Study of branched cationic β-cyclodextrin polymer/indomethacin complex and its release profile from alginate hydrogel

A series of branched cationic beta-cyclodextrin polymers (CP beta CDs) with designed chemical structures were synthesized from beta-cyclodextrin (beta-CD), epichlorohydrin (EP) and choline chloride (CC). Indomethacin (IDM), an anionic drug, was chosen as a model drug to evaluate the drug loading capacities of CP beta CDs. The formation of IDM-CP beta CD complex was confirmed by H-1 NMR and DSC. Phase solubility studies and job plots indicated that CP beta CDs can solubilize IDM up to 100 times of its intrinsic solubility in a 1:1 complexation form. Mechanism studies with the help of adamantane revealed that the effective complexation is a combination of inclusion complexation, charge interaction and hydrophobic interaction. In addition, IDM-CP beta CDs loaded alginate hydrogels were prepared and obtained controllable release profile in dissolution tests. The tunable structures of CP beta CDs make them promising drug carriers with superior drug loading capacities and controllable drug release abilities. (C) 2009 Elsevier B.V. All rights reserved.