Butterworths International Medical Reviews, Clinical Pharmacology and Therapeutics 1: Presystemic Drug Elimination explores the principles of presystemic drug metabolism in human based on animal studies. This book is divided into four sections encompassing 10 chapters that specifically describe the extent of metabolism occurring in the gastrointestinal tract, liver, and lung. Section 1 focuses on presystemic elimination by the gastrointestinal tract. This section discusses the enzymatic biotransformation in the gastrointestinal mucosa and the ability of the microflora to metabolize drugs. Section 2 considers the contribution of the liver to presystemic drug elimination, with a particular emphasis on the physiological factors, which determine the rate of breakdown of drugs in vivo. This section also deals with the effects of hepatic cirrhosis on presystemic drug elimination. Section 3 presents first a brief outline of the knowledge of pulmonary structure and relevant physiology, followed by a discussion on "first-pass metabolism of endogenous substrates and drugs across the pulmonary circulation and of environmental chemicals after inhalation. This section also provides the methods for distinguishing between the contribution of the various sites to presystemic drug elimination and the problems associated with attempts to analyze available pharmacokinetic data. This work is an ideal source for clinical pharmacologists and researchers.