Role of Decomposition on Drug Stability

Degradation and decomposition are interchangeably used in pharmaceutical sciences and are defined as the physical or chemical processes that lead the product to decline in its intended quality characteristics, which are claimed by the manufacturer. Both physical and chemical degradation reactions affect the stability of drugs. Physical degradation includes loss of water and volatile compounds, polymorphic changes, crystal growth, change in colour and water absorption. On the other hand, chemical degradation processes include hydrolysis, oxidation, decarboxylation, elimination, isomerization, dimerization, epimerization, photodegradation and dehydration. Various pharmaceutical dosage forms demonstrate different mechanisms of drug decomposition or degradation.