ABSTRACT
The stability of a drug molecule in a marketed or to-be-marketed dosage form is always a concern to the people associated with the process. Most of the time, change in physical stability is an indirect effect of chemical stability and surfaces after chemical degradation takes place for some time. To define stability and to predict the shelf life of a dosage form, it is essential to determine the kinetics of the breakdown of the drug in the dosage form under projected usage conditions. This chapter examines pathways of drug degradation in pharmaceutical formulations by identifying the chemical groups present in classes of drugs that are particularly susceptible to chemical breakdown. In spite of most dosage forms on the market being solid or semisolid, there have been relatively few attempts to evaluate the detailed kinetics of the decomposition of such dosage forms.
