Biopharmaceutics classification system

Biopharmaceutics Classification System (BCS) has provided a mechanistic framework for understanding the concept of drug absorption in terms of permeability and solubility. This article reviews the criteria and issues for classifying drugs according to the BCS. Biowaiver extensions for drug or active pharmaceutical ingredient from different BCS classes with scientific basis are discussed as the current BCS guidelines by World Health Organization, Unites State Food and Drug Administration and European Medicines Agency allows for biowaivers based on conservative criteria. The article sheds light on the possible new criteria and class boundaries proposed for additional biowaivers based on the underlying physiology of the gastrointestinal tract in required cases. The potential applications of BCS in drug discovery, drug delivery and drug research as well as extension for BCS are discussed. [PUBLICATION ABSTRACT]