The single and multiple dose pharmacokinetics of nifedipine were examined in five patients taking the drug as part of protocol 81- H-159. This study demonstrates for the first time that nifedipine accumulates, in the body when administrated to typical patients in a conventional oral dosage schedule. We have shown that the serum nifedipine concentrations at steady state were, on average, 30% higher than the concentrations measured after the first dose. Because of accumulation, single dose pharmacokinetic and pharmacodynamic characteristics of nifedipine will, most likely, be dissimilar. It may be useful to utilize single dose kinetic parameter values to predict study state accumulation of nifedipine in future studies of nifedipine disposition and efficacy.
