Nifedipine kinetics and dynamics in hypertensive patients: a new approach

Nifedipine tablet in a 20 mg dose was administered orally to 44 patients with arterial hypertension. Nifedipine pharmacokinetics showed wide interindividual variation, for instance maximal concentration varied from 10-90 ng/ml, elimination half-life from 2-9 hours, etc. Cluster analysis classified all variants of nifedipine concentration profiles into 3 more homogeneous groups. Group A was characterized by small maximal nifedipine concentrations and its fast elimination; in group C nifedipine concentration reached high level in plasma and elimination half-life was more than 5.5 hours; in group B intermediate variants of nifedipine concentration profiles were separated. Nifedipine effects on mean blood pressure and platelet aggregation differed between these groups significantly. There were no changes in these parameters in patients from group A whereas in group C nifedipine produced profound and long-term reduction of both blood pressure and platelet aggregation. Using cluster analysis it appears to be possible to objectively classify a variant of nifedipine concentration profile to one of these homogeneous groups using only 3 measurements of nifedipine concentration in plasma at 1, 2 and 3 hours after the administration. It has been suggested that this approach simplifies the estimation of nifedipine pharmacokinetics and it might be useful for introducing the pharmacokinetic investigations to clinical practice.