N-Carboxymethyl chitosan (NCMC) is a water soluble derivative of chitosan. The NCMC beads were prepared by using ionotropic gelation process with the counter polyanion tripolyphoshate at pH 4.0 and characterized by scanning electron microscopy. The swelling behavior of the beads at different time intervals was monitored at different pH conditions. The in vitro drug release behavior in various pH solutions was studied using indomethacin as a model drug with two different concentrations (0.3 and 0.6% w/w). The release percent of indomethacin from NCMC beads was found to increase with increasing of pH in phosphate buffer solution medium due to the ionization of carboxymethyl group and high solubility of indomethacin in alkaline medium. These results indicated that the NCMC beads are useful for controlled drug delivery systems through oral administration by avoiding the drug release in the highly acidic gastric fluid region of the stomach.
Dr. Jayakumar Rangasamy, Reis, R. L., and Mano, J. F., “Synthesis of N-Carboxymethyl Chitosan Beads for Controlled Drug Delivery Applications”, in Advanced Materials Forum III, 2006.