The main goal of the pharmacokinetic modeling is the prediction of the drug concentration in the blood, tissues, and organs. The approaches to the modeling of physiological phenomena can be different on the basis of the details used to describe the Adsorption, Distribution, Metabolism, and Excretion (ADME) phenomena.

This review is focused on the state of the art in the pharmacokinetic modeling, on the different approaches used to describe the drug fate once it is administered. In particular, the early and the recent developments in the pharmacokinetic and in the gastrointestinal behavior modeling are discussed, together with some case histories of their applications.