The biopharmaceutics classification system (BCS): Class III drugs - better candidates for BA/BE waiver?

Current guidelines (CPMP Note for Guidance in Europe and FDA Guidance for Industry in the USA) consider a waiver of bioavailability / bioequivalence studies for immediate release dosage forms of highly soluble, highly permeable drug substances (Class I according to the BCS). In this paper, a waiver of BA/BE studies is being proposed also for Class III compounds (high solubility and low permeability) in fast dissolving products without excipients which may modify gastro-intestinal transit or membrane permeation. This type of drug substance may be an even better candidate for a waiver as, in this case, bioavailability will not so much depend on the formulation characteristics, as on drug substance properties (e.g. permeability). (C) 1999 Published by Elsevier Science B.V. All rights reserved.