Fabrication of Shellac-Based Effervescent Floating Matrix Tablet as a Novel Carrier for Controlling of Drug Release

Abstract

The aim of this research was to elucidate the factors affecting drug release and buoyancy properties of effervescent shellac based matrix tablet. Theophylline was selected as a model drug and sodium bicarbonate was used as a gas forming agent. To fabricate floating matrix tablets, the model drug, gas forming agent and other excipients were blended, compressed and then annealed at 80C for 24 h. The factors affecting floating and drug release, including amount of SHL and gas forming agent were investigated. The result demonstrated that the hardness of all formulations before annealing was within the range of 60+10 N. After annealing process, the hardness was significantly increased especially for formulation containing high level of SHL. The hardness of tablets containing 55% w/w or more of SHL was more than 200 N. As increasing amount of SHL (> 35% w/w), the more sustained drug release was also observed. The results were agreed well with the increased hardness. In addition, the tablets containing 20% w/w or more of gas forming agent were floated in 0.1 N HCl for more than 10 h, suggesting the good buoyancy characteristic. The kinetics of drug release in 0.1N HCl for all formulations were both fitted with Higuchi model and power law equation model, suggesting that the main mechanism of drug release in 0.1N HCl was obeyed the diffusion process. The result from this research could provide the basic knowledge for fabricating of SHL-based floating matrix tablet through varying amount of SHL and gastric forming agent.