In vitro and in vivo application of pH-sensitive colon-targeting polysaccharide hydrogel used for ulcerative colitis therapy

The aim of this study was to prepare, characterize novel types of pH-sensitive konjac gum-xanthan gum-glycerol-sodium alginate hydrogel (KGM-XG-GLY-SA hydrogel) allowing for the site-specific delivering of drugs to the colon and evaluate its colon-targeting characteristic. In this study, hydrophilic drug of hydrocortisone sodium succinate (HSS) was chosen as a model drug and successfully loaded in hydrogel without any organic solvent. In vitro investigations were carried out to evaluate its release process. The drug-loaded hydrogel shown good sustained release property that drugs release from test hydrogel was minimal at pH 1.2 (2h, 23.40%), pH 6.8 (4h, 25.88%), and significantly higher (4h, 70.20%) at pH 7.4. It is clear that adding glycerol in hydrogel as hysteresis preparation prevented the rapid dissolution of material in the higher pH of the intestine. Thus ensuring a controlled release of the entrapped drug. We studied the colonic-targeting behavior, in vivo toxicity test, pharmacokinetic study, features to reduce drug toxicity, and therapeutic effect of experimental UC of this preparation. All the results in vitro were shown that the K (KGM-XG-GLY-SA) hydrogels with glycerol had a good colon-targeting characteristic. In addition, results in vivo were indicated that K (KGM-XG-GLY-SA) hydrogel were nontoxic, reduced the spleen and thymus index, and had an obvious effect on the treatment of UC. Therefore, all results suggested that the developed HSS/KGM-XG-GLY-SA hydrogel (HSS-GEL) with glycerol as a colon-targeting vector might have greatly potential application in the UC healing.