Chlorpromazine levels and the outcome of treatment in schizophrenic patients

P. R. May, T. Van Putten, D. J. Jenden, C. Yale and W. J. Dixon

Plasma and saliva levels of chlorpromazine hydrochloride were measured by gas chromatography-mass spectrometry, after a standard dosage had been administered to 48 newly admitted schizophrenic patients over 28 days. Other treatments were rigorously controlled. Saliva chlorpromazine concentrations were higher than plasma concentrations generally by about four to 50 times. Saliva and plasma chlorpromazine levels were significantly related. There was great variability in individuals between plasma and saliva peaks and values over time, in plasma/saliva ratios, and in change in plasma/saliva ratio over time. Chlorpromazine plasma and saliva levels at the end of fixed, sustained dosage treatment did not correlate with the amount of improvement as measured by ten criteria from the Brief Psychiatric Rating Scale and the Mobility, Affects Cooperation, and Communication Scale. Yet levels obtained in the 24 hours after the first dose did seen related to outcome, more strongly for saliva chlorpromazine than for plasma chlorpromazine levels. A reexamination is in order of our concepts of the relationships between levels of antipsychotic drugs in the body and treatment effect.