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.
Key words
nitrendipine /
absorption rate constant /
intestme
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References
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