目的为探讨穿心莲内酯生物利用度低的原因,考察穿心莲内酯肠道吸收特性,肝肠循环和肠道酶代谢特点。方法采用大鼠在体肠灌流模型。运用HPLC法测定肠灌流液、胆汁以及经肠道酶降解后样品中穿心莲内酯的量。结果穿心莲内酯在不同肠段的吸收率,以十二指肠最高,达40%,而在结肠最低,仅有10%。穿心莲内酯在十二指肠灌流液中的生物降解最显著(1 h降解约50%),在回肠、结肠中则几乎无降解反应。穿心莲内酯有胆汁排泄,其排泄量为灌流药物总量的0.76%。结论穿心莲内酯在大鼠肠道的吸收较差,而在十二指肠中吸收表现较好是由于存在较强的肠道酶代谢作用。同时,穿心莲内酯存在明显的肝肠循环。穿心莲内酯生物利用度低的原因与肠吸收差、肠道酶代谢作用强和肝肠循环有关。 Objective To investigate the reasons for the low bioavailability of andrographolide, and to investigate the characteristics of intestinal absorption, enterohepatic circulation and intestinal enzyme metabolism of andrographolide. Methods The rat model of intestinal perfusion was established. The amount of andrographolide in intestinal perfusate, bile, and intestine-degraded samples was determined by HPLC. Results The absorption rate of andrographolide in different segments of the intestine was the highest in the duodenum, reaching 40%, while the lowest in the colon was only 10%. Andrographolide showed the most significant biodegradation in duodenal perfusate (about 50% degradation at 1 h) and almost no degradation reaction in ileum and colon. Andrographolide has biliary excretion, its excretion is 0.76% of the total amount of perfusion drugs. Conclusion Andrographolide is poorly absorbed in the intestine of rats, while its absorption in the duodenum is better because of its strong intestinal enzyme metabolism. In the meantime, andrographolide has obvious enterohepatic circulation. The low bioavailability of andrographolide is related to poor intestinal absorption, strong intestinal enzyme metabolism and enterohepatic circulation.