CHITOSAN CALCIUM-ALGINATE BEADS FOR ORAL DELIVERY OF INSULIN/

A mild chitosan/calcium alginate microencapsulation process, as applie d to encapsulation of biological macromolecules such as albumin and in sulin, was investigated. The microcapsules were derived by adding drop wise a protein-containing sodium alginate mixture into a chitosan-CaCl 2 system. The beads containing a high concentration of entrapped bovin e serum albumin (BSA) as more than 70% of the initial concentration we re achieved via varying chitosan coat. It was observed that approximat ely 70% of the content is being released into Tris-HCl buffer, pH 7.4 within 24 h and no significant release of BSA was observed during trea tment with 0.1M HCl pH 1.2 for 4 h. But the acid-treated beads had rel eased almost all the entrapped protein into Tris-HCl pH 7.4 media with in 24 h. Instead of BSA, the insulin preload was found to be very low in the chitosan/calcium alginate system; the release characteristics w ere similar to that of BSA. From scanning electron microscopic studies , it appears that the chitosan modifies the alginate microspheres and subsequently the protein loading. The results indicate the possibility of modifying the formulation in order to obtain the desired controlle d release of bioactive peptides (insulin), for a convenient gastrointe stinal tract delivery system. (C) 1996 John Wiley & Sons, Inc.