Liquid chromatographic analysis of promethazine and its major metabolites in human postmortem material

A method is described for the determination of promethazine and some of its major metabolites in postmortem specimens by enzymic digestion followed by high-pressure liquid chromatography of the extracts using a cyano-bonded (mu-Bondapak-CN) silica column packing and a mobile phase consisting of methanol, water, and n-octylamine (adjusted to pH 8). The system will separate and quantitate promethazine sulphoxide, desmonomethyl promethazine, didesmethyl promethazine, and promethazine. Pericyazine (2-cyano-10-[3-(4- hydroxypiperidino )propyl] phenothiazine) was used as internal standard. The parent drug and metabolites were extracted from a enzyme digested tissue homogenates with ethyl acetate using a simple, single micro-extraction procedure. The method was applied to four cases of fatal poisoning involving promethazine ingestion.