NIFEDIPINE KINETICS AND DYNAMICS IN HYPERTENSIVE PATIENTS - A NEW APPROACH

Nifedipine tablet in a 20 mg dose was administered orally to 44 patien ts 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 max imal nifedipine concentrations and its fast elimination; in group C ni fedipine concentration reached high level in plasma and elimination ha lf-life was more than 5.5 hours; in group B intermediate variants of n ifedipine concentration profiles were separated. Nifedipine effects on mean blood pressure and platelet aggregation differed between these g roups significantly. There were no changes in these parameters in pati ents from group A whereas in group C nifedipine produced profound and long-term reduction of both blood pressure and platelet aggregation. U sing cluster analysis it appears to be possible to objectively classif y a variant of nifedipine concentration profile to one of these homoge neous groups using only 3 measurements of nifedipine concentration in plasma at 1, 2 and 3 hours after the administration. It has been sugge sted that this approach simplifies the estimation of nifedipine pharma cokinetics and it might be useful for introducing the pharmacokinetic investigations to clinical practice.