Assay of 7-hydroxychlorpromazine, and failure to detect more than small quantities, in plasma of responding schizophrenics

A method for the assay of 7-hydroxychlorpromazine in biological fluids is described. The stages of the method are extraction into ether, back extraction into acid, alkalinisation and further extraction into ether, evaporation of the extract to dryness, and gas-chromatography of the extracted material as a silylated derivative using conditions previously described for chlorpromazine. The method is applicable to certain other hydroxylated chlorpromazines, but it is not superior to existing methods for the assay of nonhydroxylated analogues. Only small quantities of 7-hydroxychlorpromazine were detected in the plasma of schizophrenics showing a satisfactory clinical response, even when the compound was present in urine, providing strong evidence that the presence of 7-hydroxychlorpromazine in blood is not a pre-requisite of successful therapy.