Drug Release from Matrix Devices

Abstract

In general, the term matrix device implies a drug delivery system in which the drug is dispersed, either molecularly or as solid drug particles, within a polymer network. Within this context at least four different types of devices can be envisioned. These include: i) dissolved matrix devices wherein the drug is dissolved within a crosslinked polymer at or below the saturation solubility of drug in the polymer; ii) dispersed matrix devices in which drug is dispersed as discrete solid particles within a polymer such that the concentration of the drug far exceeds its saturation solubility in the polymer; iii) porous matrix devices which are analogous to dispersed devices except that the initial drug load is sufficient to produce contiguous channels throughout the polymer network; and iv) surface treated devices which have a core which is analogous to types i)–iii) and a surface layer which is of much lower permeability to the drug than is the core.