In vitro evaluations of konjac glucomannan and xanthan gum mixture as the sustained release material of matrix tablet

The objective of the present investigations was to develop sustained release matrix tablets with a mixture of the polysaccharides, konjac glucomannan (KGM) and xanthan gum (XG), as the sustained release material. A simple enzymatic procedure was selected to mimic the environment of colon in vitro assessments. The concentration of P-mannanase solution in mimic colon media was determined by comparing the hydrolytic ability of the mimic colon solution with that of 4% (w/v) rat cecal content media. In vitro, investigations were carried out to characterize the drug release process. The model drug cimetidine released from polysaccharides gel layer of matrix tablets over 10 h. It was shown that the synergistic interaction between konjac glucomannan and xanthan gum in the gel phase affects on the drug diffusion, which can effectively retard the drug release from the matrix tablets. Further research on the mixed polysaccharides indicated that there was a strong synergistic interaction between KGM and XG in solution and in the gel phase. The experimental results predicted that the polysaccharide mixtures of konjac glucomannan and xanthan gum has a good potential to be applied to sustained release drug delivery systems. (C) 2007 Elsevier Ltd. All rights reserved.