转运体介导中药与化学药相互作用研究进展

ATP结合盒转运体家族和溶质转运体家族的转运体参与众多的中药与化学药相互作用过程,因其可介导内外源性药物及其代谢物的跨膜转运。转运体同细胞色素P450酶类似,会对特征底物的血药浓度和组织分布产生一定影响,从而改变药物的药效或者毒副作用。本文综述了具有重要临床意义的P-糖蛋白、乳腺癌耐药蛋白、有机阴离子转运体、有机阳离子转运体和有机阴离子转运多肽等5种转运体所介导的中药与化学药相互作用,以期为临床联合用药提供一定的理论依据。     

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。     

药物转运体OAT2研究进展

有机阴离子转运体2(OAT2)属于有机阴离子转运体家族成员,主要分布于肝肾,介导肌酐、尿酸等内源性物质及多种外源性药物的跨膜转运。OAT2对外源性物质如药物的体内过程如吸收、分布、代谢和排泄过程起着重要作用。研究表明OAT2的表达与活性被药物、疾病、性别及基因多态性等多种因素影响,亦受到核受体等信号通路调控。故本文综述药物转运体OAT2的结构与分布、底物、调控机制、临床意义的研究进展,为OAT2可能介导药物相互作用及药物疗效预测提供参考。     

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。     

转运体介导的核苷类抗病毒药与其他药物联合应用的相互作用研究

有机阳离子转运体、有机阴离子转运体、P糖蛋白、多药耐药蛋白和核苷转运体是机体内参与核苷类抗病毒药转运及消除的蛋白,转运体通过介导药物的摄取和排出,能够调节体内抗病毒药的浓度,从而影响药物在体内的药动学和药效学行为。本文通过对核苷类抗病毒药和机体转运体相关文献进行综述,探究转运体介导的核苷类抗病毒药与其他药物联合应用时的相互作用,为临床合理用药提供参考。     

肠道ABC转运体的结构、功能及其调节的研究进展

肠道转运体由于在控制药物吸收、分布和代谢等药物动力学过程中起重要作用,目前已引起研究者的高度重视。根据底物跨膜转运方向转运体分为内转运体和外转运体两类。其中,内转运体主要介导氨基酸、核酸等营养物质的转运;而外转运体主要介导药物排泌,它们主要表达于肠道上皮细胞的顶膜上,能转运阴离子、氨基酸、多肽、糖类分子、维生     

疾病状态下有机阴离子转运体表达和功能的变化及其机制研究进展

有机阴离子转运体属于溶质转运体22亚家族成员，是一类重要的摄取类转运体，其有多个亚型。有机阴离子转运体在体内介导多种小分子内源性物质的转运，起到维持机体内环境稳态的作用。此外，临床上许多药物也是有机阴离子转运体的底物。研究表明某些疾病可能导致有机阴离子转运体表达和功能的异常改变，进而影响药物的疗效或导致机体内源性物质水平紊乱。对有机阴离子转运体的分布和功能进行简要介绍，并综述了疾病状态下有机阴离子转运体表达和功能变化及其机制的研究进展。     

血脑屏障的膜蛋白对药物转运及临床治疗的影响

P-糖蛋白,乳腺癌耐药蛋白,多药耐药相关蛋白,有机阴离子转运多肽,有机阴离子转运体,有机阳离子转运体,单羧酸转运体是血脑屏障上常见的膜蛋白,它们与药物的中枢转运密切相关。本文对上述蛋白的底物、转运特点及对临床治疗的影响做了系统的回顾,为药物的优化使用提供参考。     

植物药-化学药间基于有机阴离子转运多肽介导的相互作用研究进展

有机阴离子转运多肽(OATPs)是人及动物体内最重要的细胞膜吸收转运蛋白,在肝脏中有大量分布,介导多种内源性物质及临床常用药物的吸收转运,影响着药物在体内的吸收、分布和清除过程.许多植物药及其有效成分是OATPs的底物,它们对OATPs活性表现出抑制或者诱导作用,从而对OATPs介导的其他药物转运产生影响,改变药物生物利用度或产生不良反应.本文概述了基于OATPs介导的植物药-化学药物之间可能发生的相互作用研究进展.     

有机阴离子转运多肽1B3的研究进展

有机阴离子转运多肽1B3(organic anion transporting polypeptide 1B3,OATP1B3)属于溶质转运体(solute carrier,SLC)超家族,主要负责将内、外源物质转运至肝细胞代谢。OATP1B3是肝脏特异性转运体,通常局限性地分布于肝细胞窦状隙侧肝细胞膜上,近期研究发现在前列腺癌、结肠癌、肺癌等肿瘤组织和细胞中也存在着高表达。溶质转运体1B3(SLCO1B3)具有明显的基因多态性,334T>G和699G>A单体型可明显影响OATP1B3的转运活性,从而介导药物-药物相互作用的发生,导致临床用药的个体差异。此外,OATP1B3可通过作用于孕烷X受体(pregnane X receptor,PXR)和组成性雄甾烷受体(constitutive androstane receptor,CAR)等核受体配体的转运,影响体内PXR和CAR的转录活性,从而调控药物代谢酶如细胞色素P450 3A4(CYP3A4)的表达。本文将对OATP1B3近年来的研究进展进行综述。     

Genetics or environment in drug transport: the case of organic anion transporting polypeptides and adverse drug reactions

INTRODUCTION: Organic anion transporting polypeptide (OATP) uptake transporters are important for the disposition of many drugs and perturbed OATP activity can contribute to adverse drug reactions (ADRs). It is well documented that both genetic and environmental factors can alter OATP expression and activity. Genetic factors include single nucleotide polymorphisms (SNPs) that change OATP activity and epigenetic regulation that modify OATP expression levels. SNPs in OATPs contribute to ADRs. Environmental factors include the pharmacological context of drug-drug interactions and the physiological context of liver diseases. Liver diseases such as non-alcoholic fatty liver disease, cholestasis and hepatocellular carcinoma change the expression of multiple OATP isoforms. The role of liver diseases in the occurrence of ADRs is unknown. AREAS COVERED: This article covers the roles OATPs play in ADRs when considered in the context of genetic or environmental factors. The reader will gain a greater appreciation for the current evidence regarding the salience and importance of each factor in OATP-mediated ADRs. EXPERT OPINION: A SNP in a single OATP transporter can cause changes in drug pharmacokinetics and contribute to ADRs but, because of overlap in substrate specificities, there is potential for compensatory transport by other OATP isoforms. By contrast, the expression of multiple OATP isoforms is decreased in liver diseases, reducing compensatory transport and thereby increasing the probability of ADRs. To date, most research has focused on the genetic factors in OATP-mediated ADRs while the impact of environmental factors has largely been ignored.     

Transporter-mediated drug-drug interactions

Drug-drug interactions are a serious clinical issue. An important mechanism underlying drug-drug interactions is induction or inhibition of drug transporters that mediate the cellular uptake and efflux of xenobiotics. Especially drug transporters of the small intestine, liver and kidney are major determinants of the pharmacokinetic profile of drugs. Transporter-mediated drug-drug interactions in these three organs can considerably influence the pharmacokinetics and clinical effects of drugs. In this article, we focus on probe drugs lacking significant metabolism to highlight mechanisms of interactions of selected intestinal, hepatic and renal drug transporters (e.g., organic anion transporting polypeptide [OATP] 1A2, OATP2B1, OATP1B1, OATP1B3, P-gp, organic anion transporter [OAT] 1, OAT3, breast cancer resistance protein [BCRP], organic cation transporter [OCT] 2 and multidrug and toxin extrusion protein [MATE] 1). Genotype-dependent drug-drug interactions are also discussed.     

Current understanding of hepatic and intestinal OATP-mediated drug-drug interactions

At present, many patients are medicated with various drugs, which are, at the same time, associated with an increased risk of drug-drug interactions (DDIs). Detailed analysis of mechanisms underlying DDIs is the basis of a better prediction of adverse drug events caused by drug interactions. In the last few decades, an involvement of transporters in such processes has been more and more recognized. Indeed, uptake transporters belonging to the organic anion-transporting polypeptide (OATP) family have been shown to interact with a variety of drugs in clinical use. Particularly, the subfamily of OATP1B transporters has been extensively studied, identifying several clinical significant DDIs based on those hepatic uptake transporters. By contrast, the role of OATP2B1 in this context is rather underestimated. Therefore, in addition to known interactions based on OATP1B transporters, we have focused on DDIs probably based on OATP2B1 inhibition in the liver and those possibly owing to the inhibition of OATP2B1-mediated drug absorption in the intestine.     

Uptake transporters of the human OATP family: molecular characteristics, substrates, their role in drug-drug interactions, and functional consequences of polymorphisms

Organic anion transporting polypeptides (OATPs, gene family: SLC21/SLCO) mediate the uptake of a broad range of substrates including several widely prescribed drugs into cells. Drug substrates for members of the human OATP family include HMG-CoA-reductase inhibitors (statins), antibiotics, anticancer agents, and cardiac glycosides. OATPs are expressed in a variety of different tissues including brain, intestine, liver, and kidney, suggesting that these uptake transporters are important for drug absorption, distribution, and excretion. Because of their wide tissue distribution and broad substrate spectrum, altered transport kinetics, for example, due to drug-drug interactions or due to the functional consequences of genetic variations (polymorphisms), can contribute to the interindividual variability of drug effects. Therefore, the molecular characteristics of human OATP family members, the role of human OATPs in drug-drug interactions, and the in vitro analysis of the functional consequences of genetic variations in SLCO genes encoding OATP proteins are the focus of this chapter.     

In vitro evaluation of hepatic transporter-mediated clinical drug-drug interactions: hepatocyte model optimization and retrospective investigation

To assess the feasibility of using sandwich-cultured human hepatocytes (SCHHs) as a model to characterize transport kinetics for in vivo pharmacokinetic prediction, the expression of organic anion-transporting polypeptide (OATP) proteins in SCHHs, along with biliary efflux transporters, was confirmed quantitatively by liquid chromatography-tandem mass spectrometry. Rifamycin SV (Rif SV), which was shown to completely block the function of OATP transporters, was selected as an inhibitor to assess the initial rates of active uptake. The optimized SCHH model was applied in a retrospective investigation of compounds with known clinically significant OATP-mediated uptake and was applied further to explore drug-drug interactions (DDIs). Greater than 50% inhibition of active uptake by Rif SV was found to be associated with clinically significant OATP-mediated DDIs. We propose that the in vitro active uptake value therefore could serve as a cutoff for class 3 and 4 compounds of the Biopharmaceutics Drug Disposition Classification System, which could be integrated into the International Transporter Consortium decision tree recommendations to trigger clinical evaluations for potential DDI risks. Furthermore, the kinetics of in vitro hepatobiliary transport obtained from SCHHs, along with protein expression scaling factors, offer an opportunity to predict complex in vivo processes using mathematical models, such as physiologically based pharmacokinetics models.     

The evolution of the OATP hepatic uptake transport protein family in DMPK sciences: from obscure liver transporters to key determinants of hepatobiliary clearance

Over the last two decades the impact on drug pharmacokinetics of the organic anion transporting polypeptides (OATPs: OATP-1B1, 1B3 and 2B1), expressed on the sinusoidal membrane of the hepatocyte, has been increasingly recognized. OATP-mediated uptake into the hepatocyte coupled with subsequent excretion into bile via efflux proteins, such as MRP2, is often referred to as hepatobiliary excretion. OATP transporter proteins can impact some drugs in several ways including pharmacokinetic variability, pharmacodynamic response and drug-drug interactions (DDIs). The impact of transporter mediated hepatic clearance is illustrated with case examples, from the literature and also from the Pfizer portfolio. The currently available in vitro techniques to study the hepatic transporter proteins involved in the hepatobiliary clearance of drugs are reviewed herein along with recent advances in using these in vitro data to predict the human clearance of compounds recognized by hepatic uptake transporters.     

The role of P-glycoprotein and organic anion-transporting polypeptides in drug interactions.

The use of polytherapy in clinical practice necessitates an appreciation and understanding of the potential for drug interactions. Recent publications provide insight into the role of the active transport systems P-glycoprotein (P-gp) and human organic anion-transporting polypeptides (OATPs) in drug interactions. Active drug transporters influence the bioavailability of a number of drugs by controlling their movement into, and out of, cells. The active transport systems P-gp and OATP play an important role in drug elimination. The activity of these transport systems is controlled, in part, by genetic factors; however, drugs and foods also influence the activity of these systems. It appears that interference with P-gp or OATP, either as upregulation or inhibition, may affect plasma drug concentrations by altering intestinal absorption, proximal renal-tubular excretion or biliary excretion. Overall, the net bioavailability of a drug or substance is affected by the relative contributions of cellular efflux (P-gp) and influx (OATP) mechanisms and to what extent these systems are active during phases of uptake and absorption versus removal and excretion from the body. Many of the drugs and foods that affect active drug transport activity are known to interact with the cytochrome P450 enzyme system; therefore, the net effect of concomitant drug administration is complex. One must now consider the impact of metabolism (CYP-mediated drug biotransformation), P-gp-mediated drug efflux and OATP-mediated uptake when making assessments of drug absorption and distribution.     

Interaction of the antiviral drug telaprevir with renal and hepatic drug transporters

Telaprevir is a new, direct-acting antiviral drug that has been approved for the treatment of chronic hepatitis C viral infection. First data on drug-drug interactions with co-medications such as cyclosporine, tacrolimus and atorvastatin have been reported recently. Drug transporting proteins have been shown to play an important role in clinically observed drug-drug interactions. The aim of this study was therefore to systematically investigate the potential of telaprevir to inhibit drug transporting proteins. The effect of telaprevir on substrate uptake mediated by drug transporters located in human kidney and liver was investigated on a functional level in HEK293 cell lines that over-express single transporter. Telaprevir was shown to exhibit significant inhibition of the human renal drug transporters OCT2 and MATE1 with IC(50) values of 6.4μM and 23.0μM, respectively, whereas no inhibitory effect on OAT1 and OAT3 mediated transport by telaprevir was demonstrated. Liver drug transporters were inhibited with an IC(50) of 2.2μM for OATP1B1, 6.8μM for OATP1B3 and 20.7μM for OCT1. Our data show that telaprevir exhibited significant potential to inhibit human drug transporters. In view of the inhibitory potential of telaprevir, clinical co-administration of telaprevir together with drugs that are substrates of renal or hepatic transporters should be carefully monitored.     

The influence of macrolide antibiotics on the uptake of organic anions and drugs mediated by OATP1B1 and OATP1B3.

Macrolides may cause severe drug interactions due to the inhibition of metabolizing enzymes. Transporter-mediated uptake of drugs into cells [e.g., by members of the human organic anion transporting polypeptide (OATP) family] is a determinant of drug disposition and a prerequisite for subsequent metabolism. However whether macrolides are also inhibitors of uptake transporters, thereby providing an additional mechanism of drug interactions, has not been systematically studied. The human OATP family members OATP1B1 and OATP1B3 mediate the uptake of endogenous substances and drugs such as antibiotics and HMG-CoA reductase inhibitors (statins) into hepatocytes. In this study we investigated the potential role of these uptake transporters on macrolide-induced drug interactions. By using sulfobromophthalein (BSP) and the HMG-CoA reductase inhibitor pravastatin as substrates, the effects of the macrolides azithromycin, clarithromycin, erythromycin, and roxithromycin and of the ketolide telithromycin on the OATP1B1- and OATP1B3-mediated uptake were analyzed. These experiments demonstrated that the OATP1B1- and OATP1B3-mediated uptake of BSP and pravastatin can be inhibited by increasing concentrations of all macrolides except azithromycin. The IC50 values for the inhibition of OATP1B3-mediated BSP uptake were 11 microM for telithromycin, 32 microM for clarithromycin, 34 microM for erythromycin, and 37 microM for roxithromycin. These IC50 values were lower than the IC50 values for inhibition of OATP1B1-mediated BSP uptake (96-217 microM). These macrolides also inhibited in a concentration-dependent manner the OATP1B1- and OATP1B3-mediated uptake of pravastatin. In summary, these results indicate that alterations of uptake transporter function by certain macrolides/ketolides have to be considered as a potential additional mechanism underlying drug-drug interactions.     

Evaluation of drug-transporter interactions using in vitro and in vivo models

Drug transporters, including efflux transporters (the ATP binding cassette (ABC) proteins) and uptake transporters (the solute carrier proteins (SLC)), have an important impact on drug disposition, efficacy, drug-drug interactions and toxicity. Identification of the interactions of chemical scaffolds with transporters at the early stages of drug development can assist in the optimization and selection of new drug candidates. In this review, we discuss current in vitro and in vivo models used to investigate the interactions between drugs and transporters such as P-gp, MRP, BCRP, BSEP, OAT, OATP, OCT, NTCP, PEPT1/2 and NT. In vitro models including cell-based, cell-free, and yeast systems as well as in vivo models such as genetic knockout, gene deficient and chemical knockout animals are discussed and compared. The applications, throughput, advantages and limitations of each model are also addressed in this review.