High-performance liquid chromatographic method for the simultaneous determination of the enantiomers of carvedilol and its O-desmethyl metabolite in human plasma after chiral derivatization

Quantitative methodology for the simultaneous high-performance liquid chromatographic (HPLC) resolution and determination of the enantiomers of carvedilol, a new multiple-action antihypertensive agent exhibiting both vasodilator and beta-blocking activity, and its active metabolite, O-desmethylcarvedilol, in human plasma is described. The method involves reversed-phase solid-phase extraction of the analytes, followed by derivatization of the extract with the chiral reagent, 2,3,4,6,-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate and injection of the resultant diastereoisomers onto a reversed-phase HPLC column coupled to a fluorescence detector. Both pairs of diastereoisomers formed are completely resolved within 12 min (resolution for the respective pairs is 2.26 and 3.32) and the baseline is clean and free from extraneous peaks. The assay is linear over the range 0.6-80 ng/ml of human plasma with a lower limit of detection of approximately 100 pg on-column for each of the enantiomers. The method can be adapted for a number of structural analogues of carvedilol and is currently applied in support of preclinical and clinical studies of the drug.