Chiral high-performance liquid chromatographic determination of oxprenolol in plasma

A sensitive, stereospecific high-performance liquid chromatographic assay for oxprenolol enantiomers in rat plasma was developed, using a chiral derivatization agent. Racemic oxprenolol and the internal standard (racemic propranolol) are extracted with dichloromethane after alkalinization of the plasma. Quantitation of R(+)- and S(-)-oxprenolol is based on derivatization with the chiral agent S(-)-1-(1-naphthyl)-ethyl isocyanate, followed by chromatographic separation on a C18 reversed-phase column, with fluorometric detection (excitation at 226 nm, emission at 333 nm). The assay is reproducible as judged by a coefficient of variation of less than 17.5% for both enantiomers at all concentrations used. Preliminary experiments in the rat demonstrate that the method is sufficiently sensitive for pharmacokinetic studies in that species.