Abstract

Purpose: To characterize the drug release behavior of three-layered tablets consisting of chitosan and xanthan gum. Methods: Three-layered tablets containing 1:1 chitosan and xanthan gum and 75% lactose were prepared by a direct compression technique to control the release of propranolol HCl. Drug release, water sorption and erosion behavior of the three-layered tablets in HCl buffer pH 1.2 and pH change were investigated. Drug release from one planar tablet surface was also investigated. Least squares fitting of the dissolution data to different mathematical equations was performed. Results: Barrier layers played an important role in controlling the drug release from the three-layered tablets. There was the lag-time for drug penetration through the hydrated barrier before diffusion into the dissolution medium. Dissolution profile fitting to mathematical release equations showed that almost all the drug release for both HCl buffer pH 1.2 and pH change exhibited near zero-order kinetic. Swelling and erosion in late stage of the drug release of polymeric components in the three-layered tablet corresponded to the drug release characteristics in different dissolution fluids. Conclusion: Water sorption and erosion behavior of the chitosan-xanthan gum matrix and also drug diffusion through the layered barrier affected the drug release from the three-layered tablets.


Keywords:  Drug release   Water sorption   Erosion   Three-layered matrix   Chitosan   Xanthan gum