SIMULTANEOUS DETERMINATION OF PROPRANOLOL AND 4-HYDROXYPROPRANOLOL ENANTIOMERS AFTER CHIRAL DERIVATIZATION USING REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A reversed-phase high-performance liquid chromatographic method is described, which allows the simultaneous quantification of propranolol and 4-hydroxypropranolol enantiomers in human plasma. After extraction from plasma (pH 10.5 ) using ethyl acetate, the enantiomers are derivatized with R-(+)-phenylethylisocyanate as chiral derivatization reagent and triethylamine as basic catalyst in chloroform. Ascorbic acid is used to prevent 4-hydroxypropranolol from oxidation during the extraction. Chromatographic separation on ODS columns and fluorescence detection (228 nm/> 340 nm) allows sensitive quantitation of all derivatives. Incubation of the plasma samples with β-glucuronidase/arylsulfatase and the use of the specific β-glucuronidase inhibitor saccharo-1,4-lactone allows the quantitation of both the sulfate and glucuronide conjugates of the enantiomers. The method was applied to human plasma samples from a subject after administration of 60 mg racemic propranolol three times daily. © 1990.