Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Refined in vitro Models for Prediction of Intestinal Drug Transport: Role of pH and Extracellular Additives in the Caco-2 Cell Model
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Drug transport across the intestinal epithelium is roughly predicted from permeability values obtained from Caco-2 cell monolayers. This thesis examines the important role of pH and extracellular additives for increasing the reliability and predictivity of the in vitro screening system, Caco-2.

It was shown that the passive transport of ionizable compounds may be biased by a false efflux or uptake component, when applying a physiological pH-gradient across the membrane. pH also affected the amount of compound available at the transporter-binding site. Therefore, pH dependence should be considered in studies of such compounds and of drug-drug interactions involving efflux transporters. It was also shown that proton-dependent apical uptake or basolateral efflux should be studied both with and without a pH gradient over the whole monolayers.

The two extracellular additives, bovine serum albumin (BSA) and the solubilizing agent, Cremophor® EL, also influenced Caco-2 permeabilities. BSA applied to the receiver side increases, and to the donor side decreases drug permeation according to the drug’s protein binding capacity. Thus, the absorptive transport for both passive and active compounds is favoured, giving a physiologically sound improvement of the Caco-2 cell model. Inclusion of BSA increased both the predictivity and quality of permeability studies, particularly of highly lipophilic, BCS class II compounds. Passive and active transport processes could also be distinguished after accounting for unbound concentrations. The overall effect of Cremophor® EL on the permeability to a drug was compound-specific and probably dependent on micellar incorporation. Cremophor® EL can therefore not be recommended.

Neither pH nor BSA affect the functionality of transporters such as P-glycoprotein. However, efflux ratios of ionizable or protein bound drugs are altered in the presence of a pH-gradient or BSA, indicating that an experimental system without protein or pH gradient can over- or underestimate active and passive efflux in drug transport.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2005. , p. 83
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 14
Keywords [en]
Pharmacy, Caco-2 cells, membrane permeability, drug permeation, drug efflux ratios, drug uptake ratios, Cremophor EL, bovine serum albumin, pH-dependent permeability, drug transport
Keywords [sv]
FARMACI
National Category
Pharmaceutical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-5814ISBN: 91-554-6262-6 (print)OAI: oai:DiVA.org:uu-5814DiVA, id: diva2:166491
Public defence
2005-06-02, B22, Uppsala Biomediciniska centrum, Uppsala, 13:15
Opponent
Supervisors
Available from: 2005-05-12 Created: 2005-05-12 Last updated: 2018-01-13Bibliographically approved
List of papers
1. pH-Dependent bidirectional transport of weakly basic drugs across Caco-2 monolayers: Implication for drug-drug interactions.
Open this publication in new window or tab >>pH-Dependent bidirectional transport of weakly basic drugs across Caco-2 monolayers: Implication for drug-drug interactions.
2003 In: Pharmaceutical Research, Vol. 20, no 8, p. 1141-1148Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-93109 (URN)
Available from: 2005-05-12 Created: 2005-05-12Bibliographically approved
2. pH-Dependent passive and active transport of acidic drugs across Caco-2 cell monolayers
Open this publication in new window or tab >>pH-Dependent passive and active transport of acidic drugs across Caco-2 cell monolayers
2005 (English)In: European Journal of Pharmaceutical Sciences, ISSN 0928-0987, E-ISSN 1879-0720, Vol. 25, no 2-3, p. 211-220Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to investigate pH-dependent passive and active transport of acidic drugs across Caco-2 cells. Therefore, the bidirectional pH-dependent transport of two acidic drugs, indomethacin and salicylic acid, across Caco-2 cells was studied in the physiological pH range of the gastrointestinal tract. The transport of both drugs decreased with increased pH, as expected from the pH-partition hypothesis. Net absorption occurred when the basolateral pH exceeded the apical pH. Concentration dependence and transporter inhibition studies indicated passive transport for indomethacin and a mixture of pH-dependent passive and active influx for salicylic acid. Unexpectedly, active and passive drug transport results were indistinguishable in temperature dependency studies. The transport of salicylic acid (apical pH 5.0; basolateral pH 7.4) was partly blocked by inhibitors of the proton-dependent transporters MCT1 (SLC16A1) and OATP-B (SLC21A9, SLCO2B1). This study shows that the asymmetry in bidirectional transport of acidic drugs is affected by both passive and active components in the presence of pH gradients across Caco-2 cells. Thus, combined studies of concentration-dependency and transport-inhibition are preferred when acidic drug transport is studied in a pH gradient. The findings of this in vitro study can be extrapolated to in vivo situations involving an acidic microclimate.

Keywords
Biological Transport; Active, Caco-2 Cells, Cell Membrane/*metabolism, Cell Membrane Permeability/*drug effects, Humans, Hydrogen-Ion Concentration, Indomethacin/*pharmacokinetics, Research Support; Non-U.S. Gov't, Salicylic Acid/*pharmacokinetics
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-93110 (URN)10.1016/j.ejps.2005.02.009 (DOI)15911216 (PubMedID)
Available from: 2005-05-12 Created: 2005-05-12 Last updated: 2017-12-14Bibliographically approved
3. Impact of extracellular protein binding on active drug transport across Caco-2 cells
Open this publication in new window or tab >>Impact of extracellular protein binding on active drug transport across Caco-2 cells
Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:uu:diva-93111 (URN)
Available from: 2005-05-12 Created: 2005-05-12Bibliographically approved
4. Advantages and disadvantages of using bovine serum albumin and/or Cremophor EL as extracellular additives during transport studies of lipophilic compounds across Caco-2 monolayers
Open this publication in new window or tab >>Advantages and disadvantages of using bovine serum albumin and/or Cremophor EL as extracellular additives during transport studies of lipophilic compounds across Caco-2 monolayers
2007 (English)In: Journal of drug delivery science and technology, ISSN 1773-2247, Vol. 17, no 4, p. 259-266Article in journal (Refereed) Published
Abstract [en]

The effects of Cremophor EL (CEL) and bovine serum albumin (BSA) on the active and passive permeation of BCS class II compounds (felodipine, asimadoline) were studied across Caco-2 cells. The effect of BSA on either or both sides of the monolayers, apically applied CEL in the presence ofbasolateral BSA and the effect ofaddition of CEL on P-gp by the use ofquinidine were investigated. Presence of 4% BSA improved sink conditions and recovery from 60 to 95% for both felodipine and asimadoline. Efflux ratios obtained under comparable sink conditions, indicated that felodipine was transported by passive diffusion, while quinidine and asimadoline were transported actively. CEL decreased the transport rate for felodipine and asimadoline in the absorptive direction and increased in the secretory direction at different CEL concentrations, most likely due to the incorporation of drug into micelles. Our results indicate that inclusion of BSA is generally sufficient to increase the recovery for lipophilic BCS class II compounds. The overall effect of CEL on the permeability of a drug is compound specific and, therefore, less predictable and cannot be recommended.

Keywords
Physicochemical properties, Pharmacokinetics, Vertebrata, Mammalia, Ungulata, Artiodactyla, Pharmaceutical technology, Solubility, Castor oil, MDR-1 gene, Absorption, Drug, Lipophilic compound, Transport, Additive, Serum albumin, Ox, Animal
National Category
Pharmaceutical Sciences
Identifiers
urn:nbn:se:uu:diva-93112 (URN)000250032200005 ()
Available from: 2005-05-12 Created: 2005-05-12 Last updated: 2018-01-13Bibliographically approved

Open Access in DiVA

fulltext(1085 kB)3659 downloads
File information
File name FULLTEXT01.pdfFile size 1085 kBChecksum MD5
55aa0b0740faaf5a0d060ea8d7980da0652e1fd0599751c987153355e278da508945258f
Type fulltextMimetype application/pdf
Buy this publication >>

By organisation
Department of Pharmacy
Pharmaceutical Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 3659 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 2529 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf