Chitosan-silicate biocomposites to be used in modified drug release of 5-aminosalicylic acid (5-ASA)

Biocomposites of chitosan (CS) and montmorillonite (VHS) were prepared by solid-liquid interaction of the components. The resultant composites were characterized by thermal analysis and the cation exchange capacity of the clay mineral was compared to polysaccharide retention. The composites were loaded with 5-amino salicylic acid (5-ASA), comparing the drug loading capacity and drug release behavior with those of the interaction products prepared with the drug and chitosan or montmorillonite alone. The results showed that chitosan was effectively retained by montmorillonite particles through cation exchange. In comparison with interaction products prepared using the drug and the individual components, there was a synergic effect between the clay mineral and the polysaccharide regarding both their ability to retain drug molecules, and also the control of drug release in acidic medium. In particular, the 5-ASA/CS/VHS composites showed higher drug loading and slower drug release compared to both 5-ASA/VHS and 5-ASA/CS interaction products, with almost linear release profile throughout test. According to the results, biocomposites of chitosan and montmorillonite were promising supports for modified formulations of 5-amino salicylic acid. (C) 2010 Elsevier B.V. All rights reserved.