Poly [(maleic acid)-co-(propane-1,2-diol)-ran- (citric acid)] for pH-Responsive Extended Drug Release

ABSTRACT: The Dean-Stark apparatus was used to synthesize poly[(maleic acid)-co-(propane-1,2-diol)-ran-(citric acid)] in xylene medium in presence of anhydrous FeCl3 catalyst. FTIR-spectrum, TGA, soil burial biodegradation test, molecular weights, solubility in common organic solvents, elemental analysis and hydrolytic degradation test were performed to characterize the synthesized co-polyester. Soil burial biodegradation study showed nearly complete miscibility of the co-polyester in soil within around 2 months. Hydrolytic degradation study in solutions of different pH values, at room temperature, showed that this co-polyester stayed practically intact in solutions of pH 1.2-6.0, but they steadily degraded in solutions of pH>7.0. Because of such pH-responsive degradation characteristics, this co-polyester was tried as a carrier of oral formulation for non-steroidal anti-inflammatory drugs. In simulated intestinal fluid, a constant rate of drug release (zero order) up to 10 hours from drug-loaded polymer matrix tablets was observed.