Polar molecular surface properties predict the intestinal absorption of drugs in humans

Purpose. A theoretical method has been devised for prediction of drug absorption after oral administration to humans. Methods. Twenty structurally diverse model drugs, ranging from 0.3 to 100% absorbed, were investigated. The compounds also displayed diversity in physicochemical properties such as lipophilicity, hydrogen bonding potential and molecular size. The dynamic molecular surface properties of the compounds were calculated, taking into account their three-dimensional shape and flexibility. Results. An excellent sigmoidal relationship was established between the absorbed fraction after oral administration to humans (FA) and the dynamic polar molecular surface area (PSA(d)) (r(2) = 0.94). The relationship was stronger than those obtained for more established predictors of drug absorption. Drugs that are completely absorbed (FA > 90%) had a PSA(d) less than or equal to 60 Angstrom(2) while drugs that are < 10% absorbed had a PSA(d) greater than or equal to 140 A(2). Conclusions. The results indicate that PSA(d) can be used to differentiate poorly absorbed drugs at an early stage of the drug discovery process.