{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,14]],"date-time":"2026-03-14T14:33:09Z","timestamp":1773498789973,"version":"3.50.1"},"reference-count":54,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2021,9,26]],"date-time":"2021-09-26T00:00:00Z","timestamp":1632614400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/00070\/2020"],"award-info":[{"award-number":["UIDB\/00070\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/00313\/2020"],"award-info":[{"award-number":["UIDB\/00313\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PT2020\u2010PTDC\/QUI\u2010OUT\/29373\/2017"],"award-info":[{"award-number":["PT2020\u2010PTDC\/QUI\u2010OUT\/29373\/2017"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PT2020\u2010PTDC\/DTP\u2010FTO\/2784\/2014"],"award-info":[{"award-number":["PT2020\u2010PTDC\/DTP\u2010FTO\/2784\/2014"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["fellowship SFRH\/BD\/138873\/2018"],"award-info":[{"award-number":["fellowship SFRH\/BD\/138873\/2018"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pharmaceutics"],"abstract":"<jats:p>Caco-2 monolayers are a common in vitro model used to evaluate human intestinal absorption. The reference protocol requires 21 days post-seeding to establish a stable and confluent cell monolayer, which is used in a single permeability assay during the period of monolayer stability (up to day 30). In this work, we characterize variations in the tightness of the cell monolayer over the stable time interval and evaluate the conditions required for their re-use in permeability assays. The monolayer integrity was assessed through TEER measurements and permeability of the paracellular marker Lucifer Yellow (LY), complemented with nuclei and ZO-1 staining for morphological studies and the presence of tight junctions. Over 150 permeability assays were performed, which showed that manipulation of the cell monolayer in the permeability assay may contribute significantly to the flux of LY, leading to Papp values that are dependent on the sampling duration. The assay also leads to a small decrease in the cell monolayer TEER, which is fully recovered when cell monolayers are incubated with culture media for two full days. When this procedure is followed, the cell monolayers may be used for permeability assays on days 22, 25, and 28, triplicating the throughput of this important assay.<\/jats:p>","DOI":"10.3390\/pharmaceutics13101563","type":"journal-article","created":{"date-parts":[[2021,9,27]],"date-time":"2021-09-27T21:40:30Z","timestamp":1632778830000},"page":"1563","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":48,"title":["Re-Use of Caco-2 Monolayers in Permeability Assays\u2014Validation Regarding Cell Monolayer Integrity"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9098-5848","authenticated-orcid":false,"given":"Cristiana L.","family":"Pires","sequence":"first","affiliation":[{"name":"Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1669-0125","authenticated-orcid":false,"given":"Catarina","family":"Pra\u00e7a","sequence":"additional","affiliation":[{"name":"CNC\u2014Centro de Neuroci\u00eancias e Biologia Celular, CIBB\u2014Centro de Inova\u00e7\u00e3o em Biomedicina e Biotecnologia, Universidade de Coimbra, 3004-504 Coimbra, Portugal"},{"name":"Faculdade de Medicina, Universidade de Coimbra, 3000-370 Coimbra, Portugal"}]},{"given":"Patr\u00edcia A. T.","family":"Martins","sequence":"additional","affiliation":[{"name":"Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1280-3321","authenticated-orcid":false,"given":"Ana L. M.","family":"Batista de Carvalho","sequence":"additional","affiliation":[{"name":"Molecular Physical-Chemistry R&D Unit, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal"}]},{"given":"Lino","family":"Ferreira","sequence":"additional","affiliation":[{"name":"CNC\u2014Centro de Neuroci\u00eancias e Biologia Celular, CIBB\u2014Centro de Inova\u00e7\u00e3o em Biomedicina e Biotecnologia, Universidade de Coimbra, 3004-504 Coimbra, Portugal"},{"name":"Faculdade de Medicina, Universidade de Coimbra, 3000-370 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8391-0055","authenticated-orcid":false,"given":"Maria Paula M.","family":"Marques","sequence":"additional","affiliation":[{"name":"Molecular Physical-Chemistry R&D Unit, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal"},{"name":"Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3076-9905","authenticated-orcid":false,"given":"Maria Jo\u00e3o","family":"Moreno","sequence":"additional","affiliation":[{"name":"Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal"},{"name":"Faculdade de Medicina, Universidade de Coimbra, 3000-370 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1016\/S1359-6446(04)03354-9","article-title":"Cell culture-based models for intestinal permeability: A critique","volume":"10","author":"Balimane","year":"2005","journal-title":"Drug Discov. Today"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"539","DOI":"10.1080\/17460441.2020.1735347","article-title":"Advances in cell-based permeability assays to screen drugs for intestinal absorption","volume":"15","author":"Volpe","year":"2020","journal-title":"Expert Opin. Drug Discov."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"736","DOI":"10.1016\/S0016-5085(89)80072-1","article-title":"Characterization of the Human-Colon Carcinoma Cell-Line (Caco-2) as a Model System for Intestinal Epithelial Permeability","volume":"96","author":"Hidalgo","year":"1989","journal-title":"Gastroenterology"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"902","DOI":"10.1023\/A:1015937605100","article-title":"Caco-2 Cell Monolayers as a Model for Drug Transport Across the Intestinal-Mucosa","volume":"7","author":"Hilgers","year":"1990","journal-title":"Pharm. Res."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1517\/17425255.1.2.175","article-title":"Caco-2 cell permeability assays to measure drug absorption","volume":"1","author":"Li","year":"2005","journal-title":"Expert Opin. Drug Metab. Toxicol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"280","DOI":"10.1016\/j.addr.2012.09.005","article-title":"Caco-2 monolayers in experimental and theoretical predictions of drug transport","volume":"64","author":"Artursson","year":"2012","journal-title":"Adv. Drug Deliv. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1016\/0378-5173(95)04204-0","article-title":"Comparison between active and passive drug transport in human intestinal epithelial (Caco-2) cells in vitro and human jejunum in vivo","volume":"127","author":"Lennernas","year":"1996","journal-title":"Int. J. Pharmaceut."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"880","DOI":"10.1016\/0006-291X(91)91647-U","article-title":"Correlation Between Oral-Drug Absorption in Humans and Apparent Drug Permeability Coefficients in Human Intestinal Epithelial (Caco-2) Cells","volume":"175","author":"Artursson","year":"1991","journal-title":"Biochem. Biophys. Res. Commun."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"905","DOI":"10.1016\/j.drudis.2012.03.015","article-title":"Evidence-based approach to assess passive diffusion and carrier-mediated drug transport","volume":"17","author":"Di","year":"2012","journal-title":"Drug Discov. Today"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"395","DOI":"10.1517\/17425255.4.4.395","article-title":"The Caco-2 cell monolayer: Usefulness and limitations","volume":"4","author":"Sun","year":"2008","journal-title":"Expert Opin. Drug Metab. Toxicol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1976","DOI":"10.1016\/j.stemcr.2017.10.013","article-title":"Development and Characterization of a Human and Mouse Intestinal Epithelial Cell Monolayer Platform","volume":"9","author":"Kozuka","year":"2017","journal-title":"Stem Cell Rep."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1016\/j.vascn.2014.11.004","article-title":"Variability of permeability estimation from different protocols of subculture and transport experiments in cell monolayers","volume":"71","author":"Casabo","year":"2015","journal-title":"J. Pharmacol. Toxicol. Methods"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1016\/j.ejpb.2016.12.027","article-title":"Quantitative analysis of lab-to-lab variability in Caco-2 permeability assays","volume":"114","author":"Lee","year":"2017","journal-title":"Eur. J. Pharm. Biopharm."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10565-005-0085-6","article-title":"The Caco-2 cell line as a model of the intestinal barrier: Influence of cell and culture-related factors on Caco-2 cell functional characteristics","volume":"21","author":"Sambuy","year":"2005","journal-title":"Cell Biol. Toxicol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2111","DOI":"10.1038\/nprot.2007.303","article-title":"Determination of drug permeability and prediction of drug absorption in Caco-2 monolayers","volume":"2","author":"Hubatsch","year":"2007","journal-title":"Nat. Protoc."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"248","DOI":"10.3181\/00379727-214-44093","article-title":"The influence of culture time and passage number on the morphological and physiological development of Caco-2 cells","volume":"214","author":"BriskeAnderson","year":"1997","journal-title":"Proc. Soc. Exp. Biol. Med."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1021\/js950269u","article-title":"Transport properties are not altered across Caco-2 cells with heightened TEER despite underlying physiological and ultrastructural changes","volume":"85","author":"Lu","year":"1996","journal-title":"J. Pharm. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"336","DOI":"10.1002\/(SICI)1520-6017(200003)89:3<336::AID-JPS5>3.0.CO;2-M","article-title":"Evaluation of an accelerated Caco-2 cell permeability model","volume":"89","author":"Liang","year":"2000","journal-title":"J. Pharm. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"669","DOI":"10.1002\/jps.10050","article-title":"New and better protocols for a short-term Caco-2 cell culture system","volume":"91","author":"Yamashita","year":"2002","journal-title":"J. Pharm. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"334","DOI":"10.1016\/j.vascn.2013.07.004","article-title":"Accelerated Caco-2 cell permeability model for drug discovery","volume":"68","author":"Sevin","year":"2013","journal-title":"J. Pharmacol. Toxicol. Methods"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/j.vascn.2014.07.001","article-title":"Development, validation, and application of a novel 7-day Caco-2 cell culture system","volume":"70","author":"Cai","year":"2014","journal-title":"J. Pharmacol. Toxicol. Methods"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1016\/j.ijpharm.2005.03.008","article-title":"Validation of the 96 well Caco-2 cell culture model for high throughput permeability assessment of discovery compounds","volume":"297","author":"Marino","year":"2005","journal-title":"Int. J. Pharmaceut."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1016\/j.ejpb.2004.02.014","article-title":"Utility of 96 well Caco-2 cell system for increased throughput of P-gp screening in drug discovery","volume":"58","author":"Balimane","year":"2004","journal-title":"Eur. J. Pharm. Biopharm."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Sevin, E., Dehouck, L., Versele, R., Culot, M., and Gosselet, F. (2019). A Miniaturized Pump Out Method for Characterizing Molecule Interaction with ABC Transporters. Int. J. Mol. Sci., 20.","DOI":"10.3390\/ijms20225529"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1961","DOI":"10.1023\/B:PHAM.0000008043.71001.43","article-title":"Development of a 7-day, 96-well Caco-2 permeability assay with high-throughput direct UV compound analysis","volume":"20","author":"Alsenz","year":"2003","journal-title":"Pharm. Res."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1002\/(SICI)1097-0231(20000331)14:6<523::AID-RCM906>3.0.CO;2-T","article-title":"High-throughput Caco-2 cell permeability screening by cassette dosing and sample pooling approaches using direct injection\/on-line guard cartridge extraction\/tandem mass spectrometry","volume":"14","author":"Bu","year":"2000","journal-title":"Rapid Commun. Mass Spectrom."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1023\/A:1022262818573","article-title":"N-in-one permeability studies of heterogeneous sets of compounds across Caco-2 cell monolayers","volume":"20","author":"Laitinen","year":"2003","journal-title":"Pharm. Res."},{"key":"ref_28","first-page":"337","article-title":"Compound mixtures in Caco-2 cell permeability screens as a means to increase screening capacity","volume":"56","author":"Tannergren","year":"2001","journal-title":"Pharmazie"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"675","DOI":"10.1016\/j.tiv.2005.03.006","article-title":"Correlation of in vitro cytotoxicity with paracellular permeability in Caco-2 cells","volume":"19","author":"Konsoula","year":"2005","journal-title":"Toxicol. Vitr."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Rodrigues, E.T., Nascimento, S.F., Pires, C.L., Godinho, L.P., Churro, C., Moreno, M.J., and Pardal, M.A. (2021). Determination of intestinal absorption of the paralytic shellfish toxin GTX-5 using the Caco-2 human cell model. Environ. Sci. Pollut. Res.","DOI":"10.1007\/s11356-021-15342-y"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"757","DOI":"10.1023\/A:1012150405949","article-title":"Evidence for diminished functional expression of intestinal transporters in Caco-2 cell monolayers at high passages","volume":"14","author":"Yu","year":"1997","journal-title":"Pharm. Res."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"670","DOI":"10.1208\/s12248-010-9227-8","article-title":"Application of Method Suitability for Drug Permeability Classification","volume":"12","author":"Volpe","year":"2010","journal-title":"Aaps J."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"414","DOI":"10.1016\/0016-5085(92)90829-N","article-title":"Transient Mosaic Patterns of Morphological and Functional-Differentiation in the Caco-2 Cell-Line","volume":"103","author":"Vachon","year":"1992","journal-title":"Gastroenterology"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"564","DOI":"10.1016\/j.ejps.2012.07.005","article-title":"Evaluation of cytotoxicity of surfactants used in self-micro emulsifying drug delivery systems and their effects on paracellular transport in Caco-2 cell monolayer","volume":"47","author":"Ujhelyi","year":"2012","journal-title":"Eur. J. Pharm. Sci."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"101413","DOI":"10.1016\/j.jddst.2019.101413","article-title":"Papain-cyclodextrin complexes as an intestinal permeation enhancer: Permeability and in vitro safety evaluation","volume":"55","author":"Corazza","year":"2020","journal-title":"J. Drug Deliv. Sci. Technol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"340","DOI":"10.1016\/j.ejpb.2012.07.020","article-title":"Comparison of brain capillary endothelial cell-based and epithelial (MDCK-MDR1, Caco-2, and VB-Caco-2) cell-based surrogate blood-brain barrier penetration models","volume":"82","author":"Hellinger","year":"2012","journal-title":"Eur. J. Pharm. Biopharm."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"661","DOI":"10.1007\/s00249-021-01518-4","article-title":"Uncertainty in protein-ligand binding constants: Asymmetric confidence intervals versus standard errors","volume":"50","author":"Paketuryte","year":"2021","journal-title":"Eur. Biophys. J. Biophys. Lett."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1038\/nprot.2009.182","article-title":"Nonlinear least-squares data fitting in Excel spreadsheets","volume":"5","author":"Kemmer","year":"2010","journal-title":"Nat. Protoc."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1615\/CritRevTherDrugCarrierSyst.v14.i3.20","article-title":"A human colonic cell line sharing similarities with enterocytes as a model to examine oral absorption: Advantages and limitations of the Caco-2 model","volume":"14","author":"Delie","year":"1997","journal-title":"Crit. Rev. Ther. Drug Carr. Syst."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"385","DOI":"10.2174\/1568026013395010","article-title":"Assessing the absorption of new pharmaceuticals","volume":"1","author":"Hidalgo","year":"2001","journal-title":"Curr. Top. Med. Chem."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1146\/annurev.physiol.60.1.143","article-title":"Regulation of the movement of solutes across tight junctions","volume":"60","author":"Madara","year":"1998","journal-title":"Annu. Rev. Physiol."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Tervonen, A., Ihalainen, T.O., Nymark, S., and Hyttinen, J. (2019). Structural dynamics of tight junctions modulate the properties of the epithelial barrier. PLoS ONE, 14.","DOI":"10.1371\/journal.pone.0214876"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1529","DOI":"10.1002\/jps.2600831103","article-title":"Quantitative Approaches to Delineate Paracellular Diffusion in Cultured Epithelial-Cell Monolayers","volume":"83","author":"Adson","year":"1994","journal-title":"J. Pharm. Sci."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"893","DOI":"10.2174\/138920008786485119","article-title":"Permeability for Intestinal Absorption: Caco-2 Assay and Related Issues","volume":"9","author":"Press","year":"2008","journal-title":"Curr. Drug Metab."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"367","DOI":"10.2174\/1568026013394886","article-title":"Strategies for absorption screening in drug discovery and development","volume":"1","author":"Bohets","year":"2001","journal-title":"Curr. Top. Med. Chem."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"4636","DOI":"10.1021\/acs.molpharmaceut.9b00733","article-title":"The Permeation of Acamprosate Is Predominantly Caused by Paracellular Diffusion across Caco-2 Cell Monolayers: A Paracellular Modeling Approach","volume":"16","author":"Antonescu","year":"2019","journal-title":"Mol. Pharm."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1016\/S0196-9781(97)00002-8","article-title":"Transepithelial transport of oligopeptides in the human intestinal cell, Caco-2","volume":"18","author":"Shimizu","year":"1997","journal-title":"Peptides"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"763","DOI":"10.1023\/A:1012102522787","article-title":"In vitro permeability across Caco-2 cells (colonic) can predict in vivo (small intestinal) absorption in man\u2014Fact or myth","volume":"14","author":"Yee","year":"1997","journal-title":"Pharm. Res."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"476","DOI":"10.1002\/jps.2600790604","article-title":"Epithelial transport of drugs in cell culture. I: A model for studying the passive diffusion of drugs over intestinal absorbtive (Caco-2) cells","volume":"79","author":"Artursson","year":"1990","journal-title":"J. Pharm. Sci."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1442","DOI":"10.1021\/tx300221k","article-title":"Transport of Chlorpromazine in the Caco-2 Cell Permeability Assay: A Kinetic Study","volume":"25","author":"Broeders","year":"2012","journal-title":"Chem. Res. Toxicol."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1016\/0304-4165(90)90179-Z","article-title":"Transport of Bile-Acids In a Human Intestinal Epithelial-Cell Line, Caco-2","volume":"1035","author":"Hidalgo","year":"1990","journal-title":"Biochim. Biophys. Acta"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"885","DOI":"10.1023\/A:1016005212640","article-title":"Age-dependent expression of P-glycoprotein gp170 in Caco-2 cell monolayers","volume":"13","author":"Hosoya","year":"1996","journal-title":"Pharm. Res."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"749","DOI":"10.1023\/B:PHAM.0000026423.48583.e2","article-title":"Correction of permeability with pore radius of tight junctions in Caco-2 monolayers improves the prediction of the dose fraction of hydrophilic drugs absorbed by humans","volume":"21","author":"Saitoh","year":"2004","journal-title":"Pharm. Res."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"2166","DOI":"10.1002\/jps.21961","article-title":"Paracellular Porosity and Pore Size of the Human Intestinal Epithelium in Tissue and Cell Culture Models","volume":"99","author":"Linnankoski","year":"2010","journal-title":"J. Pharm. 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