基于微流控芯片的体外肠道吸收模型构建及其应用进展

肠道是口服药物吸收的主要部位，肠道的上皮细胞上含有绒毛和微绒毛，它们通过增加表面积等因素促进分泌、细胞黏附和吸收。传统的二维/三维（2D/3D）细胞培养模型、动物模型在研究药物吸收方面发挥了重要作用，但是由于缺乏足够的人体药动学的可预测性或伦理问题等，其应用存在一定局限性。因此，以体外活细胞为基础，模拟人肠道的核心结构和关键功能是构建基于微流控芯片的肠道模型的研究重点。该模型是利用微加工技术制备出的模拟人体肠道的复杂微结构、微环境和生理功能的微流控芯片仿生系统。与2D细胞培养和动物实验相比，肠芯片模型能有效地模拟人体内环境，在药物筛选方面更具特异性。本综述概括了国内外肠芯片模型以及与肠道相关的多器官耦合芯片模型的研究进展，及其在疾病建模、药物吸收和转运方面的应用，并总结了当前肠芯片模拟肠道稳态和疾病面临的挑战，为进一步建立更可靠的体外肠芯片模型提供参考。     

Caco-2细胞系及其在药物吸收、代谢中的应用

由于小肠的生理结构适用于药物吸收 ,所以口服给药是最广泛、最方便的给药途径之一 ,因此研究药物在肠道的吸收与代谢就显得十分必要。目前用于药物吸收的实验方法主要有 :在体肠回流法 ,肠襻法 ,分离肠粘膜法、外翻囊法等 [1 ]。由于这些方法存在采用动脉组织及其它一些局限性 ,近年来人们尝试使用人肠细胞培养系统来研究药物在肠道的吸收和代谢 ,以快速筛选口服药物。Caco-2细胞模型被认为是目前最好的体外吸收模型 ,可用于快速评估新药的细胞渗透性、阐明药物转运的途径、评价提高膜通透性的方法、确定被动扩散的药物最合适的理化性质和…     

Cac0-2细胞系及其在药物吸收、代谢中的应用

由于小肠的生理结构适用于药物吸收,所以口服给药是最广泛、最方便的给药途径之一,因此研究药物在肠道的吸收与代谢就显得十分必要.目前用于药物吸收的实验方法主要有:在体肠回流法,肠襻法,分离肠粘膜法、外翻囊法等[1].由于这些方法存在采用动脉组织及其它一些局限性,近年来人们尝试使用人肠细胞培养系统来研究药物在肠道的吸收和代谢,以快速筛选口服药物.Caco-2细胞模型被认为是目前最好的体外吸收模型,可用于快速评估新药的细胞渗透性、阐明药物转运的途径、评价提高膜通透性的方法、确定被动扩散的药物最合适的理化性质和评估新药的潜在毒性作用等,成为药物吸收研究的必备手段.本文就Caco-2细胞及其应用作一简要介绍.     

口服药物中药用辅料对胃肠渗透影响的研究进展

目的： 汇总分析国内外对于药用辅料影响口服药物胃肠渗透的相关研究,及其常用的体外吸收预测模型,为药物制剂的研发、处方的筛选等提供参考。方法：对药用辅料影响药物胃肠渗透的方式进行分类、归纳和整理,同时对几种常用于体外吸收预测的模型进行分析。结果：药用辅料可以通过改变胃肠蠕动、影响肠细胞P-糖蛋白介导的外排和影响药物的溶出,从而影响药物活性成分在胃肠道内的渗透吸收。常用的体外吸收预测模型主要有人结肠腺癌细胞模型、动物在体和离体模型及利用平行人工膜的实验模型。结论：在对口服药物的体内吸收进行研究时,区别于以往辅料作为惰性物质的观念,应更加注重辅料对药物在胃肠吸收过程中的影响。在体内外吸收预测模型方面,平行人工膜通透性测定以其分析快速且重现性好等优点引起了越来越多的关注。     

Caco-2细胞模型在天然药物吸收研究中的应用

目的Caco-2细胞模型为经典的口服药物体外吸收模型。此文介绍了Caco-2细胞模型的来源与特点,综述了Caco-2细胞模型在天然药物吸收研究中的应用现状,并对Caco-2细胞模型在天然药物研究中的应用前景进行了探讨。     

Caco-2细胞模型在口服药物吸收研究中的应用

目的对Caco 2细胞模型在口服药物肠吸收研究中的应用作一综述。方法在引用了自1974~2004年的32篇文献的基础上,通过介绍并比较体外Caco 2模型和体内药物吸收转运的不同途径,讨论Caco 2单层细胞模型在预测不同类药物体内吸收中的作用。结果Caco 2细胞模型可以预测不同转运途径的药物体内吸收,尤其适用于被动转运药物,这一细胞模型在药物吸收机制、处方组成透膜性和黏膜毒性、药物吸收过程中的相互作用、药物的化学结构和体内转运关系、药物吸收限速因素、药物代谢稳定性及pH对药物吸收的影响等研究中均有较广泛的应用。结论Caco2细胞模型用于预测各种途径的药物吸收,在细胞水平上提供了大量与吸收相关的信息,是口服药物高通量筛选的良好工具。     

药物肠道吸收研究方法

药物在肠道内的吸收程度和吸收特征是影响口服药物生物利用度的重要因素。肠道吸收研究可以预测影响药物在肠道吸收的机制与因素,研究方法主要包括体内法（invivo）、在体法（insitu）、体外法（invitro）等。就目前药物小肠吸收的研究方法及其特点进行综述。     

肠道细胞色素P450和P-糖蛋白对口服药物生物利用度的影响

目的综述肠道细胞色素P450和P-糖蛋白(P-gp)对口服药物生物利用度的影响,包括CYP450、Pgp的作用及CYP与Pgp的联合作用。方法收集、阅读并分析近十年来关于肠道细胞CYP450和Pgp影响口服药物生物利用度的文献。结果 CYP450和Pgp在胃肠道均具有高表达,且两者的底物具有显著的重叠性,所以肠道细胞CYP450对已吸收药物的生物转化作用和肠道细胞中Pgp对已吸收药物的主动外排作用是影响口服药物生物利用度的重要因素。结论肠道细胞CYP450和Pgp对药物的口服生物利用度具有重要影响。     

Caco-2细胞模型——药物吸收研究的有效“工具”

吸收过程是决定口服药物生物利用度的重要因素 ,然而很多药物的吸收机制还不明确。Caco 2细胞模型是目前最好的体外吸收模型 ,在药物的吸收过程及吸收机制的研究方面有广泛的应用 ,尤其在中药吸收研究方面 ,Caco 2细胞模型的应用成为目前的热点。另外 ,Caco 2细胞模型在药物代谢方面也有应用。因此 ,Caco 2细胞模型将成为药物吸收研究的重要手段 ,有助于加快新药筛选和开发的速度。     

药物肠吸收的实验研究方法概述

目前,口服给药仍是最常见的临床给药途径。口服药物的主要吸收部位在小肠,肠上皮细胞、肠内酶对药物的代谢及屏障作用、药物对小肠上皮中多种转运系统的特异性等均影响口服药物的生物利用度。因此,研究药物在肠内的吸收机制、代谢特点及其影响因素有助于药物的结构设计、处方筛选、工艺优化以及评估药物的口服吸收效果,是口服药物开发的重要环节。本文着重简要介绍目前较常用的研究药物肠道吸收的实验模型及其特点。     

Application of Method Suitability for Drug Permeability Classification

Experimental models of permeability in animals, excised tissues, cell monolayers, and artificial membranes are important during drug discovery and development as permeability is one of several factors affecting the intestinal absorption of oral drug products. The utility of these models is demonstrated by their ability to predict a drug’s in vivo intestinal absorption. Within the various permeability models, there are differences in the performance of the assays, along with variability in animal species, tissue sources, and cell types, resulting in a variety of experimental permeability values for the same drug among laboratories. This has led to a need for assay standardization within laboratories to ensure applicability in the drug development process. Method suitability provides a generalized approach to standardize and validate a permeability model within a laboratory. First, assay methodology is optimized and validated for its various experimental parameters along with acceptance criteria for the assay. Second, the suitability of the model is demonstrated by a rank order relationship between experimental permeability values and human extent of absorption of known model compounds. Lastly, standard compounds are employed to classify a test drug’s intestinal permeability and ensure assay reproducibility and quality. This review will provide examples of the different aspects method suitability for in situ (intestinal perfusions), ex vivo (everted intestinal sacs, diffusion chambers), and in vitro (cell monolayers, artificial membranes) experimental permeability models. Through assay standardization, reference standards, and acceptance criteria, method suitability assures the dependability of experimental data to predict a drug’s intestinal permeability during discovery, development, and regulatory application.     

Establishment of a triple co-culture in vitro cell models to study intestinal absorption of peptide drugs

In vitro cell culture models for studying oral drug absorption during early stages of drug development have become a useful tool in drug discovery and development, with respect to substance throughput and reproducibility. The aim of this study was to establish an in vitro cellular model based on human colon carcinoma Caco-2, mucus-producing HT29, and Raji B cells in order to design a model that more accurately mimics the small intestinal epithelial layer. Normal oriented model was set up by seeding co-cultures of Caco-2 and HT29 cells into Transwell filters and maintained under identical conditions following addition of Raji B to the basolateral chamber. Inverted model was set up seeding Caco-2 and HT29 cells on the basolateral chamber and then transferred in the Transwell device with the epithelial cells facing the basolateral chamber following Raji B addition to the apical compartment. Morphological differences on size and thickness of cell membranes were detected between the models studied by using fluorescence microscopy. On the triple co-culture models, cell membranes were increasing in size and thickness from the Caco-2 to Caco-2/HT29 and Caco-2/Raji B. Also, the nuclei seem to be larger than in the other studied models. Insulin permeation was higher on the triple co-culture model when compared to the Caco-2/HT29 co-culture model. Also, insulin permeation as mediated by nanoparticles and insulin solution permeation was higher on the normal oriented Caco-2/HT29/Raji B model as compared to the inverted model. Overall, our results suggest that Caco-2/HT29/Raji B triple co-culture normal oriented cellular model may be reliable to obtain a more physiological, functional, and reproducible in vitro model of the intestinal barrier to study protein absorption, both in solution and when delivered by nanocarriers.     

Towards the characterization of an in vitro triple co-culture intestine cell model for permeability studies

Caco-2 based cell models have been the gold standard in vitro method to study intestinal drug permeability, despite the absence of many important features with major influence in the drug absorption mechanism. In the present work, a triple co-culture comprising Caco-2, HT29-MTX and Raji B cells was established to mimic in a closely way the human intestinal epithelium, presenting the main components in the process of drug absorption, namely the absorptive cells that resemble enterocytes, mucus producers cells and cells able to induce M-cell phenotype on Caco-2 cells. All the three cell lines maintained their function when cultured together with each other being, thus, an asset to new orally administrated drugs development. The seeding ratio of 90:10 between Caco-2 and HT29-MTX showed to be the best to achieve physiological proportions after cells maturation and differentiation in culture. The formation of M-cells phenotype from enterocytes was identified for the first time in a co-culture system comprising Caco-2 and HT29-MTX cells through immunocytochemical techniques. Thus, the triple co-culture model presented in the herein work is a good and reliable alternative to the in vitro methods already existents for the study of drugs permeability.     

In vitro and In vivo evaluation of positively charged liposaccharide derivatives as oral absorption enhancers for the delivery of anionic drugs

Oral delivery of hydrophilic, ionisable drugs remains a major challenge in drug development and a number of active pharmaceuticals fail to reach the market of oral drugs because of a lack of absorption and/or stability issues. One possible approach to improving the bioavailability of such drug candidates is to increase their lipophilicity, which is a key parameter in the permeation across cell membranes. However, modifying the chemical structure by adding lipid residues often results in changes in activity. With ionised molecules, ion‐pairing can be considered to associate charged lipid moieties with the parent drug without altering its structure and therefore activity. This study presents the results of in vitro and in vivo evaluation of a series of synthetic, positively charged liposaccharide derivatives combined with an anionic model drug, piperacillin. The antimicrobial activity, plasma stability, Caco‐2 cell permeability and oral absorption of the conjugates were assessed. Increases in apparent permeability were observed in vitro for three of the tested formulations, while retaining the antibacterial activity of the drug. However, the in vivo intestinal absorption of piperacillin formulated with the liposaccharide derivatives was found unchanged, possibly due to molecular dissociation, early degradation or structural differences between the intestinal epithelium and cultured monolayers. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2333–2342, 2010     

Fruit juice inhibition of uptake transport: a new type of food-drug interaction

A new type of interaction in which fruit juices diminish oral drug bioavailability through inhibition of uptake transport is the focus of this review. The discovery was based on an opposite to anticipated finding when assessing the possibility of grapefruit juice increasing oral fexofenadine bioavailability in humans through inhibition of intestinal MDR1-mediated efflux transport. In follow-up investigations, grapefruit or orange juice at low concentrations potentially and selectively inhibited in vitro OATP1A2-mediated uptake compared with MDR1-caused efflux substrate transport. These juices at high volume dramatically depressed oral fexofenadine bioavailability. Grapefruit was the representative juice to characterize the interaction subsequently. A volume–effect relationship study using a normal juice amount halved average fexofenadine absorption. Individual variability and reproducibility data indicated the clinical interaction involved direct inhibition of intestinal OATP1A2. Naringin was a major causal component suggesting that other flavonoids in fruits and vegetables might also produce the effect. Duration of juice clinical inhibition of fexofenadine absorption lasted more than 2 h but less than 4 h indicating the interaction was avoidable with appropriate interval of time between juice and drug consumption. Grapefruit juice lowered the oral bioavailability of several medications transported by OATP1A2 (acebutolol, celiprolol, fexofenadine, talinolol, L-thyroxine) while orange juice did the same for others (atenolol, celiprolol, ciprofloxacin, fexofenadine). Juice clinical inhibition of OATP2B1 was unresolved while that of OATP1B1 seemed unlikely. The interaction between grapefruit juice and etoposide also seemed relevant. Knowledge of both affected uptake transporter and drug hydrophilicity assisted prediction of the clinical interaction with grapefruit or orange juice.     

Current methodologies used for evaluation of intestinal permeability and absorption

This review article will focus on the various techniques that are currently employed by drug discovery scientists in evaluating permeability/absorption of drug candidates during the drug candidate selection process. Various preclinical methodologies are available; each having advantages and disadvantages, but it is the judicious use of these techniques that can help identify drug candidates that will be well absorbed in humans. It is well recognized that the human intestinal permeability cannot be accurately predicted based on a single methodology (in vitro: tissue/cell culture, in situ, or in vivo).     

Enhancing Intestinal Absorption of a Model Macromolecule via the Paracellular Pathway using E-Cadherin Peptides

Membrane permeation enhancers have received significant attention in recent years for enabling the oral absorption of poorly permeable drug molecules. In this study, we investigated the ability of His-Ala-Val (HAV) and Ala-Asp-Thr (ADT) peptides derived from the extracellular-1 (EC1) domain of E-cadherin proteins to increase the paracellular permeation and intestinal bioavailability of the poorly permeable model macromolecule, fluorescein-isothiocyanate dextran with average molecular weight 4000 (FD4). The in vitro enzymatic stability of linear and cyclic E-cadherin peptides was characterized under simulated gastric and intestinal conditions, and the cyclic E-cadherin peptides, HAVN1 and ADTC5, which demonstrated excellent stability in vitro, were advanced to in vivo intestinal instillation studies and compared against the established surfactant membrane permeation enhancer, sodium caprate (C₁₀). Cyclic HAVN1 and ADTC5 peptides increased FD4 bioavailability by 7.2- and 4.4-fold compared to control, respectively (not statistically significant). In contrast, C₁₀ provided a statistically significant 10.7-fold relative bioavailability enhancement for FD4. Importantly, this study represents the first report of cyclic E-cadherin peptides as intestinal membrane permeation enhancers. The findings described herein demonstrate the potential of enzymatically stabilized cyclic E-cadherin peptides for increasing poorly permeable drug absorption via the oral route.     

Caco-2细胞模型在药物体外研究中的应用

Caco-2细胞模型是一种筛选药物离体口服特性的模型,已广泛用于评价药物在小肠的吸收特性和各种转运机制的研究.现综述Caco-2细胞单层模型的基本特点及其在药物的小肠吸收、代谢以及高通量筛选等方面的应用.