Haloperidol blocks the uptake of [¹⁸F]N‐methylspiroperidol by extrastriatal dopamine receptors in schizophrenic patients

We had previously demonstrated extrastriatal uptake of [¹⁸F]N‐methyl‐spiroperidol (¹⁸F‐NMS) in the human brain. This study evaluates the effect of haloperidol on ¹⁸F‐NMS binding in extrastriatal brain regions. Six schizophrenic patients on haloperidol underwent two PET scans with ¹⁸F‐NMS at 12 h and at 6 days after haloperidol withdrawal. There was a significant increase in ¹⁸F‐NMS uptake in striatal, thalamic, and temporal regions but not in frontal, occipital, or cerebellar regions, following drug withdrawal. Haloperidol's ability to block the uptake of ¹⁸F‐NMS is an indication of the specificity of the radioligand's binding in these regions and supports the postmortem data demonstrating the presence of dopamine D₂ receptors in the thalamus and temporal cortex of the human brain. © 1995 Wiley‐Liss, Inc.