Chitosan-polycarbophil interpolyelectrolyte complex as a matrix former for controlled release of poorly water-soluble drugs I: in vitro evaluation

Purpose: It was previously shown in our laboratories that the interpolyelectrolyte complex between chitosan and polycarbophil has promise as a matrix former to control the release of water-soluble drugs. This study further investigates the applications of this polymeric complex to produce controlled release matrices for poorly water-soluble drugs. Methods: The swelling, erosion, and drug release performance of matrix-type tablets containing the chitosan-polycarbophil complex as matrix former was compared to those consisting of hydroxypropylmethylcellulose and a simple mixture of chitosan and polycarbophil powders. Results: The chitosan-polycarbophil complex matrices showed good swelling with relatively low erosion and slower drug release compared to those prepared from other polymeric materials. They also exhibited release exponent (n) values closer to unity and therefore to zero-order release compared to the other matrices. Conclusions: The chitosan-polycarbophil complex formed matrix-type tablets that controlled the release of poorly water-soluble drugs approaching zero-order kinetics. The mechanism of drug release was mainly diffusion from swollen systems.