Micelles/sodium-alginate composite gel beads: A new matrix for oral drug delivery of indomethacin

Micelles/sodium-alginate composite gel beads (micelles/SA beads) were constructed from SA matrix and indomethacin (IND) loaded six-arm block copolymer poly(epsilon-caprolactone)-block-(dimethylamino)ethyl methacrylate (S(PCL-b-PDMA)(6)) micelles. The morphology, swelling property and drug loading level of the beads were investigated. The release behavior of IND from three matrices including micelles, SA beads and micelles/SA beads was evaluated at pH 1.2, 6.8 and 7.4, as well as in the simulated gastrointestinal (GI) tract. Significant differences in the release of IND from each matrix were observed in the acidic and near neutral pH fluids. The results suggested that IND could be protected by the micelles/SA beads from being released under acidic conditions in the stomach and would be mainly delivered to the small intestine and the colon. The release behavior was dependent on the initial concentrations of SA and calcium chloride (CaCl2) due to the different crosslinking densities. The results demonstrated that these micelles/SA beads could represent a promising oral drug delivery system for drugs with poor water solubility. (C) 2011 Elsevier Ltd. All rights reserved.