Simultaneous determination of d- and l-propranolol in human plasma by high-performance liquid chromatography

A method for the determination of d- and l-propranolol in human plasma is described. The method involves extraction of propranolol from plasma, and the formation of diastereomeric derivatives with the chiral reagent N-trifluoroacetyl-1-prolylchloride. Separation and quantitation of the diastereomeric propranolol derivatives are carried out by a reversed-phase high-performance liquid-chromatographic system with fluorimetric detection. The reproducibility in the determination of d- and l-propranolol in human plasma was 4.5% (relative standard deviation) at drug levels of 10 ng/ml. In two subjects who received a single 40-mg tablet of racemic propranolol the plasma levels of the d-isomer were lower than of the l-propranolol. The half-lives of d- and l-propranolol were similar.