A compartmental absorption and transit model for estimating oral drug absorption

This report describes a compartmental absorption and transit model to estim ate the fraction of dose absorbed and the rate of drug absorption for passi vely transported drugs in immediate release products. The model considers s imultaneous small intestinal transit flow and drug absorption. Both analyti cal and numerical methods were utilized to solve the model equations. It wa s found that the fraction of dose absorbed can be estimated by F-a = 1 - (1 + 0.54 P-eff)(-7), where P-eff is the human effective permeability in cm/h . A good correlation was found between the fraction of dose absorbed and th e effective permeability for ten drugs covering a wide range of absorption characteristics. The model was able to explain the oral plasma concentratio n profiles of atenolol. (C) 1999 Elsevier Science B.V. All rights reserved.