Abstract: Physiologically based pharmacokinetic (PBPK) model is based on physiology, anatomy, enzymes for drug metabolism, characteristic of drug transport, physicochemical property of drug and drug-body interaction. Thus, PBPK model may quantitatively predict: concentration-time profiles of drug and its metabolites in plasma and tissues; pharmacokinetics of drug under disease status; pharmacokinetics of drug in special population; pharmacokinetics of drugs in human derived from experimental animals; in vivo pharmacokinetics of drugs based on in vitro parameters for metabolism and transport; pharmacokinetics of drugs from different formations; pharmacodynamics or toxicity of drugs based on in vitro parameters for metabolism, transport, activity or toxicity of drug; drug-drug interaction; individual contributions of enzymes and transporters to in vivo drug disposition. Here, we would review applications of PBPK model in drug development and several questions which should be thought through a series of examples.

Key words: physiologically based pharmacokinetic model, interplay of enzymes and transporters, in vitro-in vivo correlation, drug-drug interaction, physiologically based pharmacokinetic-pharmacodynamic model