转运体介导的食物-药物相互作用

食物与药物之间的相互作用普遍存在,且作用机制也多种多样。目前,研究较多的是单个食物或食物中的某些营养成分通过调节药物转运体或代谢酶的功能从而影响药物的体内过程。食物对药物体内过程的影响包括吸收、分布、代谢、排泄四个方面,并且主要是调节其中参与的药物转运体和代谢酶的功能。转运体介导的食物对药物体内吸收的影响主要是通过调节肠上皮摄取型和外排型的转运体,从而影响药物的吸收;对分布的影响主要是通过调节体内一些屏障中的转运体;对代谢的影响主要是同时调节药物代谢酶和转运体;对排泄的影响是通过调节肾脏和肝脏胆汁排泄的药物转运体,从而影响药物的清除率。因此,转运体介导的食物与药物相互作用直接影响药物治疗的效果。     

转运体在药物肾脏排泄中的重要作用

转运体是细胞膜上的功能性蛋白,在肾脏中表达广泛,对许多内源性或外源性物质的肾脏分泌及重吸收起到了至关重要的作用。许多药物（包括有机阴离子药物、有机阳离子药物及肽类药物等）在肾脏排泄的过程中,经主要集中在近端肾小管的转运体主动转运介导。临床合用某些药物时可能在肾脏发生转运体介导的相互作用。从肾脏主要转运体的分布及功能出发,综述其在药物肾脏排泄中的作用。     

动物生理节律影响药物代谢过程的分子基础及其调节机制的研究进展

实验动物在药物研究与开发领域中发挥着不可替代的作用。药物在体内吸收、分布、代谢及排泄(ADME)过程是其药效或毒性作用产生的前提。国内外研究表明,机体参与药物体内过程各个环节的生理功能状态具有不同程度的时间节律性。肠道转运体、肝脏药物代谢酶及肾脏在药物ADME过程中发挥着重要作用。本文综述了肠道药物转运体、肝脏药物代谢酶及肾脏排泄等环节的生理节律性现象及其分子基础和调节机制。     

常见肠、肝、肾疾病以及糖尿病状态下相关药物转运体的变化及其应用意义

转运体是位于细胞膜上的功能性膜蛋白。目前研究证明转运体在药物的吸收、分布以及排泄过程中发挥着重要的作用,其中以肠道、肝脏以及肾脏转运体的作用最为明显。疾病状态下转运体的表达和功能会发生改变,影响药物在体内的处置过程,使药物的药代动力学发生明显改变而对疾病的药物治疗产生影响。本文综述了常见肠道疾病、肝脏疾病、肾脏疾病以及糖尿病状态下相关转运体的变化及其对临床药物治疗的影响。     

药物转运体与中枢神经药理

细胞膜上有三类主要的功能蛋白，即膜受体、离子通道与转运体。转运体是细胞内外物质转运的分子基础，包括离子转运体、神经递质转运体、营养物质（如氨基酸、葡萄糖等）转运体以及外来物质转运体。药物转运体（drug transporter）本质上属于外来物质（xenobiotic）转运体，是机体内物质转运系统的组成部分。药物转运体在药物吸收、分布、代谢、排泄等体内过程中起非常重要的作用，是影响药物效应以及产生药物相互作用的重要因素。近年来，对药物转运体的了解逐步深入，成为药理学研究中不可忽视的一个组成部分。     

肠道药物转运体及其研究方法

口服药物在肠道中的吸收是决定药物生物利用度的重要因素。肠道中有许多药物膜转运蛋白介导药物的吸收、分布、排泄及药物相互作用等。明确其转运机制有利于提高药物的安全性和有效性,从而指导临床合理用药。通过体内外方法预测药物经转运体在肠道中的转运情况。本文介绍了肠道内转运药物的主要膜转运蛋白,阐述了口服药物经肠道转运机制,概括了研究肠道药物转运体的主要研究方法,并对多种体内外转运体研究方法的优缺点进行了比较。     

代谢酶和转运体介导的中药-西药相互作用的药动学机制研究进展

随着中草药的广泛应用,中药-西药相互作用(herb-drug interaction,HDI)问题日益凸显。代谢酶和转运体是影响药物体内处置过程的重要因素,其表达和功能的改变常常引起药代动力学的变化,是药物相互作用的主要靶点。代谢酶负责药物的代谢清除,主要包括细胞色素P450超家族(CYP)、UDP-葡萄糖醛酸基转移酶(UGT)以及磺酸化酶(SULT);转运体参与药物的口服吸收、体内分布以及排泄,主要包括肠道转运体、肾脏转运体、肝脏转运体以及脑转运体等。葛根、银杏叶、人参、圣约翰草等中草药在临床上应用广泛,且常与西药联合应用,其成分与代谢酶以及转运体存在相互作用,容易产生HDI。本文综述代谢酶、转运体介导的HDI的药代动力学机制,阐述常用中草药在与西药联合应用时应注意的问题。     

转运体在药物经肝脏清除过程中的作用

肝脏在药物的体内清除过程中具有重要作用,它不仅是药物代谢的主要场所,还控制着药物及其代谢物的胆汁排泄过程。转运体是控制细胞内外物质传输的一类功能性膜蛋白,其在肝脏有广泛表达,并能对药物进入肝细胞以及排泄至胆汁的过程进行调控,因而,对于肝脏清除过程具有重要作用。本文从肝脏中重要转运体的分布、功能以及底物选择性出发,对其在药物的肝脏清除中的作用、由其引起的药物药物相互作用以及重要转运体的基因多态性研究进行了综述。     

肾脏转运体和/或代谢酶介导药物排泄及药物相互作用的研究进展

肾脏是人体最重要的排泄器官。肾单元近端小管细胞具有多种药物转运体和代谢酶,在药物及其代谢物处置中发挥关键作用。近端小管细胞中主要转运体包括有机阴离子转运体、有机阳离子转运体、有机阳离子/肉毒碱转运体、多药及毒素外排转运蛋白、P-糖蛋白、乳腺癌耐药蛋白和多药耐药相关蛋白;主要代谢酶包括细胞色素P450酶,UDP-葡萄糖醛酸基转移酶、磺酸基转移酶、谷胱甘肽S-转移酶。肾脏转运体和/或代谢酶介导药物相互作用(DDIs)是临床关注的重要问题。肾脏转运体和代谢酶存在密切协作关系,在肾脏也存在多种相互作用现象(包括转运-转运相互作用,代谢-代谢相互作用和转运-代谢相互作用),其显著影响药物肾脏处置、临床疗效和肾毒性。本文系统阐述了这些相互作用对药物及其代谢物的肾脏排泄、药动学、DDIs和肾毒性的影响。今后需要进一步阐明肾脏转运-代谢相互作用机制,将有助于研究体内药物肾脏处置和DDIs,促进临床合理用药。     

肾脏转运体介导抗病毒药物肾排泄的研究进展

目的:了解肾脏转运体介导抗病毒药物肾排泄的研究现状,为临床合理用药提供参考.方法:对近年抗病毒药物与肾脏转运体相关的文献进行综述.结果:有机阴离子转运体(Organic Anion Transporters,OAT1～3)和有机阳离子转运体(Organic Cation Transporters,OCT1～3)介导药物流入细胞内,而ATP结合转运体(ATP Binding Cassette,P-gp,MRP2～5)介导药物从细胞排出.寡肽转运体(Peptide Transporters,PEPT1～2)介导伐昔洛韦双向扩散.结论:通过介导药物的摄取和排出,肾脏转运体在调节体内常用抗病毒药物浓度时发挥重要的作用.     

The isolated perfused rat kidney model: a useful tool for drug discovery and development

Over the past three decades, the Isolated Perfused Rat Kidney (IPK) has been used to study numerous aspects of renal drug disposition. Among the available ex-vivo methods to study renal transport, the IPK allows for elucidation of the overall contributions of renal transport mechanisms on drug excretion. Therefore, IPK studies can provide a bridge between in vitro findings and in vivo disposition. This review paper begins with a detailed overview of IPK methodology (system components, surgical procedure, study design). Various applications of the IPK are then presented. These applications include characterizing renal excretion mechanisms, screening for clinically significant drug interactions, studying renal drug metabolism, and correlating renal drug disposition with drug-induced changes in kidney function. Lastly, the role of IPK studies in drug development is discussed. Demonstrated correlations between IPK data and clinical outcomes make the IPK model a potentially useful tool for drug discovery and evaluation.     

Renal Transport of Drugs: An Overview of Methodology with Application to Cimetidine

The development of new methods to study transport processes in renal epithelia has greatly enhanced our knowledge of the mechanisms involved in the transport of a number of endogenous compounds. More recently, these methods have been applied to study mechanisms of specific drug transport. This article is intended to provide an overview of the various methods used to study renal elimination of compounds. References to more detailed reviews of the individual methods are provided. Studies of the renal transport of cimetidine, a histamine H₂-receptor antagonist, are presented to illustrate the application of these methods to the study of specific drugs. Methods such as clearance techniques and the Sperber chicken preparation used to study renal elimination of compounds in whole animals are briefly described. Techniques to identify the site of renal transport including stop flow, isolated perfused tubules, and micropuncture methods are discussed and references to more technical reviews are cited. The more recently developed methods of isolated membrane vesicles for studying transport across the individual polar membranes of the proximal tubule are discussed along with the relevant studies of the use of these membranes in elucidating the mechanisms involved in the renal transport of cimetidine. Finally, the use of cultured renal epithelial cell lines in studying renal transport is described. Knowledge of drug transport mechanisms in the kidney is important both in drug targeting to the kidney and in understanding the pharmacokinetics of renally eliminated drugs. As exemplified by the studies with cimetidine, only by combining the data from experiments using diverse methodology can the mechanisms involved in the renal excretion of compounds be delineated. With the use of existing methods and the development of new technologies, many of the questions related to drug transport mechanisms can be addressed.     

Mechanisms and clinical implications of renal drug excretion.

The body defends itself against potentially harmful compounds like drugs, toxic compounds, and their metabolites by elimination, in which the kidney plays an important role. Renal clearance is used to determine renal elimination mechanisms of a drug, which is the result of glomerular filtration, active tubular secretion and reabsorption. The renal proximal tubule is the primary site of carrier-mediated transport from blood to urine. Renal secretory mechanisms exists for, anionic compounds and organic cations. Both systems comprises several transport proteins, and knowledge of the molecular identity of these transporters and their substrate specificity has increased considerably in the past decade. Due to overlapping specificities of the transport proteins, drug interactions at the level of tubular secretion is an event that may occur in clinical situation. This review describes the different processes that determine renal drug handling, the techniques that have been developed to attain more insight in the various aspects of drug excretion, the functional characteristics of the individual transport proteins, and finally the implications of drug interactions in a clinical perspective.     

Transporters as a determinant of drug clearance and tissue distribution

Transporters play an important role in the processes of drug absorption, distribution and excretion. In this review, we have focused on the involvement of transporters in drug excretion in the liver and kidney. The rate of transporter-mediated uptake and efflux determines the rate of renal and hepatobiliary elimination. Transporters are thus important as a determinant of the clearance in the body. Even when drugs ultimately undergo metabolism, their elimination rate is sometimes determined by the uptake rate mediated by transporters. Transporters regulate the pharmacological and/or toxicological effect of drugs because they limit their distribution to tissues responsible for their effect and/or toxicity. For example, the liver-specific distribution of some statins via organic anion transporters helps them to produce their high pharmacological effect. On the other hand, as in the case of metformin taken up by organic cation transporter 1, drug distribution to the tissue(s) may enhance its toxicity. As transporter-mediated uptake is a determinant of the drug elimination rate, drug–drug interactions involving the process of transporter-mediated uptake can occur. In this review, we have introduced some examples and described their mechanisms.

More recently, some methods to analyze such transporter-mediated transport have been reported. The estimation of the contributions of transporters to the net clearance of a drug makes it possible to predict the net clearance from data involving drug transport in transporter-expressing cells. Double transfected cells, where both uptake and efflux transporters are expressed on the same polarized cells, are also helpful for the analysis of the rate of transporter-mediated transcellular transport.     

寡肽转运体PEPT2在药物肾脏转运中的作用和活性调节

目的：研究肽转运体在药物肾脏转运中的作用和活性调节.方法：通过文献检索和分析,对肽转运体PEPT2的转运作用和活性调节进行探讨.结果：肾小管上分布的药物转运体参与了多种药物在肾脏的重吸收和分泌过程,PEPT2的活性在糖尿病或者慢性肾衰等疾病的情况下会上调.结论：随着PEPT2的结构、分布、转运作用和对其作用发挥的影响因素的进一步研究,对于它们在多肽类药物肾脏排泄中的作用有了更为深刻的了解,使其成为新药开发中重要的药物转运体.     

Expression Levels of Renal Organic Anion Transporters (OATs) and Their Correlation with Anionic Drug Excretion in Patients with Renal Diseases

PURPOSE: Because the urinary excretion of drugs is often decreased in renal diseases, dosage regimens are adjusted to avoid adverse drug reactions. The aim of present study was to clarify the alteration in the levels of renal drug transporters and their correlation with the urinary drug excretion in renal diseases patients. METHODS: We quantified the mRNA levels of human organic anion transporters (hOATs) by real-time polymerase chain reaction and examined the excretion of the anionic drug, cefazolin, in renal disease patients. Moreover, transport of cefazolin by hOAT1 and hOAT3 were examined using HEK293 transfectants. RESULTS: Among four hOATs, the level of hOAT1 mRNA was significantly lower in the kidney of patients with renal diseases than in the normal controls. The elimination constant of cefazolin showed a significant correlation with the values of phenolsulfonphthalein test and mRNA levels of hOAT3. The uptake study using HEK293 transfectants revealed that cefazolin and phenolsulfonphthalein were transported by hOAT3. CONCLUSIONS: These results suggest that hOAT3 plays an important role for anionic drug secretion in patients with renal diseases and that the expression levels of drug transporters may be related to the alteration of renal drug secretion.     

The genetic polymorphism of drug transporters: functional analysis approaches

Evidence is accumulating to strongly suggest that drug transporters are one of the determining factors governing the pharmacokinetic profile of drugs. To date, a variety of drug transporters have been cloned and classified as solute carriers and ATP-binding cassette transporters. Such drug transporters are expressed in various tissues such as the intestine, brain, liver, and kidney, and play critical roles in the absorption, distribution and excretion of drugs. However, at the present time, information is limited regarding the genetic polymorphism of drug transporters and its impact on their function. In this context, we have undertaken the functional analyses of the polymorphisms identified in drug transporter genes. This article aims to provide an overview on the functional aspects of the non-synonymous polymorphisms of drug transporters and to present standard methods for the evaluation of the effect of polymorphisms on their function.     

转运蛋白在药物肾脏转运中的重要作用

肾脏转运蛋白对药物在体内排泄和重吸收过程重要作用.本文对肾脏转运蛋白的种类、分布、作用机制及其对药物排泄过程的影响和可能产生的药物相互作用做了综述.