Stability and bioequivalence challenges in generic drug formulation: A regulatory perspective

The testing of generic remedies is of great importance for welcoming affordable health care and the brand names. However, attaining the stability of a product and proving bioequivalence (BE) to reference medicines constitute a couple of the major formulation challenges toward the safety, efficacy, and quality assurance of generics. This paper takes a regulatory perspective to discuss these challenges comprehensively, thereby laying out the science, technology, and compliance principles facing generic drug developers. Stability is challenged by interactivity among APIs, excipients, and environmental conditions, with robust formulation and stability-indicating testing strategies envisaged for all possibilities. Bioequivalence studies also constitute one of the major hurdles for regulatory approval, thereby posing further design-specific challenges, such as variable absorption and differing effects of formulations, especially with modified-release formulations or when it comes to drugs with a narrow therapeutic index. Although regulatory expectations on stability data and BE demonstration as enforced by the FDA, EMA, and WHO are rigorous, in practice the differences in requirements between jurisdictions can impede submissions on an international level. Many avenues of emerging concern, focusing on the subjects of complex generics, the biowaiver, and regulatory harmony, are considered within the scope of the article.