Preparation Of Colon Targeted Compound Rhubarb Double-coated Tablet And Its Quality Evaluation

Oral colon-delivery system is through oral administration but drug begins to release at ileocecus and act medicinally at colon. Aiming at Colon constipation, an effective cure in clinical use Rhubarb was researched on. According to the property of Rhubarb, the orthogonal test was designed to determine the best process of extraction by ethanol. That is eight times the amount of 80% ethanol 2nd 2 hours each. Considering the cost and safety of licorice, the orthogonal test was designed; the optimum conditions uses 10 times water to boiling with 2 times, 1 hour and 2hours respectively. We established the quality standard of Rhubarb, Emodin was determined by UV-spectrophotometric method, with a use of ether extraction, and colorimetric method by magnesium acetate methanol solution.Study shows that the standard curve presents a fine linear relationship within the quality range of 6.06～30.3μg/mL.Design by using three kinds of coating materials, and through the quality assessed of coated tablets to determine the best method. Seperately use chitosan and Eudragit S100 solution for coating, 10 layers. The disintegration study shows that the former can not achieve colon targeting, chitosan coated tablets collapse and release all drugs within 2h in artificial gastric fluid (pH=1.2). The latter can achieve that goal, Eudragit S100 coated tablets can not collapse in artificial gastric fluid (pH=1.2) and small intestine fluid (pH=6.8), and quickly release the drug within 1h in colon fluid (pH=7.4). But patients with colon constipation pH value will decline in colon area. So in order to ensure the drug efficacy and full release, doubled-coated tablet was designed. The inter layer is chitosan, the outer layer is mixture of Eudragit S100 and L100, 10 layers respectively. By the experiments of simulating gastrointestinal tract environment in vitro, shows that double-coated tablets in gastric fluid have a good tolerance within 2h because of the enteric-coated films, and also have a good toletance in small intestine within 3h because chitosan layers can only be dissolved by the bacteria in colon area. After adding certain Lysozyme, chitosan layers were dissolved, because of the fast-release tablet core, drugs release quickly and play a role in colon, which turned out that such formulations are able to be colonic targeting.