-labelled bromospiperone to corpus striatum in vivo. Measured receptor occupancy showed a clear-cut dose-dependent saturation curve with increasing daily oral dose of neuroleptics, indicating the validity and reliability of the method when used as an in vivo radioreceptor assay. Following drug withdrawal in eight patients, recovery to normal or supranormal receptor availability occurred in a matter of days. The results demonstrate an approach that may help resolve controversies about, and design better strategies for, neuroleptic treatment schedules.