This book presents a summary of the ways mass spectrometry is used in various stages of drug discovery and development including early support of medicinal chemistry, drug metabolism studies, distribution, degradation, and various development assays. The book includes a balance of basic and advanced information. Specific chapters relate to various stages in the process (e.g., discovery) as well as chapters on topics of current interest (lipidomics and SiRNA) are covered. Other topics covered include: MS metabolite identification techniques in drug discovery and drug development; Analysis of biological drugs, proteins and peptides; Analysis of drug impurities and degradants; Applications for biomarker discovery and analysis; Applications to support medicinal chemists; and Mass spectrometry for lipidomics applications