A Novel Evaluation Method On Drugs' Absorption In Intestine

Pharmacokinetci parameters in intestinal absorption, such as effective absorptive location, absorptive mechanism, metabolic characteristics, influential factors, are significant important for the type and dosage of oral drugs, design of drug structure, slowrelease-drugs and controlrelease-drugs. In this paper, a novel method are established to test the absorbability of small intestine using microdialysis techniques, drug permeability of small intestine and drug metabolism curve in vivo are got to provide a reference for drug design.Microdialysis techniques are used to investigate the absorbability of small intestine. According to anatomical characteristics of mesenteric vein, ears artery of rabbits and carotid artery of rats, the structure of microdialysis probes is improved, the probe is supple and have a short handle. A guiding needle is used to insert the pipe that guides the microdialysis probe into vessels and this method is more exactly and simply than used methods. The multichannel microdialysis model is developed in the small intestine of rabbits and rats. The probes are implanted in the mesenteric vein, small intestine lumen and artery. Synchronic microdialysis of the three sites begin immediately after dosing of drugs. High Performance Liquid Chromatography is used to test the drug concentration of dialysate, then the absorptive rate of small intestine can be calculated.Gastrodin is took as an example to testify the multichannel model. The concentration versus time curves of mesenteric vein, artery and intestinal lumen can be obtained in both rabbits and rats, then the permeable rate of drugs in the small intestine can be calculated. The results shows that the permeable rate in the small intestine of rabbits is 0.79±0.11‰, while 7.3±2.4‰in rats. All of the above demonstrates that microdialysis is an available technique to investigate absorbability of small intestine, which can be accomplished in situ without damage conditions of small intestine, so real absorbability of small intestine can be got which is valuable for guiding preclinical medication.