Release performance of a poorly soluble drug from a novel: Eudragit (R)-based multi-unit erosion matrix

Mechanisms governing the release of drugs from controlled delivery systems are mainly diffusion, osmosis and erosion. For poorly soluble drugs, the ex isting mechanisms are limited to osmosis and matrix erosion, that are commo nly observed in single unit matrix dosage forms. This study reports formula tion and dissolution performance of Eudragit(R) L 100 55 and Eudragit(R) S 100 based multi-unit controlled release system of a poorly soluble thiazole based leukotriene D-4 antagonist, that was obtained by an extrusion/sphero nization technique. Effect of triethyl citrate, that was incorporated in th e matrix, on the dissolution performance of the drug was also evaluated. In vitro matrix erosion and drug release from the pellets were determined by the use of USP Dissolution Apparatus I, pH 6.8 phosphate buffer, gravimetry and UV spectrophotometry, respectively. Results obtained demonstrated that matrix erosion and drug release occurred simultaneously from the pellets. Pellets eroded with a consequent reduction in size without any change in th e pellet geometry for over 12 h. Matrix erosion and drug release followed z ero order kinetics. Data obtained strongly suggested a polymer controlled, surface erosion mechanism. (C) 2001 Elsevier Science B.V. All rights reserv ed.