Determination of isradipine and its pyridine metabolite in serum by capillary column gas chromatography with nitrogen-selective detection

A relatively simple, sensitive and precise gas chromatographic method for the determination of isradipine, a calcium antagonist of the dihydropyridine type, and its main metabolite in serum is described. Using a one-step extraction procedure, a wide-bore column and a nitrogen—phosphorus detector, a limit of quantitation of 0.5 and 2.0 n M for isradipine and the metabolite was found. No interferences from several drugs were observed. The method was successfully used in a pharmacokinetic study in hypertensive women during pregnancy.