Investigation of Prolonged Drug Release from Matrix Formulations of Chitosan

Abstract

A hydrocolloidal matrix system containing complexes of chitosan was investigated for preparation of sustained release tablets and examined in-vitro. Theophylline tablets using chitosan as a sustained release base were evaluated. It was found that when chitosan is used in a concentration of more than 50% of tablet weight, an insoluble non-erosion type matrix was formed. Tablets prepared with a chitosan concentration of less than 33% were fast releasing. Chitosan used in a concentration of about 10% acted as a disintegrant and the drug was dissolved within an hour. Citric acid slowed down the release rates of chitosan based theophylline tablets. Theophylline tablets using carbomer-934P as a sustained release base were evaluated. Carbomer-934P in lower concentrations forms an erosion type matrix. In order to produce a twenty-four (24) hour sustained release tablet, more than 10% concentration of carbomer-934P is needed. Combination with chitosan and carbomer-934P produced slower releasing tablets. A hydrocolloidal erosion type matrix was formulated using chitosan, carbomer-934Pand citric acid. Only 10% of chitosan was needed to prepare theophylline sustained release tablets in these mixtures. The dose dumping potential of chitosan tablets due to rapid disintegration in alkaline media was eliminated by preparing hydrated erosion type matrix systems.