Thermosensitive injectable hydrogels from poly(N-isopropylacrylamide)-dextran aqueous solutions: Thermogelation and drug release properties

Novel injectable thermosensitive hydrogel formulations with improved both water retention (WR) and drug release profile were prepared by adding dextran (DXT) to poly(N-isopropylacrylamide) (PNIPAM) aqueous solutions as a remedy against the demixing/syneresis phenomenon. The addition of the hydrophilic polysaccharide improved the WR of the hydrogel at 37 degrees C from about 12% in the absence of DXT to about 40-55% out of the initial amount introduced, depending on both PNIPAM and DXT concentrations. Also, the 5-fluorouracil release experiments showed an appreciably reduced burst effect for the DXT-containing hydrogels. The shape of the release profiles revealed the presence of two stages, differing each other from the point of view of the drug release rate.