Mathematical modelling of drug permeation through a swollen membrane

This work proposes two different mathematical models (linear and numerical) able to simulate the drug permeation through a swollen membrane sandwiched by two external layers (trilaminate system). Moreover, a solid drug dissol ution phenomenon in the donor compartment may be accounted for. Indeed, thi s is a situation that may often occur in permeation experiments. An insuffi cient stirring of the donor and of the receiver volume may give rise to two sandwiching layers and the target of a constant drug concentration in the donor compartment may be accomplished by putting a solid drug amount in the saturated donor solution. The linear model shows the advantage of having a n analytical expression which extremely simplifies the calculation of the d rug diffusion coefficient D inside the membrane. Its main drawback lies in the fact that it works only for thin trilaminate systems. The numerical mod el is more general than the linear one, as it works for all kind of trilami nate thickness and it may account for a solid powder dissolution in the don or compartment. Of course, it does not have an analytical solution and, thu s, the D determination is less easy to perform as the numerical model is mo re time consuming than the linear one. These two models are then compared w ith the classical approach developed by Flynn and Barrie in order to better define its validity limits. (C) 1999 Elsevier Science B.V. All rights rese rved.