AN INTRODUCTION TO DRUG DISPOSITION - THE BASIC PRINCIPLES OF ABSORPTION, DISTRIBUTION, METABOLISM, AND EXCRETION

A knowledge of the fate of a drug, its disposition (absorption, distri bution, metabolism, and excretion, known by the acronym ADME) and phar macokinetics (the mathematical description of the rates of these proce sses and of concentration-time relationships), plays a central role th roughout pharmaceutical research and development. These studies aid in the discovery and selection of new chemical entities, support safety assessment, and are critical in defining conditions for safe and effec tive use in patients. ADME studies provide the only basis for critical judgments from situations where the behavior of the drug is understoo d to those where it is unknown: this is most important in bridging fro m animal studies to the human situation. This presentation is intended to provide an introductory overview of the life cycle of a drug in th e animal body and indicates the significance of such information for a full understanding of mechanisms of action and toxicity.