Second International Pharmacological Meeting, Volume 4: Drugs and Enzymes is a collection of papers presented at the Second International Pharmacological Meeting on August 20-23, 1963. This volume is organized into two sections encompassing 41 chapters. The first section discusses the relationship between biochemical effects of drugs in vitro and their pharmacological effect in vivo. This section specifically examines the correlation between the action of substances on isolated smooth muscle and on the central nervous system, as well as the behavior of a centrally-acting drug and enzyme in the ion movement in the system. The second section surveys the biochemical mechanisms of drug toxicity. Considerable chapters in this section are devoted to the effect of drug toxicity, such as altered drug metabolism, enzyme induction, morphological changes, hepatic effects, and photosensitivity. This book will prove useful to pharmacologists, neurologists, biochemists, and researchers who are interested the fields of drugs and drug toxicity.