PERCUTANEOUS-ABSORPTION - A MULTIPLE PATHWAY MODEL

The aim of this study is to present a mathematical model of percutaneo us absorption which considers the simultaneous penetration of drug by transcellular and intercellular pathways, as well as movement of drug between these two pathways. A two-layer mathematical model is formulat ed and solutions to this model are obtained numerically for data sets containing a range of physicochemical parameters relating to the percu taneous pathways and model drugs. Detailed graphical output is present ed of the drug concentration profiles with skin depth, the effect of l ipophilicity on steady state fluxes and the total amount of drug deliv ered, and the formation of drug depots within the skin. Many qualitati ve similarities exist between the multiple pathway model presented and previously proposed single and uncoupled pathway mathematical models. However, the model presented reveals effects of changes to the physic ochemical properties of the penetrant or the skin structure which are not shown with a single or uncoupled pathway model.