Evaluation of crosslinked chitosan hydrogel beads as a carrier for prolonged delivery of diclofenac sodium: in vitro and in vivo studies.

Chitosan hydrogel beads containing diclofanac sodium were prepared using ionotropic gelation technique in which tripolyphosphate solution was used as a counterion. Chitosan molecular weight, tripolyphosphate concentration and crosslinking time were found to have an effect on the percentage of the drug loading. The loading efficiency of diclofenac sodium was very high (more than 90%). A longer-period of contact with the counterion ions decreased the efficiency of drug loading. The beads produced all had good spherical geometry. The beads showed a narrow size distribution in which 95% of the beads prepared were in the range of 2-3 mm. Comparison of release rate-time plots of dissolution data of marketed product with the newly developed dosage form indicated the ability of the later to sustain more diclofenac sodium release. The beads were evaluated for their bioavailability in six beagle dogs relative to the commercial enteric-coated Voltaren tablets. The in vivo availability study, reveled that the prepared beads filled in hard gelatin capsules had a 126.22% bioavailability relative to that of the commercial Voltaren tablets. The beads showed comparable pharmacokinetic parameters to that of the commercial tablets. The results suggested the possibility of producing a promising sustained drug delivery system for diclofenac sodium.