The controlled release of a drug from biodegradable chitosan gel beads

Chitosan (CS) forms a gel in solutions with a pH above 12, and the gelation occurs at pH of about 9 in 10% amino acid solutions. In this paper, we inv estigated the enzymatic degradation and the drug release profile of this no vel CS gel beads. The degradability of the CS gel beads was affected by the CS properties, e.g. the degree of deacetylation, The release of prednisolo ne (PS), as a model drug, from the CS gel beads was sustained significantly compared with the gel prepared with NaOH only. However, the release was no t able to be sustained by the increment of NaOH concentration in the soluti on employed for the preparation of CS gel beads. We also investigated the c ontrol of drug release from CS gel beads by application of a complex formed between chondroitin sulfate (Cho) and CS, The release of PS from the CS ge l beads treated with Cho was prolonged, and the release pattern was not aff ected by the treatment time. The time to 50% drug release was about 5 min w ith PS powder, about 200 min in CS gel beads with 10% glycine (Gly) (pH 9.0 ), and about 330 min in the CS gel beads with 10% Gly (pH 9.0) treated with Cho, Thus CS gel beads appear promising as a vehicle for sustained drug de livery, and the degradation of CS gel beads may be controlled by the degree of deacetylation of CS.