Preparation of 5-Aminosalicylic Acid-Loaded pH-Sensitive P(CE-MAA-EG) Microgels for the Treatment of Ulcerative Colitis

摘要

In this paper, a novel pH-sensitive poly(methoxyl ethylene glycol-caprolactone-co-methacrylic acid-co-poly(ethylene glycol) dimethacrylate) (P(CE-MAA-EG)) microgels were prepared via inversed-phase suspension polymerization method. The pH-sensitivity of the microgels was characterized. It could be seen that the microgels were shrinking in pH 1.2 and expanding in pH 7.4. Safety evaluation of the microgels was conducted by maximal tolerance dose (MTD) method. 5-Aminosalicylic acid (5-ASA) was loaded into the blank microgels, and the in vitro drug release behavior was also studied. The ulcerative colitis mice model was established using dextran sulfate sodium (DSS) as inducing agent. The 5-ASA/microgels were used to treat the ulcerative colitis mice, and free 5-ASA was used as positive control. On the 7th day, the mice were killed and the therapeutic effects of each groups were investigated. We could see that 5-ASA had good efficacy for treating ulcerative colitis and microgels entrapping 5-ASA could significantly enhance the colon-targeting to improve its efficacy. The animal test results showed that this 5-ASA/microgel might have great potential application in the treatment of ulcerative colitis.