Regulatory aspects of drug stability studies

Abstract

The U.S. Pharmacopeia (USP) defines stability as the extent to which a product retains, within specified limits and throughout its period of storage and use (i.e., its shelf life), the same properties and characteristics that it possessed at the time of manufacture. Stability studies play a major role in determining shelf-life of the product, fixing storage conditions for the product. Stability studies in general are divided into long term, accelerated, stress testing. Long term stability studies are conducted at normal storage conditions of the pharmaceutical product. Accelerated studies are conducted at exaggerated storage conditions and useful in predicting the stability in normal storage conditions. Stress testing strictly cannot be considered as stability studies however, they are performed to identify degradation products, and thus provide insight into validation of analytical testing methods, that determines the stability of pharmaceutical products (e.g. photo-stability studies). Regulatory aspects of stability studies includes the selection of batches for performing stability studies, storage conditions for performing stability studies and their frequency, test to be performed to analyze the stability of the drug substance and drug product. Data generated from stability studies forms the basis for evaluating shelf-life and storage conditions for the pharmaceutical product. Thus, Stability studies ensures that right amount of drug is available to the patient throughout its shelf life, and it is the one of the important criterion to be satisfied for the registration/ obtaining license for marketing pharmaceuticals.