High levels of dopamine D2 receptor occupancy with low-dose haloperidol treatment: a PET study.
OBJECTIVE
The purpose of this study was to determine the dopamine D2 receptor occupancy induced by low-dose haloperidol treatment in a prospective trial.


METHODS
Seven patients with schizophrenia were treated with 2 mg/day of haloperidol for 2 weeks, and D2 receptor occupancy was measured by [11C]raclopride and positron emission tomography.


RESULTS
The patients showed high levels of D2 occupancy (53%-74%); five of them showed substantial clinical improvement, and none showed important side effects.


CONCLUSIONS
The findings demonstrate that low doses of haloperidol induce D2 receptor occupancies that are in the putative therapeutic range. In combination with recent empirical trials, these findings should encourage clinicians to initiate treatment of psychotic episodes with low (2-4 mg haloperidol equivalent) doses of typical neuroleptics, particularly for first-episode patients.
Kapur
S
S
PET Centre, Clarke Institute of Psychiatry, Toronto, Ont., Canada. kapur@clarke-inst.on.ca
Remington
G
G
Jones
C
C
Wilson
A
A
DaSilva
J
J
Houle
S
S
Zipursky
R
R
D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000378:metabolism; D002250:Carbon Radioisotopes; D004305:Dose-Response Relationship, Drug; D005260:Female; D006220:Haloperidol / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000494:pharmacology; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D020891:Raclopride; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000378:metabolism*; D012457:Salicylamides; D012559:Schizophrenia / Q000188:drug therapy* / Q000378:metabolism; D012565:Schizophrenic Psychology; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D017448:Receptors, Dopamine D2; D012457:Salicylamides; D020891:Raclopride; D006220:Haloperidol