Dopamine Receptor Occupancy and Plasma Haloperidol Levels

Abstract

To the Editor.— The kinetics of receptor-ligand interaction predict a curvilinear relationship between free brain ckade (inset). 6 5 4 in 3 2 e d c e a m x o p p A i 0 10 20 30 40 50 60 Plasma Haloperidol Level, ng/mL 20 40 60 80 100 Plasma Haloperidol Level, ng/mL ligand concentration or neuroleptic plasma level and dopamine receptor occupancy. Based on positron emission tomography (PET) studies using 11C-raclopride in several subjects, Farde et al1 recently presented a theoretical binding curve for this relationship. Cambon et al²derived a similar curvilinear relationship from 76Br-labeled bromospiperone PET scans of six subjects who had varying diagnoses and were receiving either haloperidol or thioproperazine. We conducted similar studies using the D2 radioligand 18F-j!V methylspiperone (NMS) to estimate dopamine receptor availability in patients with schizophrenia. Subjects included patients who were not receiving neuroleptic therapy and others who were treated