Preparation and in Vitro Evaluation of Carboxymethyl Konjac Glucomannan Coated 5-Aminosalicylic Acid Tablets for Colonic Delivery

Konjac Glucomannan(KGM) was denatured by Carboxylmethylation to prepare Carboxymethyl konjac glucomannan(CMKGM) as coating material of 5-aminosalicylic acid(5-ASA) tablets. The 5-ASA release properties of the tablets were measured in vitro in the gastrointestinal tract simulation environment and in buffer solutions with beta-mannase of pH 6.8 at 37 +/- 0.5 degrees. The properties of the CMKGM were analyzed by FTIR spectra, viscosity measurement and swelling measurement. The integrality of the 5-ASA was investigated by ultraviolet spectrometry. The viscosity and swelling showed that CMKGM has lower swelling and lower viscosity compared to KGM. 5-ASA was released least in stimulating gastric environment and in pH 6.8 phosphate buffers,while the preparation was fast released in pH 6.8 phosphate buffers with beta-mannase. The preparation was released 14% after 4 hours in pH 6.8 phosphate buffers, at the same time the preparation in pH 6.8 phosphate buffers with 0.2u ml(-1) beta-mannase was released 97% in 12 hours. The results suggested that CMKGM may be a useful carrier of 5-ASA for colon-specific delivery. It has a potential use for advanced controlled release.