Targeted and controlled release of indomethacin from polyacrylic carrier systems

In this research work, a serious of prodrugs of poly(2-hydroxyethyl methacrylate) grafted with indomethacin were moddly synthesized and their chemical structures were characterized by FT-IR and 1H-NMR spectroscopy. The results showed that indomethacin was conjugated with polymer backbones through the ester bond. For in vitro experiment, the simulated medium for stomach, small intestine and colon was a chloric acid solution (pH 1.2), and a sodium phosphate buffer solution (pH 7.4 and 8.5). Detection of hydrolysis by UV spectroscopy at the wavelength of maximum absorption of the free indomethacin in the selected intervals showed that the drug was hardly released in the simulated stomach medium, but could be controlled release by hydrolysis of the polymeric prodrugs in the simulated small intestine and colonic conditions. Hydrophilic properties of polymeric prodrugs, as well as the reactivity of ester side groups used as weak links between the drug and the polyacrylic matrix, are considered on the basis of results obtained from in-vitro evaluation at different pH values.