Measurement of Plasma and Erythrocyte Chlorpromazine and N‐Monodesmethylchlorpromazine Levels by Gas Chromatography with a Nitrogen Sensitive Detector

Abstract

A new gas chromatographic method, employing a nitrogenphorphorus sensitive detector, for measurement of chlorpromazine and N-monodesmethylchlorpromazine is described. Application of the method to measurement of drugs in clinical [human] plasma and erythrocyte samples is demonstrated. The chlorpromazine concentration in erythrocytes is positively and linearly correlated with plasma drug level. A 4-fold inter-individual variation in the erythrocyte/plasma concentration ratios was evident. The concentration of the metabolite in the erythrocytes apparently was up to 27% of that of the parent compound. Chlorpromazine was unstable in plasma but stable in erythrocytes during a week''s storage in the dark at -20.degree. C. Possible clinical implications of these findings are discussed.