The Ontogeny of Drug Disposition: Focus on Drug Absorption,Distribution,and Excretion *

Pharmacokinetics is the scientific discipline which attempts to quantitate the important, dynamic processes of drug absorption, distribution, metabolism, and excretion. In essence, pharmacokinetics focuses on describing, in very specific detail, the sojourn a drug takes once it enters the body. Unfortunately, researchers' understanding of the influence of age on the disposition characteristics of drug effect is very limited. These database limitations continue to compromise one's ability to design optimal dose regimens for the care of sick infants and children. Nevertheless, it is only with a clear understanding of the various influences age has on drug disposition that these very important, compromising limitations will be resolved. This overview will focus on the ontogenic basis of the pharmacokinetics of drug absorption, distribution, and excretion. The important aspects relevant to drug metabolism will be addressed in a companion paper of this workshop.