Plasma concentrations of chlorpromazine (CPZ) and six metabolites were
measured in 12 chronic schizophrenic patients on a fixed dose of CPZ.
All six metabolites were measured in significant concentrations, rang
ing from 12 to 57% of the parent drug concentration. They are listed i
n order of decreasing mean concentration as follows: chlorpromazine-N-
oxide > chlorpromazine sulfoxide > 7-OH chlorpromazine > Nor(2) chlorp
romazine sulfoxide > Nor(2) chlorpromazine > Nor(1) chlorpromazine. CP
Z concentrations showed significant correlation with the 7-OH chlorpro
mazine metabolite concentration. Since these metabolites have been ass
ociated with in vitro activity and occur in significant concentrations
, it is recommended that all six metabolites be measured in studies co
rrelating drug levels with pharmacodynamic effects.