Preparation of a prolonged release tablet of aspirin with chitosan.

Abstract

A prolonged release tablet of aspirin [an analgesic and antipyretic drug] was prepared by compressing aspirin agglomerated by massing with an acetic acid solution of chitosan. The parameters controlling the drug release rate were the chitosan content in the tablet, the physical state of chitosan used for granulation, i.e., liquid solution or gel, and the pH of the dissolution test solution. When the chitosan solution was used for agglomeration, the drug release rate of the resultant tablet was faster than when the gel was used. The drug release became more prolonged with increasing chitosan content in the tablet or with decreasing pH of the dissolution test solution. The drug release kinetics of the tablet after a short swelling period were represented by equation 10 in the text, which was derived by assuming that the tablet dimensions decreased isotropically during the dissolution. The decomposition rate of aspirin in the tablet stored at 37.degree. C and at R.H. [relative humidity] 75.1% was determined by the amount of water absorbed by the chitosan in the tablet, leading to zero order kinetics with respect to the aspirin.