DIRECT ANALYSIS OF THE ENANTIOMERS OF MEXILETINE AND ITS METABOLITES IN PLASMA AND URINE USING AN HPLC-CSP

A high-performance liquid chromatographic assay has been developed for the quantification of the enantiomers of mexiletine and its four majo r metabolites, in plasma and in urine. Mexiletine and all metabolites were determined, after derivatization of mexiletine and its hydroxymet abolites, p-hydroxymexiletine and hydroxymethylmexiletine, using a Chi ralpak AD chiral stationary phase, based on a carbamoyl derivative of amylose. o-phthalaldehyde was chosen as derivatization reagent to incr ease the sensitivity of detection, to achieve separation of all compou nds in one chromatographic system, and to avoid interferences.