Purpose: To develop an integrated absorption model for estimating the fraction of dose absorbed and determining the causes of poor oral drug absorption.
Methods: Both analytical and numerical methods were used to estimate the fraction of dose absorbed.
Results: An integrated absorption model was developed by considering transit flow, dissolution, and permeation processes, simultaneously. A framework was proposed to determine permeability-, dissolution-, and solubility-limited absorption. Digoxin, griseofulvin, and panadiplon were employed to illustrate the applications of the integrated model in identifying the causes of poor absorption and guiding formulation development.
Conclusions: The integrated absorption model was successfully applied to digoxin, griseofulvin, and panadiplon to estimate the fraction dose absorbed and to roughly determine the causes of poor oral drug absorption.