SWELLING-CONTROLLED RELEASE IN HYDROGEL MATRICES FOR ORAL ROUTE

This review focusses on hydrogel matrices or swelling-controlled delivery systems for drug delivery control mainly in oral use. The release mechanisms, modelling and mathematical analysis of release data are described, in order to show the dependence of the release kinetics on the movement of the fronts delimiting the undissolved core and the partially extracted region. Attention is directed to the movement of the relevant fronts of the matrix, in the knowledge that when synchronization of movement of the fronts can be achieved, constant drug delivery may be observed. Examples of hydrogel matrices in which the release behaviour is illustrated as a function of swelling behaviour are presented and discussed. In vitro-in vivo correlation obtained after the administration of the systems to human volunteers is also described.