Haloperidol plasma levels and clinical response: a therapeutic window relationship.
OBJECTIVE
The purpose of the study was to assess the relationship between plasma haloperidol and clinical response.


METHODS
Sixty-nine newly admitted drug-free schizophrenic men were randomly assigned to receive haloperidol, 5, 10, or 20 mg daily for 4 weeks, and clinical response was measured at the end of the fixed-dose period. Haloperidol was assayed by a sensitive and specific radioimmunoassay.


RESULTS
The authors found a curvilinear relationship between clinical response and plasma haloperidol during fixed-dose treatment, with an apparent optimum between 5 and 12 ng/ml. When plasma levels above 12 ng/ml were lowered to the 5-12 ng/ml range, all patients improved to varying degrees and no patient deteriorated. When plasma levels of nonresponders within this therapeutic window were raised above 12 ng/ml (as in routine practice), they, on balance, deteriorated in that they became more dysphoric. With the 20-mg dose, half the patients had plasma levels above 12 ng/ml.


CONCLUSIONS
In this sample of newly admitted schizophrenic men, optimal clinical response occurred with a plasma haloperidol range of 5-12 ng/ml.
Van Putten
T
T
VA, Brentwood Division, Los Angeles, CA.
Marder
S R
SR
Mintz
J
J
Poland
R E
RE
D000328:Adult; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D006220:Haloperidol / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D006760:Hospitalization; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000188:drug therapy*; D012565:Schizophrenic Psychology
D006220:Haloperidol