Impregnation and release of aspirin from chitosan/poly(acrylic acid) graftcopolymer microspheres

The purpose of this study was to produce aspirin-impregnated microspheres o f chitosan/poly( acrylic acid) copolymer in order to evaluate the release c haracteristics as a function of pH, simulating the fluids in the gastrointe stinal tract. Chitosan microspheres were obtained by the coacervation-phase separation method, induced by the addition of a non-solvent (NaOH 2.0 M so lution). The microspheres were cross-linked with glutaraldehyde, reduced wi th sodium cianoborohydride and grafted with poly(acrylic acid). The impregn ation of aspirin into chitosan/poly(acrylic acid) copolymer microspheres wa s achieved by the dissolution of the drug in water: ethanol (2:1), which wa s adsorbed by the microspheres for 24 h at 25 degreesC. The efficiency of a spirin impregnation was high (similar to 94%). The approach employed herein in the production of aspirin-impregnated microspheres using chitosan/poly( acrylic acid) can be a suitable drug-release control system.