Studies on the drug release properties of polysaccharide multilayers encapsulated ibuprofen microparticles

Ibuprofen microcrystals sized between 5 and 40 ?m have been encapsulated with polyelectrolyte multilayers (PEM) for the purpose of controlled release. The encapsulation was accomplished by a novel coating technology based on layer-by-layer assembly of oppositely charged polyelectrolytes. The biocompatible polyelectrolytes including chitosan, dextran sulfate, carboxymethyl cellulose, and sodium alginate were used as coating materials to fabricate PEM capsules with varying shell thicknesses from 20 to 60 nm. UV spectroscopy was employed to monitor the drug release processes in both pH 1.4 and pH 7.4 solutions. It was found that the release of ibuprofen from these microcapsules is dependent on several parameters such as the crystal size, the PEM capsule thickness, and the solubility of the core material in the bulk solutions. Our results reveal that the polysaccharide capsules can substantially prolong the release time of the encapsulated drug crystals.