ABSTRACT
Objective: To prepare the pH dependent-microbially triggered colon targeted pellets of Rheum and optimize the preparation formulation of the targeted pellets. Methods: The pill-core was prepared by dropping preparation method, the pill-core fomulation was optimized by the orthogonal test, with drug loading, entrapment rate, and releasing rate as indexes. With release performance as index, the lagging cover weight increment was screened, the Rheum pellet that released at colon was obtained. Results: The 2% alginate-pectin solution, 0.7% chitosan solution, 1% CaCl2 solution, chitosan-CaCl2 solution with pH of 6.0, and the 4∶1 quantity of reagent (Rheum-accessory) were chosen as the top gallant fomulation to prepare the pill core, then enteric coating weight increased to 30% and the enteric coated-pellet was obtained. In gastric juice after 2 h and in small intestinal juice after 3 h, the coated pellet is cumulatively released to 2.01% and 8.72%, respectively, and released to 92.58% in the colon fluid after 4 h. Conclusion: The preparation fomulation of colon targeted pellet of Rheum is definited, and the colon targeted release is preliminary implemented.