Am J Psychiatry 1976; 133:646-652
Copyright © 1976 by American Psychiatric Association
Clinical response and plasma levels: effect of dose, dosage schedules, and drug interactions on plasma chlorpromazine levels
L Rivera-Calimlim, H Nasrallah, J Strauss and L Lasagna
Plasma chlorpromazine (CPZ) levels of 50 psychotic inpatients were measured
by gas liquid chromatography; the clinical progress of 29 of these patients
with acute psychoses was also assessed. CPZ levels of 50- 300 ng/ml were
usually associated with clinical improvement; there was also a relationship
between CPZ levels and increases in certain symptoms. The 50-300 ng/ml
level was best attained by doses of 400-800 mg/day. Trihexyphenidyl
decreased plasma CPZ by a mean of 44.7% in 12 of 15 patients. A single
400-800-mg dose of CPZ at bedtime produced steady states equal to or better
than those achieved with multiple doses. Those patients who failed to
attain CPZ levels of more than 70 ng/ml despite doses of 400-1000 mg/day
were receiving lithium throughout the study and had discharge diagnoses of
manic-depressive psychosis, manic type, and schizo-affective
schizophrenia--a finding with implications for future research.
