Acrylic polymers for colon-specific drug delivery

Acrylic polymers are widely used in specific delivery of drugs to the human colon, primarily in the form of enteric coating formulations. Over-the last decade new studies have been reported in which azo bond-containing polymers were developed and tested in vivo. In contrast to enteric coating polymers, which function primarily by protecting their drug load in the proximal sections of the alimentary canal, azo polymers are designed to function by specific enzymaticdegradation in the large intestine. Saccharide-containing polymers have also been developed for mucoadhesion and enzymatic (glycosidic) degradation. In this study, two series of hydrogels comprising different ratios of methacrylic acid and the acrylosaccharide monomer, 1-methacrylamido-1-deoxy-cellobiitol, were synthesized. The mechanical strength of the hydrogels was engineered either by crosslinking the copolymer with ethylene glycol dimethacrylate or by using a third comonomer, hydroxyethyl methacrylate. The physical properties of the hydrogels were assessed by measuring their swelling characteristics and their mechanical strength. Also, the hydrogels were loaded with a model drug (indomethacin) and its release kinetics were measured to account for the differences in their swelling properties. These studies were performed to define an acrylosaccharidic polymer with optimal swelling properties in order to serve as colon-specific drug carriers which will release the least amount of drug possible in the upper part of the gastro-intestinal tract and degrade specifically in the colon.