Liquid Chromatographic Method to Measure Thioridazine and its Active Metabolites in Plasma

: A liquid chromatographic method for the measurement of thioridazine, northioridazine, mesoridazine, and sulforidazine in biological samples is described. An alkaline aqueous to organic extraction procedure containing an evaporation step is used. The internal standard is 7-methoxy-chlorpromazine. The absolute limit of sensitivity is 5 ng of each drug in 1 ml of plasma. The coefficient of variation in routine use is of the order of 10 % both between runs, and within runs.