Preparation of Colon-specific and Synchronous Release Pellet Containing Total Alkaloids of Sophora alopecuroides

Objective To deliver multiple component drugs to colon site and sustain a synchronous release for better therapeutic effect. For achieving this purpose, colon specific pellet containing total alkaloids of Sophora alopecuroides（TASA） was prepared. Methods The pellet was prepared by extrasion-spheronizing and subsequently coated with three layers of two polymers. Results The pellet core consisted of 40% TASA, 1:2 in ratio of Bletilla striata polysaccharide（BSP）, an enzyme-degradable material, to microcrystalline cellulose（MCC）, filler, and 1% CMC-Na solution as binder by optimization. Concerning of the three coated layers, the outer layer was coated with Eudragit RS30 D for controlling drug release in colon, the intermediate layer and the inner layer were coated with same polymer, Eudragit S100, for preventing drug release in upper gastrointestinal tract, which required 23.2%, 21.7%, and 9.3% weigh gain, respectively. The coated pellets released 1.20% of sophoridine and 1.98% of matrine in media mimicking the stomach condition for 2 h, and 23.88% of sophoridine and 22.91% of matrine in media mimicking the intestine for 3 h and finally 90.25% of sophoridine and 89.94% of matrine in colonic conditions within 24 h. And the similarity factor f2 of sophoridine and matrine of release curve for investigated formulation was internal in（50-100） and ＞ 80, demonstrating that sophoridine and matrine in formulation achieved a synchronous release. Conclusion The coated pellets achieve a certain colon-specific release and synchronous release.