尼群地平大鼠在体肠吸收动力学研究

 目的 研究尼群地平在大鼠各肠段的吸收动力学特征。方法 采用大鼠在体小肠回流实验装置，利用紫外分光光度法和HPLC分别测定酚红和尼群地平的含量。结果 尼群地平在十二指肠、空肠、回肠、结肠的吸收速率常数分别为0.061 2，0.047 7，0.041 1，0.035 8 h^-1；在小肠的吸收速率常数不同药物浓度5，10，15 μg·mL^-1时分别为0.101 1，0.108 6，0.108 5 h^-1；不同pH值6.4，6.9，7.4，7.9时分别为0.101 0，0.118 5，0.108 6，0.141 7 h^-1；增溶剂聚山梨酯80浓度0.3%，0.5%，1.0%时分别为0.107 8，0.108 6，0.102 3 h^-1。结论 不同的药物浓度、pH值和聚山梨酯80的浓度对尼群地平在大鼠全肠道的吸收无显著影响，药物的吸收呈一级动力学过程，吸收机制为被动扩散；尼群地平在各肠道均有较好的吸收，提示适于制备日服一次的缓释给药系统。

Studies on the intestinal absorption kinetics of nitrendipine in rats

OBJECTIVE To investigate the absorption kinetics of nitrendipine at different intestine segments in rats METHODS The intestine in rats was cannulated for in situ recirculation. UV and HPLC were used to determine the concentrations of phenolsulfonphthalein and nitrendipine, respectively RESULTS The absorption rate constants (Ka) at duodenum, jejunum, ileum, and colon were 0.061?2，0.047 7，0.041 1 and 0.035 8 h^-1 respectively. Ka from intestine at nitrendipine concentration of 5, 10, 15 μg·mL^-1 were 0.101 1，0.108 6 and 0.108 5 h^-1 respectively; Ka at pH of 6.4, 6.9, 7.4 and 7.9 were 0.101 0，0.118 5，0.108 6 and 0.141 7 h^-1 respectively; Ka at the concentration of 0.3%，0.5%，1.0% of Tween-80 were 0.107 8，0.108 6 and 0.102?3 h^-1 respectively CONCLUSION The concentrations of nitrendipine and Tween-80 and the pH of drug solution had no distinctive effect on the absorption kinetics. The absorption of nitrendipine was a first-order process with passive diffusion mechanism. Nitrendipine was well absorbed at all segments of intestine in rats, which indicate that nitrendipine could be prepared as sustained-release dosage form for administration once a day.