Ca2+ ion cross-linked interpenetrating network matrix tablets of polyacrylamide-grafted-sodium alginate and sodium alginate for sustained release of diltiazem hydrochloride

Interpenetrating network (IPN) matrix tablets of diltiazem-HCl (DTZ) was prepared by wet granulation method using polyacrylamide-grafted-sodium alginate (PAam-g-SAL) co-polymer and sodium alginate (SAL) for sustained release of the drug. Formulation of IPN structure was examined using FTIR spectroscopy, and compatibility of the drug with the polymers was evaluated through FTIR, DSC, and XRD analyses. The effect of co-polymer/SAL ratios, drug load, and total polymer/calcium gluconate (CC) ratios on drug release in acidic and phosphate buffer solutions was investigated. The release of drug was controlled by the relative magnitude of swelling capacity of IPN matrix and viscosity of the gel formed following dissolution of the polymers. The swelling capacity of the matrix was governed by the formation of calcium alginate gel structure and the rigidity imparted by the co-polymer. The results indicated that IPN matrix tablets of PAam-g-SAL and SAL could be used for sustained release of DTZ. (C) 2010 Elsevier Ltd. All rights reserved.