A Novel Approach for Prediction of Intestinal Absorption of Drugs in Humans based on Hydrogen Bond Descriptors and Structural Similarity

A new approach to predict the intestinal absorption of drugs in humans is presented. It is based on structural similarity and hydrogen bonding properties (ΣC values) of drug-like compounds. The relationship between gastrointestinal absorption in humans and hydrogen bond descriptors for 100 structurally diverse drugs was studied. From the sigmoid relationship for passively transported drugs it could be concluded that those with ΣC values less than 14 were completely absorbed, whereas those with ΣC values higher than 18 were poorly absorbed. In cases where other transport mechanisms prevail due to special structural features, an absorption threshold can be significantly different. So, instead of including the whole set of compounds in the QSAR analyses, small subsets of 1 to 5 structurally related drugs (nearest neighbors of a drug of interest) estimated by means of similarity calculations were considered. The contribution of the passive transport component and the corresponding influence of hydrogen bond factors on absorption was assumed to be similar within the postulated subsets.