Hepatic enzyme induction patterns and phenothiazine side effects.

D-Glucaric acid excretion was followed in psychotic patients treated with phenothiazines for 12 days and in a control group of subjects who had no psychiatric disease. About half the psychiatric patients had a treatment-related rise in D-glucaric acid excretion compatible with enzyme induction. These patients had fewer and less severe neurologic side effects than those who did not have a significant rise in urinary D-glucaric acid levels. It is concluded that individual differences in metabolism of phenothiazines may in part account for the variability in clinical response to these drugs.