The controlled release of blue dextran from alginate beads

Abstract

The purpose of this paper is to explore the possible applicability of alginate gel beads as an oral controlled release system of macromolecular drugs. Blue dextran (M.W. approx. 2000000) was used as the model of macromolecular drugs. The release of blue dextran from alginate beads was strongly affected by drying time and blue dextran/sodium alginate ratio. However, the release was not particularly affected by the other factors such as sodium alginate concentration, calcium chloride concentration, curing time, and drop size. The drug release from alginate beads at pH 6.8 showed nearly zero-order release rate, which was more rapid than that at pH 1.2. Since the release of blue dextran as the model of macromolecular drugs could be controlled by the regulation of the preparation conditions of alginate beads, the alginate beads may be used for a potential oral controlled release system of such macromolecular drugs as vaccines and polypeptide drugs.