This book is focused on the principles and mechanisms of main drug degradation chemistry which are illustrated by representative examples reported in the literature. It will feature a collection of monographs for the degradation chemistry of ~350 small molecule drugs. The ~350 drugs are selected from a few sources such as the top 200 drug lists for the past few years, top selling prescription and OTC drug lists, WHO essential drug list and China's Basic Drug list. Each monograph is a concise summary of a drug's degradation chemistry and pathways reported in the literature with the authorÂs critical comments and discussion, if necessary. The focus of the degradation chemistry is placed on the "real life" degradation chemistry, that is, the degradation chemistry that tends to occur under long term stability storage conditions as opposed to artificial degradation that can happen under excessive forced degradation conditions. Although the main degradation chemistry described in the book would be chemical degradation occurred in drug substances and drug products (or in vitro degradation), certain in vivo degradation (or drug metabolism) that may be responsible for the toxicity, especially idiosyncratic toxicity of a drug will also be discussed. With the increasing regulatory requirements on drug quality and safety, which is often compromised by undesirable drug degradation, a book like this should have a wide readership in the pharmaceutical industry.