SERUM CONCENTRATIONS AND EFFECTS OF (+/-)-NICARDIPINE COMPARED WITH NIFEDIPINE IN A POPULATION OF HEALTHY-SUBJECTS

The dihydropyridine calcium antagonist (±)-nicardipine shares some of the pharmacologic properties of the dihydropyridine prototype nifedipine. To compare them, serum concentrations and cardiovascular effects of 10 mg nifedipine and 20 mg (±)-nicardipine were evaluated at 1, 2, and 3 hours after oral intake in a randomized, crossover, single-blind study involving 79 healthy volunteers. (±)-Nicardipine serum concentrations were much lower than those of nifedipine, indicating a greater hepatic first-pass metabolism of (±)-nicardipine. There was a significant correlation between serum concentrations of both drugs. The frequency distributions of nifedipine and (±)-nicardipine AUC(0-3), heart rate increase, and mean arterial pressure decrease showed no bimodality. This does not confirm the proposed polymorphism of nifedipine oxidation. Concentration-effect plots indicate that (±)-nicardipine is more potent than nifedipine but shows comparable efficacy in blood pressure reduction. © 1990.