染料木素自微乳的大鼠在体肠吸收机制研究

目的：研究染料木素自微乳在大鼠的在体肠吸收机制。方法：采用大鼠在体肠回流装置，UV，HPLC分别测定酚红和染料木素的含量。考察药物浓度、pH、不同肠段及P-糖蛋白( P-gp)抑制剂维拉帕米对染料木素吸收的影响。结果：染料木素自微乳在药物浓度为0.05～0.5 g·L^-1和pH为5.4～7.8时小肠吸收速率常数K_a均无统计差异；各肠段的吸收速率常数K_a空肠>回肠>十二指肠>结肠，空肠与其他肠段有统计差异(P<0.05)；维拉帕米显著增加染料木素的肠吸收 (P<0.05)。结论：染料木素自微乳在大鼠肠道的吸收呈一级动力学过程,吸收机制为被动扩散，在整个肠段都有吸收，最佳吸收部位在空肠。药物吸收受P-糖蛋白外排影响,而 pH对药物吸收无显著影响。

Study on absorption mechanism of genistein self-microemulsifying system in rat intestines

OBJECTIVE: To investigate the absorption mechanism of genistein self-microemulsifying system in rat intestines. METHOD: The concentrations of phenol red and genistein by in situ perfusion in rats were determined by UV and HPLC, respectively. The effects of drug concentrations, pH, various intestinal segments and P-glycoprotein (P-gp) inhibitor verapamil on the absorption had been studied. RESULT: The absorption rate constant (Ka) of genistein had no significant difference at concentrations of 0.05-0.5 mg x mL(-1) and pH of 5.4-7.8 in perfusion. It was Ka of jejunum > ileum > duodenum > colon. The absorption of genistein in jejunum had significant difference (P < 0.05) compared with other parts of intestines. Ka was increased obviously when verapamil was coper-fused with genistein (P < 0. 05). CONCLUSION: The absorption of genistein self-microemulsifying system is a first order process with passive diffusion mechanism related to P-gp efflux. It can be absorbed at all segments of rat intestine, and the jejunum is the best absorption segment, pH had no special effect on the absorption of genistein self-microemulsifying system in rat intestine.