Techniques in the Behavioral and Neural Sciences, Volume 12: Neglected Factors in Pharmacology and Neuroscience Research: Biopharmaceutics, Animal Characteristics, Maintenance, Testing Conditions can be used as reference in the improvement of test designs for biochemists and physiologists in the control of test conditions. The book is divided into five sections. The introduction deals with the uncertainty of animal characteristics and test conditions as hindrances to the development of general insight into biological regulatory mechanism. The first section discusses biopharmaceutics — the interaction of drugs when interacting with molecules or enzymes in sufficient concentration at a specific site of action. The second section reviews animal characteristics in terms of strain differences, sex differences, and changes during development and aging of the subject. The third section discusses the maintenance of experimental animals such as housing conditions, food composition, and water intake as these kinds of environmental factors may shape the phenotype and responsiveness of the experimental animal. The fourth section explains the testing conditions such as metabolic effects and drug interactions, anesthesia, stress, and even the effects on circadian rhythms. The last section is a discussion on the importance of experimental results. This section covers internal and external validities and statistical inference. The author concludes that the design of any experiment should include a power analysis so that reliable and valuable conclusions can follow. Biochemists, physiologists, pharmacokineticists, toxicologists, chemical researchers, and others for whom drugs are their main focus of study will find this book valuable.