Studies On Diclofenac Sodium Chitosan/alginate Sustained-release Microspheres And Evaluation Of In Vivo-in Vitro Correlation

As new oral sustained release carrier, alginate gel has been highly recommended to controlled-release of many drugs. In this paper, diclofenac sodium (DFS) was chosen as model drug to prepare calcium alginate gel microspheres and chitosan-alginate sustained release microspheres. Release characteristics were investigated respectively in order to obtain new sustained-release dosage form with little gastro-intestinal tract irritation.Plackett-Burman screening design was adopted in this paper to screen several factors affecting drug release in vitro of calcium alginate gel microspheres. Results of forward step wise regression analysis verified that dissolution media, the ratio of polymer to drug and concentration of CaCl₂ have significant effect on drug release behavior (p<0.05). Drug release in high pH environment was much faster than that in low pH.To obtain expected sustained-release, chitosan/alginate microspheres were prepared. Results of dissolution test demonstrated that addition of chitosan controlled drug release effectively. Polymer to drug ratio, concentration of CaCl₂ and chitosan influenced drug release greatly. pH value of dissolution media had great effect on drug release rate. The control ability of microspheres made by two steps method was higher than that by one step...