Am J Psychiatry 1992; 149:500-505
Copyright © 1992 by American Psychiatric Association
Haloperidol plasma levels and clinical response: a therapeutic window relationship
T Van Putten, SR Marder, J Mintz and RE Poland
VA, Brentwood Division, Los Angeles, CA.
OBJECTIVE: The purpose of the study was to assess the relationship between
plasma haloperidol and clinical response. METHOD: 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.
