An integrated model for determining causes of poor oral drug absorption

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.