Physiologically based pharmacokinetic (PBPK) models are an effective tool to integrate information about the product characteristics, the physiology of the individual subject, and the variability among subjects within a population to simulate the absorption and subsequent systemic disposition of the drug without conducting in vivo pharmacokinetic studies. These PBPK models have shown promise in supporting generic drug development and regulatory decision making. This opportunity solicits research proposals to expand the application of oral PBPK models to emerging issues in generic drug fields by providing the ability to simulate bioequivalence studies under various conditions.