Preparation of Colon-targeting pH-Sensitive Hydrogel of Hydrocortisone Sodium Succinate and Experiment About Colon-targeting

OBJECTIVE To prepare the pH-sensitive colon-targeting hydrogel of hydrocortisone sodium succinate (HSS-GEL), and to explore its colon targeting. METHODS The preparation process of HSS-GEL was optimized by single factor method. HSS-GEL was prepared with konjac glucomannan (KGM), xanthan gum (XG) and sodium alginate (SA) as hydrogel materials, HSS as a model drug, and glycerol as a delayed release agent. The in vitro release of drug was used as an indicator to investigate the effect of glycerol and its dosage, materials ratio, preparation temperature and drug loading on the release of HSS-GEL. And the release characteristics in different pH media were investigated. The release of HSS-GEL in different tissue homogenates of rats' stomach, small intestine, blind colon and contents was investigated by hatching experiment, and the colon targeting was evaluated. RESULTS The optimal process was as follows:the ratio of KGM-XG-SA was 2.5:4:4, the amount of glycerin was 4% of the prescribed amount, and the preparation temperature was 70℃. The in vitro release results showed that the total release of HSS-GEL in PBS solution at pH 1.2 and pH 6.8 was ≤ 20%, that is, >80% of the drug could enter the medium of pH 7.4. The hatching experiment showed that the concentration of HSS in the blind colon was much larger than that in the stomach and small intestine within 1-10 h, which was greater than the sum of that in the two department at almost every point. CONCLUSION The preparation process of HSS-GEL is simple and stable, and the prepared HSS-GEL has good pH sensitivity and colon targeting.