Preparation and Properties of Enterosorbents Based on Carboxylated Microcrystalline Cellulose

Features of a non-traditional method of preparation of cellulose-based cation-exchange enterosorbents using nitrogen (IV) oxide are discussed. The proposed approach involves sequential use of oxidative and acid-hydrolyzing functions of nitrogen (IV) oxide to convert ordinary cellulose into carboxylated microcrystalline cellulose. X-ray phase analysis and transmission electron microscopy data show evidence of a topochemical character of cellulose microcrystal modification with carboxyl groups. Factors are indicated causing enhanced stability and whiteness of the samples thus obtained as compared with oxidized cellulose fibres, as well as the ease of stable tixotropic gel formation from the samples prepared in a salt form. Exemplified by methylene blue sorption, a comparative assessment of the sorptive ability of enterosorbent powders and hydrogels prepared in acid and salt forms. Results of clinical trials conducted with the gel enterosorbents in the areas of gastroenterology and detoxication therapy are presented. In view of compatibility of carboxylated microcrystalline cellulose in hydrogel form with many biologically active ingredients, prospective character of using the enterosorbents not only as such but also as a matrix for the development of new dosage forms of other medications is pointed out. Examples showing advantages of such combinations in specific sustained release drug forms (ointments and microgranules) are given.