Various Types and Mechanisms of Degradation Reactions

Abstract

This chapter covers most commonly occurred drug degradation reactions, except for hydrolysis, oxidation, degradation caused by interaction with excipients, and photochemical degradation. The latter two categories of drug degradation will be discussed in Chapters 5 and 6, respectively. The degradation reactions covered in this chapter include elimination, decarboxylation, nucleophilic conjugate addition and its reverse process, aldol condensation and the retro-aldol process, rearrangement and isomerization, cyclization, dimerization and oligomerization, and a few examples of degradation via miscellaneous mechanisms and pathways. While some of the above classifications are relatively specific in their scope, for example, decarboxylation, nucleophilic conjugate addition, and aldol condensation, others are more complicated as they can involve many sub-types or different types of degradation pathways and mechanisms. For example, cyclization and dimerization can involve many different types of degradation mechanisms. More than 50 examples of drug degradation are discussed in this chapter.