A mathematical model of drug absorption.

A model is presented which attempts to take into account the physical factors involved in intestinal drug absorption. The absorption rate is expressed in terms of the mass transfer resistance in the aqueous phase surrounding the drug particles and in the lipid phase of the membrane. The model provides a framework within which the effect of the various physical parameters of a drug on bioavailability may be considered. The experimental values of the constants in the model are shown to be of the same order of magnitude as those estimated from physiological and physical data.