Response in chronic schizophrenia correlated with chlorpromazine, 7-OH-chlorpromazine and chlorpromazine sulfoxide levels. 
The relationship between chlorpromazine, six of its metabolites and therapeutic response in chronic schizophrenic patients was investigated in this study.  Logistic regression revealed no correlation between therapeutic response and four metabolites viz.  Nor1 chlorpromazine, Nor2 chlorpromazine, chlorpromazine-N-oxide and Nor2 chlorpromazine sulfoxide.  A good correlation was seen between CPZ (P = 0.036), 7-hydroxychlorpromazine (P = 0.004), chlorpromazine sulfoxide (P = 0.002) and therapeutic response.  Good therapeutic response was correlated to high levels of chlorpromazine and its 7-hydroxy metabolite while high levels of the sulfoxide metabolite appeared to have a negative effect on therapeutic response.  Poor responders who had high levels of chlorpromazine also had high levels of the sulfoxide metabolite.  This suggests that the difference in response may lie in the difference in the metabolism of the drug.