Abstract
Abstract Poly (N-isopropylacrylamide) (PIPA) was grafted to polyallylamine hydrochloride (PA1Am • HCl) by amide formation under the influence of water soluble carbodiimide 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). The graft polymer was made into microspheres (MS) by chemical cross-linking. The pH responsive drug release of the graft polymer microspheres was examined by releasing phenobarbital natrium (PN) which was carried on the microspheres by physical adsorption. A dynamic dialysis technique was used in the drug release experiment and the drug release rate constants reflecting the drug release characteristic of polymer microspheres were obtained by constituting a mathematical model. The results indicated that the homopolymer PA1Am microspheres and the copolymer PA1Am-g-PIPA microspheres are both pH responsive to release PN and in neutral pH condition the release rate is the slowest.
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