SIMULTANEOUS DETERMINATION OF (R)-BREFANOLOL AND (S)-BREFANOLOL IN HUMAN PLASMA - HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY ON A CHIRAL STATIONARY-PHASE

A new method for the quantitative enantiospecific determination of racbrefanolol, a vasodilating beta-adrenoceptor blocking agent, in human plasma is described. After an alkaline liquid-liquid extraction from biological material and a preseparation on a silica gel column with fractional collection of the eluate, the separation of the underivatized enantiomers is performed by high-performance liquid chromatography on cellulose tris-4-methylbenzoic acid polymer coated on silica gel. The UV-absorbance of the eluate was monitored at 254 nm. Determination limits are 10 ng enantiomer per mi plasma and allow the performance of pharmacokinetic studies after the aimed therapeutic dosages.