DRUG-RELEASE FROM CHITOSAN BEADS

In this study, chitosan beads containing sulphadiazine as a model drug were prepared by ionotropic gelation with tripolyphosphate ions. Bead s containing up to 90% w/w drug loading could be prepared by this meth od. The efficiency of drug loading, as well as bead size, opacity and sphericity, increased with drug loading. A longer period of contact wi th the counterions, however, decreased bead size and efficiency of dru g loading. Different drug release profiles were observed, depending on the drug loading in the beads and the dissolution medium used. In 0.1 M HCl, beads containing less than 34% w/w sulphadiazine showed a slow er rate of drug release with increasing sulphadiazine content. For bea ds containing a drug load of more than 33% w/w, the release mechanism after 100 min in the acid medium was predominated by polymer erosion. There was no apparent erosion of the chitosan beads in simulated intes tinal fluid.