Preparation and some physicochemical properties of cross-linked poloxamer hydrogel spheres

The principal purpose of this paper is to report the preparation of cross-l inked poloxamer hydrogel spheres in an aqueous two-phase system without the use of organic solvent and additional emulsifier and physicochemical prope rties related to drug release. Poloxamer 188 was modified with methacryloyl chloride to obtain the polymerizable derivative (macromer). The aqueous so lution of the macromer was mixed with dextran/magnesium sulfate aqueous sol ution to form a water-in-water emulsion system. After polymerizing the macr omer in the dispersion phase, nonporous particles with a mean diameter of m icron level were prepared. Both the mean diameter and swelling ratio of sph eres can be tailored by varying the starting composition of the preparation s. The drug release experiments indicate that the release of vitamin B-12 e ntrapped in the spheres follows first-order kinetics.