Research On The Preparation And In Vitro/in Vivo Evaluation Of Compound Berberine Hydrochloride Colon Specific Tablets

The subject is to prepare the Enzyme-controlled Colon-Specific tablets of Berberine hydrochloride (BH) and Aucklandiae extract by using of modern preparation techniques based on the early related evaluation of efficacy. And to evaluate the release characters of the tablets in vitro/in vivo.The paper includes the following sections:Part 1 Summary of the related literaturesSummarizing the research progress in oral colon-specific drug delivery system (OCDDS) and the evaluation methods of OCDDS in vitro and in vivo. Studies on the pharmacokinetics of berberine in recent years were reviewed.Part 2 The preparation and in vitro evaluation of berberine hydrochloride and its compound Colon-Specific tabletsThe two colon-specific tablets were prepared by coating matrix core tablets with Eudragit L100 and S100. The core tablets, containing pectin and guar gum, were compressed and had a diameter of 3mm. Compared with compound BH colon specific tablets (Compound BH-CST), the BH colon specific tablets (BH-CST) didn't contain Aucklandiae extract instead of microcrystalline cellulose. The content of BH in two tablets was determined by HPLC. The linear range of berberine in the samples was 0.82～40.800mg·L-1, the standard curve was in good linearity (r>0.999), The recovery of the method was 98.6±2.3%(x±s, n=6), RSD<3% and the precision, repeatability and stability met the requirements. The content of BH in BH-CST and Compound BH-CST was 252.6 mg·g-1(n=6)and 269.6 mg-g-1(n=6 )respectively.In vitro release studies were carried out in simulated gastric fluid (SGF) of pH 1.2 for 2h, simulated intestinal fluid (SIF) of pH 6.8 for 3h, and simulated colonic fluid (SCF) of pH 5.8, with 0.5g·L-1pectinase and 0.5g·L-1β-mannanase present, for the duration of 6～12h. The release of berberine from the two tablets was only about 10% during the first 4h and was increased markly when the tablets were exposed to SCF, which containing pectinase and mannanase. The cumulative amount of berberine was released more than 90% during the first 9h, indicating that the ability of enzymes to degrade the pectin and guar gum formulated in the tablets and suggesting that this carrier can be used to deliver drugs to the colon.Part 3 The sthdy on drug release characters in rats' gastrointestinal tract of BH-CST and Compound BH-CSTThe rats were administrated orally with the two colon-specific tablets of diameter 3mm and BH suspension respectively. Various gastrointestinal contents and tissues were collected at different time points after administration. The GI tract was segmented into the stomach; proximal small intestine; distal small intestine; cecum and colon. The luminal contents and tissues were removed and prepared for detection. The concentration of berberine in those biosamples was determined by HPLC, using palmatine as internal standard. The relative methods were established. (1) The linear range of berberine in various gastrointestinal contents was 0.10～20.0mg·L-1 respectively, the standard curves were all in good linearity (r>0.999), The recovery of these methods was in the range 85%～115%; the intro-day and inter-day precision (RSD) were both less than 10% respectively; the repeatability and stability of the methods met the requirements. (2) The linear range of berberine in various gastrointestinal tissues was 0.05～10.00mg·L-1 respectively, the standard curves were in good linearity (r>0.999). The recovery of the method was in the range 85%～115%; the intro-day and inter-day precision (RSD) were both less than 10% respectively; the precision, repeatability and stability met the requirements. All the methods have been successfully applied to determine the berberine concentration in rats'gastrointestinal biosamples.Compared with BH group, which administrated BH suspension, there are some differences in vivo release characters of the two colon specific tablets as follows. (1) Berberine was not detected in rats'gastrointestinal contents and tissues of Compound/BH-CST groups during the first 2h. The release of the drug had begun about 4h in rats'distal small intestine. It specifically released markly in rats'caecum and colon between 4～6h. (2) The drug was not detected in rats'stomach and proximal small intestine of Compound/BH-CST groups within 22h, mainly distributed in rats'caecum and colon. (3) The content of berberine in rats'colon of BH- CST group and Compound BH- CST group was higher than that of BH group. The value of AUC0-22h in luminal contents of rats'colon was 5.1 times and 3.9 times of BH group respectively, and the value in rats'colon tissues was 2.7 times and 3.6 times of BH group respectively. Indicating that BH-CST and Compound BH- CST showed the release characters of OCDDSPart 4 The study on pharmacokinetics of berberine in rat plasma after oral administration of BH-CST and Compound BH-CSTThe berberine in rats' plasma was determined by RP-HPLC, on a ZORBAX SB-C18 column (250mm×4.6mm,5μm). The mobile phase was acetonitrile-water-0.033mol·L-1 KH2PO4 (29:71, pH 3.0) and the flow rate was 1.0mL·min-1. The UV detector was set at 345nm and the column temperature was at 30℃. The linear range of berberine in rat plasma was 0.02～0.40mg·L-1, the standard curve was in good linearity (r=0.9988), The recovery of the method was in the range 100.0～101.6%; the intro-day and inter-day precision (RSD) were both less than<10%; the repeatability and stability of the method met the requirements.The rats were administrated orally with the two colon-specific tablets of diameter 3mm and BH suspension respectively. Plasma samples were collected at different time points after administration. Berberine was not detected in rat plasma of the BH-CST group. The mean maximum plasma concentration (Cmax) in the Compound BH-CST group was about 0.25 mg·L-1 and Tmax was 6h, lower than BH group (Cmax=1.13mg·L-1, tmax= 2h) obviously. Compared with BH group, the DDI (drug delivery index) value of rat colon was 8.46,7.3 and 3.6 times of that in distal small intestine and caecum respectively. The results indicate that the pH- and enzyme-controlled Compound/BH colon specific tablet is a carrier for targeting the drug to the colon.In our study, the Compound BH colon-specific tablets were prepared using pectin and guar gum as matrix material. The method is simple and easily to realize in industry. It is useful in meeting conventional requirements of traditional Chinese clinical medicine. In vivo test, we detected the drug content in rats' luminal contents, gastrointestinal tissues and plasma within 22h, and evaluated the release characters of BH-CST comprehensively.