In vitro evaluation of chitosan coated- and uncoated-calcium alginate beads containing methyl salicylate-lactose physical mixture.

CONTEXT

Methyl salicylate-lactose physical mixture (1:1 and 1:1.5 ratios) was incorporated into calcium alginate beads by a coacervation method involving an ionotropic gelation/polyelectrolyte complexation approach.

OBJECTIVES

This study aims to determine the influence of chitosan coating over the beads on drug entrapment efficiency (DEE) and release characteristics in artificial saliva compared to that of the uncoated beads.

RESULTS AND DISCUSSION

Changes in formulation parameters (gelation time, concentrations of Ca(2+) and alginate) resulted in decrease in DEE of chitosan-uncoated beads (p < 0.05). This is due to the combined effects of drug leach-out from the physical mixture by Ca(2+) ions, alginate gel matrix cross-linking and free drug diffusion from chitosan-uncoated beads. However, an increment in the DEE was seen for chitosan-coated beads. A rapid drug release profile was noted for uncoated beads, but for chitosan-coated beads a sustained release profile was depicted depending upon the coating conditions. Chitosan-coated beads had reduced swelling and erosion properties and thus behaved as a physical barrier to drug release. Shifting from anomalous transport type to Fickian transport confirmed the formation of physical barrier onto chitosan-coated beads.

CONCLUSION

Calcium alginate beads could be used as a controlled-release system for methyl salicylate-lactose physical mixture.