ABSTRACT
In the pharmaceutical industry stability programs are usually applied at various stages of drug development. For example, at an early stage of drug development, a stability program is necessarily carried out to study the stability of bulk drug substances. The purpose is to evaluate excipient compatibility under various storage factors, such as heat, humidity, light, and container type. At a later stage it is required to conduct a stability program for the formulations used in preclinical and clinical studies to make sure the drug product is within USP-NF specifications during the entire study. For the proposed market formulation, a stability program is required to establish an expiration dating period applicable to all future batches of the drug product. For the production batches, it is a common practice to have a stability monitoring program in place to ensure that all drug characteristics remain within USP-NF specifications prior to the established expiration date. The success of a stability program requires an approved stability study protocol in which reasons for choosing an appropriate stability design should be described in detail. In addition, the 1987 FDA stability guideline indicates that a stability study protocol must describe: (a) how the stability study is to be designed and carried out, and (b) statistical methods to be used in analyzing the data. Since the design of a stability study is intended to establish an expiration dating period, the design should be chosen so that it can reduce bias and at the same time identify and control any expected or unexpected sources of variations. The goal for selection of an appropriate stability design is to improve the accuracy and precision of the established shelf-life.
