A Study on Protein Binding of Nifedipine, Nilvadipine, Nicardipine and Nisoldipine

The protein binding parameters of four dihydropyridine calcium antagonists; nifedipine, nilvadipine, nicardipine andnisoldipine to purified human serum albumin (HSA) and α1-acid glycoprotein (AAG) were examined using ultracentrifugation. The four dihydropyridine calcium antagonists were predominantly bound to HSA and AAG. Nilvadipine showed the highest affinity to both HSA and AAG among the four dihydro-pyridine calcium antagonists.In HSA solution (40g·L-1) the mean bound fractions of the four dihydropyridine calcium antagonists did not differ from those reported in serum, suggesting that HSA is the major binding protein for nifedipine, nilvadipine, nicardipine and nisoldipine in serum. A slight difference was observed in the stereoselective binding of nilvadipine and nicardipine to HSA.