Evaluation of Chitosan Citrate Complexes as Matrices for Controlled Release Formulations Using a 3²full Factorial Design

Abstract

Chitosan citrate complexes of several viscocity grades were synthesized, isolated, purified and identified. These complexes were found to form viscous gels of varying viscosities, upon dispersion in water. The ability of these complexes in sustaining drug release from matrix tablets was evaluated using a two factor three level full factorial design with theophylline as the model drug. Viscosity and concentration of the polymer complexes were optimized to achieve the desired in-vitro release profile. In-vitro dissolution characteristics were evaluated in deionized water as the dissolution medium. Data were fit to a quadratic model and polynomial equations were generated and used to predict the optimum formulation composition with desired release characteristics. These complexes were found to be very effective in sustaining the release of theophylline and were directly compressible. The release mechanism appears to be diffusion controlled. Excellent correlation was obtained between predicted and actual release profiles of the optimum formula.