Defining the Pharmacodynamics and Pharmacokinetics of New Antiarrhythmic Drugs

Abstract

The time course of drug transit through the body and the time course of drug effect are closely related phenomena. It is generally assumed that the intensity of the activity of an antiarrhythmic drug is a function of the drug’s concentration at an effector site in the myocardium, and that this effector site concentration is in equilibrium with the concentration of the drug in the blood. Therefore, studies to describe the time course of accumulation and disappearance of antiarrhythmic drugs in the blood are helpful in understanding the dynamics of antiarrhythmic drug action. Extensive studies are required to completely understand the pharmacokinetics and pharmacodynamics of drugs and to evaluate the physiologic and pathophysiologic changes which can influence them. However, the evaluation of a new antiarrhythmic drug does not require a complete understanding of all the factors which affect absorption and disposition. This discussion will focus on those aspects of pharmacokinetics and pharmacodynamics which are relevant to the evaluation of the clinical utility and efficacy of new antiarrhythmic drugs.