Xanthan-g-poly(acrylamide): Microwave-assisted synthesis, characterization and in vitro release behavior

Xanthan-g-poly(acrylamide) was synthesized employing microwave-assisted and ceric-induced graft copolymerization, and was characterized by FT-IR, DSC, XRD and SEM studies. Matrix tablets of diclofenac sodium were formulated using graft copolymer as the matrix by direct compression technique. Release behavior of the graft copolymer was evaluated using USP type-II dissolution apparatus in 900 ml of phosphate buffer (pH 6.8), maintained at 37 °C and at 50 rpm. Microwave-assisted grafting provided graft copolymer with higher % grafting in a shorter time in comparison to the ceric-induced grafting. The % grafting was found to increase with the increase in the power of microwave and/or time of exposure. The matrix tablets were found to release the drug by zero-order kinetics, and the faster release of drug was observed from the graft copolymer matrix as compared to the xanthan gum matrix. It was observed that grafting reduces the swelling, but increases the erosion of xanthan gum.