ENANTIOSELECTIVE DETERMINATION OF MIANSERIN AND ITS DESMETHYL METABOLITE IN PLASMA DURING TREATMENT OF DEPRESSED JAPANESE PATIENTS

A method for the analysis of the enantiomers of mianserin and its main metabolite desmethylmianserin in plasma using a chiral AGP high performance liquid chromatography column is described. In the majority of 66 depressed Japanese patients, the concentration of the more active S(+)mianserin was higher than that of the R(-)-enantiomer. The mean SIR ratio was 1.9 +/- 0.9 (SD) (range 0.5-4.8). The concentration of S(+)- varied between 19 and 223 nM, while that of the R(-)-mianserin varied between 14 and 72 nM. Among 42 of the 66 plasma samples in which the enantiomers of desmethylmianserin could be measured, the R-form predominated in all but one. S-Desmethylmianserin was in most of the samples present in concentrations of <10 nM (limit of detection). Analysis of the enantiomers of mianserin and desmethylmianserin might allow the establishment of a closer relationship between plasma levels and clinical effects.