Numerical Investigation On The Mass Transfer Process Of Drugs In The Intestine

The diffusion and absorption of drugs in the small intestine is a complex physiological process.Study on the law of drug absorption and mass transfer in the small intestine and its related mechanisms,and obtain information on the absorption kinetics,effective absorption site,absorption mechanism and factors affecting absorption of the drug in the intestine are of great importance for new drug design,formulation improvement,and reducing the risk of investment in new drug research and development.This article elaborates on the anatomical structure and physiological movement characteristics of the human small intestine,and the internal physiological structure and function of the small intestine are analyzed and summarized comprehensively.Based on the related theory of fluid mass transfer,combined with the anatomical structure of the small intestine,physiological movement and related factors affecting drug absorption,a physical model of drug mass transfer in the small intestine was established.Then,the explicit control volume integral method and the mass conservation law are used for detailed numerical simulation analysis,and some conclusions with certain significance are obtained.The effects of physical and chemical properties of drugs such as drug molecular diffusion coefficient,drug reaction consumption rate,drug oil-water partition coefficient,and the intrinsic physiological movement of the small intestine,ie,segmentation contraction and peristalsis motion,on drug mass transfer in human small intestine were discussed.The results show that the absorption of oral drugs has certain requirements on the drug diffusion coefficient,if the diffusion coefficient of the drug itself is too low,the mass transfer in the small intestine and the absorption of the small intestine will be too slow,resulting in the drug being difficult to be absorbed by the body.Too fast a rate will inactivate a large number of drugs and will not be effective by the human body,considering a series of complicated reaction processes that may exist in the intestinal tract,oral preparations should be selected to be more stable and less prone to inactivation,therefore,the first-stage reaction dissipation rate of the drug should be as small as possible as k=1×10^-4s^-1.The increase of the oil-water partition coefficient of the drug can increase the absorption rate of the drug,and the initial increase is obvious,but when the oil-water partition coefficient of the drug reaches after a certain value,increase the oil-water partition coefficient,that is,increase the fat solubility of the drug has no obvious help for the absorption of the drug in the intestine.When the frequency of segmentation contraction of the small intestine is high,the absorption of the drug is obviously promoted,and after the frequency is low to a certain extent,there is almost no promotion of the absorption of the drug in the small intestine;the lower the frequency of peristalsis of the small intestine and the shorter the advancement distance,the longer the residence time of the drug in the small intestine,which is beneficial to the drug being fully absorbed by the human body,however,the segmentation contraction and peristalsis of the human intestine are mutually influential,and the segmentation contraction and peristalsis in the small intestine need to reach a balance in order to achieve the best state of absorption of the drug.Finally,the main contents of this work are summarized,and the future works of drug mass transfer and absorption in the small intestine are prospected.