ENANTIOSELECTIVE DETERMINATION OF ISRADIPINE IN HUMAN SERUM USING CHIRAL STATIONARY-PHASE LIQUID-CHROMATOGRAPHY AND GAS-CHROMATOGRAPHY WITHNITROGEN-SELECTIVE DETECTION

rac-Isradipine is a dihydropyridine type calcium antagonist. Its calci um entry blocking effect is due primarily to the (+)-(S)-enantiomer. T his study describes a sensitive enantioselective method for the determ ination of isradipine in human serum. Following alkaline extraction in to hexane, the enantiomers of isradipine are separated quantitatively by high-performance liquid chromatography on a Chiralcel OJ column at 39 degrees C. The collected fractions were evaporated and assayed usin g capillary gas chromatography on a HP 50+ column with nitrogen select ive detection. Using 2.0 ml of serum, 0.7 nmol/l (0.26 ng/ml) of each enantiomer could be determined with acceptable precision. The method h as successfully been used to measure (+)-(S)- and (-)-(R)-isradipine c oncentrations in samples from volunteers after intravenous and oral ad ministration of isradipine. (C) 1998 Wiley-Liss, Inc.