Novel pH-responsive graft copolymer based on HPMC and poly(acrylamide) synthesised by microwave irradiation: application in controlled release of ornidazole

Herein, the microwave-assisted grafting method was employed for the development of a novel pH-responsive graft copolymer derived from polyacrylamide-modified hydroxypropyl methyl cellulose [g-HPMC (M)]. The synthesised copolymer has been used for in vitro sustained release of ornidazole. Various characterizations confirm the formation of graft copolymer. Swelling studies indicate the pH-dependent swelling behaviour, while deswelling studies suggest that g-HPMC (M) shows faster deswelling in response to change in pH and/temperature. The cell viability study signifies that g-HPMC (M) is cytocompatible. The in-vitro release study demonstrates that g-HPMC (M) delivers ornidazole specifically in the colon pH, without release of the drug in the acidic environment, ensuring g-HPMC (M) as an ideal candidate for orally administered colonic drug carriers. The kinetics and mechanism of drug release suggest that it follows a non-Fickian release mechanism.