Quantitative determination of nifedipine in human plasma by selected ion monitoring.

A highly sensitive and specific method for the determination of nifedipine in plasma is described. Nifedipine was oxidized to its pyridine analogue with nitrous acid and determined by selected ion monitoring. Deuterium labeled nifedipine was used as an internal standard. Plasma levels as low as 5 ng ml-1 were measured. The usefulness of the method was demonstrated by obtaining plasma concentration curves for humans after an oral dose of 10 mg.