Aspects of the clinical pharmacology of nifedipine, a dihydropyridine calcium-entry antagonist.

Although nifedipine has been characterized in terms of its general vasodilatory effects, this dihydropyridine must still be regarded as investigational with regard to available pharmacokinetic and pharmacodynamic data. Although limited studies are available, it is clear that the pharmacokinetic and pharmacodynamic data reported are quite variable among subjects. Further, it appears that single dose elimination kinetics may be of little predictive value with regard to the kinetic characteristics present during chronic drug administration. It is also possible that the plasma level-effect correlations for the drug may differ with single and sustained dosing regimens. At the present time the lack of definitive data to define the relationships between plasma levels of nifedipine and associated drug effects suggests that measurement of drug levels in plasma serves primarily as a research tool and to identify patient noncompliance or abnormal absorption of the drug. Finally, since the prototype of this class, nifedipine, has been shown to have the potential for non-linear kinetics during chronic dosing, dihydropyridine analogs should be subject to extensive pharmacokinetic and pharmacologic evaluation during both single and chronic dosing studies, prior to widespread clinical use.