The biopharmaceutical classification system-experimental model of prediction of drug bioavailability

The Biopharmaceutical Classification System (BCS) is based on solubility tests, correlating for certain drugs with their bioavailability in human body. It is widely used in design and development of innovation drugs, new dosage forms (permeability amplifiers), in clinical pharmacology (drug-drug, drug-food interaction) and also by regulation agencies of several countries as the scientific approach, for testing of waiver on bioavailability. The review considers modern concepts and theoretical bases for prediction of bioavailability according to BCS. It gives characteristics of fundamental parameters of the system: absorption number, solubility number and ratio of dose to the soluble part of the drug. Possible versions of BCS modification for its subsequent optimization are discussed.