Designed as a textbook or reference, this work examines the use of drug serum concentrations, pharmacokinetics, and pharmacodynamics to individualize and optimize patient responses to drug therapy. It helps in understanding the merits, limitations, and applications of using serum drug concentrations in quantitative decision making. As a reference, this book discusses how drugs are monitored , the total laboratory testing process, test performance criteria, and outcomes of therapeutic drug monitoring (TDM) from system and patient related viewpoints. Each chapter contains a summary of important concepts as well as questions, answers and case studies.