Gas chromatographic mass spectrometric identification of O-demethylated and mono-hydroxylated metabolites of levomepromazine in blood from psychiatric patients by selected ion recording with high resolution.

An O-demethylated and two mono-hydroxylated metabolites of levomepromazine have previously been identified as conjugates in the urine from psychiatric patients. The three metabolites were identified in hydrolysed and nonhydrolysed plasma and erythrocytes from three patients by selected ion monitoring of the trimethylsilyl derivatives, with a mass spectrometric resolution of 5000. The three metabolites were mainly found as conjugates in the plasma, and smaller amounts were found unconjugated in the plasma and the erythrocytes.