Abstract
In order to control the release of mesalazine (MSZ) in the gastrointestinal tract to achieve better pharmacological effects in the colon, in this study, MSZ was added to hydroxypropyl-β-cyclodextrin (HP-β-CD) to form a water-soluble HP-β-CD/MSZ inclusion complex. Then, the inclusion compound was loaded into the structure of the bilayer polyelectrolyte complex microsphere formed by alginate (Alg), chitosan (Cs), and kappa carrageenan (κ-Car) as the hydrogel carrier, and the hydrogel beads with colon-specific release MSZ after oral administration were formed. The formed hydrogel beads have different swelling capabilities in different pH media and have the greatest swelling degree under pH 7.4. The encapsulation efficiency and drug loading of hydrogel beads can reach up to 83.23 and 18.31%, respectively, and the size of hydrogel beads can be reduced to less than 1 mm after drying, so that the size of oral administration can be reached. In vivo experiments also showed that the formed hydrogel beads had a better therapeutic effect on colitis than free drugs, and the microspheres were biodegradable, so the double-layer pH-sensitive microspheres could be effectively used in colon-targeting drug delivery.
Highlights
Ulcerative colitis (UC) is an incurable inflammatory disease of the colon with a rapid increase in incidence worldwide, and the risk of UC patients developing colon cancer has increased significantly (Si et al, 2016)
The solubilization effect of β-CD and HPβ-CD on MSZ was compared by a phase dissolution method, and it was found that the solubilization effect of HP-β-CD on MSZ was significantly better than β-CD
The Dextran sodium sulfate (DSS)-induced a series of symptoms, such as injury and inflammatory cell infiltration, were significantly reversed after administration of commercially available MSZ and treatment with the MSZ hydrogel, showing a morphological structure similar to that of healthy mouse tissue, which indicates epithelial repair and inflammation alleviation. These results indicate that MSZ ameliorated DSS-induced colitis in a mouse colitis model
Summary
Ulcerative colitis (UC) is an incurable inflammatory disease of the colon with a rapid increase in incidence worldwide, and the risk of UC patients developing colon cancer has increased significantly (Si et al, 2016). The therapeutic effect of MSZ is greatly limited due to its poor water solubility and a low dissolution rate, and MSZ is absorbed through the mucosa of the upper gastrointestinal tract (stomach and small intestine), which impairs its pharmacological effects in the colon and causes side effects, including nephrotic syndrome and hepatitis (Zou et al, 2005; Chen et al, 2012; Hu et al, 2012) It is Hydrogel and Colitis important to develop a new type of MSZ drug delivery system to maximize its therapeutic effect. HP-β-CD is a hydroxylated derivative of β-CD, with good biocompatibility, almost no hemolysis and nephrotoxicity, and due to its surface activity and cavity depth it can effectively improve the stability and solubility of MSZ (Tang et al, 2018)
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