Predictive models for oral drug absorption: from in silico methods to integrated dynamical models

Poor oral absorption is one of the most common reasons for a drug to be terminated during development. Oral drug absorption is a complex process affected by many competing factors related to the compound, the formulation and the gastrointestinal physiology. Throughout drug development, in silico, computational and mathematical models play important roles in the support of drug development and decision making in absorption-related issues. These models range from simple empirical rule of thumb tools to sophisticated dynamic systems. This article reviews the different computational methods for oral drug absorption for the various processes, with emphasis on solubility, permeability, dissolution and release rates, and gastrointestinal transit, but also on the modern integrated absorption prediction systems and computer software.