Isotopic sensitivity in the microsomal oxidation of the dihydropyridine calcium entry blocker nifedipine.

J L Born, W M Hadley

Index: Chem. Res. Toxicol. 2(1) , 57-9, (1989)

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Abstract

The primary deuterium isotope effect on Vm for the microsomal oxidation of the dihydropyridine calcium entry blocker nifedipine [4-(2-nitrophenyl)-2,6-dimethyl-3,5- bis(methoxycarbonyl)-1,4-dihydropyridine] has been measured. The magnitude of the kinetic isotope effect, 6.7, suggests that the rate-limiting step in the mechanism of microsomal oxidation of nifedipine involves the loss of a hydrogen atom rather than nitrogen oxidation. Thus the microsomal oxidation of nifedipine is mechanistically different from that of other 1,4-dihydropyridines.