Investigation of the colon-targeting, improvement on the side-effects and therapy on the experimental colitis in mouse of a resin microcapsule loading dexamethasone sodium phosphate

Context: Dexamethasone is the major drug in the treatment of ulcerative colitis (UC). However, the extensive or long-time use of dexamethasone causes many toxic side-effects. Ion exchange resins react with external-ions through their own functional groups and Eudragit S occurs degradation when pH>7. These features make them suitable for oral delivery system. Objective: Resin microcapsule (DRM) composed by 717 anion exchange resin and Eudragit S100 was used to target dexamethasone to the colon to improve its treatment effect on UC and reduce its toxic side-effects. Results: Dexamethasone sodium phosphate (DXSP) was sequentially encapsulated in 717 anion-exchange resin and Eudragit S100 to prepare the DXSP-loaded resin microcapsule (DXSP-DRM). The in vitro release study and in vivo study of pharmacokinetics and the intestinal drug residues in rat demonstrated the good colon-targeting of DXSP-DRM. Moreover, the DXSP-DRM can reduce the toxic side-effects induced by DXSP and have good therapeutic effects on colitis mouse induced by 2,4,6-trinitrobenzenesulfonic acid. Discussion: Dexamethasone can be targeted to the colon by DRM, thereby enhancing its treatment effect and reducing its toxic side effects. Conclusion: The resin microcapsule system has good colon-targeting and can be used in the development of colon-targeted preparations.