The Study On Chitosan/poly(vinyl Alcohol) Thermosensitive Hydrogel Drug Delivery System

In this study, using 5-fluorouracil as a model drug, a chitosan/poly(vinyl alcohol) thermo-sensitive hydrogel drug delivery system has been prepared by physico-mixing the chitosan and poly(vinyl alcohol). Also, the properties of the gels and the in vitro drug release behaviors were investigated in detail. As the easy operation, mild condition, simple formulation and no cross-linking agent in this method, it is a potential drug delivery system.The concentrations of NaHCO₃, CS and PVA were changed to inspect the gel temperature. It has been indicated that the gel can form when the concentration scope of NaHCO₃ was 0.40-0.55 mol/L and CS was 1.2-2.0 %. With the increasing of the concentration of NaHCO₃ and CS, the gel temperature degraded. To the gel temperature below 37℃of the formulation, with the increasing of the concentration of NaHCO₃ and CS, the gel time has been shortened. The pH value of the sol was controlled at 7.0. It has been illustrated that the PVA molecules only physically entangled inside the CS networks by IR. The SEM micrographs showed that all the gels had porous structures and the structure of the drug loaded hydrogel was more compact than the blank. The erosion behavior indicated that the concentrations of NaHCO₃, CS and PVA had influence on the erosion of the gel. The erosion rate was the lowest when the formulation was NaHCO₃ 0.52 mol/L, CS 2.0 % and PVA 1.0 %. The in vitro drug release behavior illustrated that the hydrogel had a sustained effect on 5-Fu in pH 7.4 PBS at 37℃. The drug release rate decreased with the increasing of the drug loading amount. The drug release behavior of each formulation had relationship with the microstructures of the gels.