Preparation and in Vitro Evaluation of the Bioadhesive Cephalexin Sustained-release Tablets

Objective:To prepare the bioadhesive cephalexin sustained-release tablets and to evaluate its in vitro adhesion performance and release profiles.Methods: The formulation for preparing bioadhesive cephalexin sustained-release tablets was optimized by single-factor method.The adhesive force of the test tablets prepared by adopting the best formulation was measured by using the self-made adhesion device,and the releasing rates at 1,2,4 and 8 h were determined by basket method.The releasing mechanism of cephalexin from the tablets was established by equation fitting of releasing kinetic model.Results: The best formulation consisted the following:HPMC K15M (6 mg) as the matrix materials,carbopol (CP 971P,20 mg) as binding materials,Flowlac 100 (18 mg) as fillers,cephalexin(52.6 mg)and magnesium stearate(0.5 mg).The adhesive force of the test tablets was 54.7 g.The releasing rates at 1,2,4 and 8 h were 30%,50%,70% and more than 90%,respectively.The in vitro drug release conformed to Higuchi equation,and releasing mechanism was synergism of diffusion and erosion.Conclusion: The bioadhesive sustained-release tablets meet the general requirements of the design.