Pharmaceutical Research

, Volume 25, Issue 6, pp 1412–1419 | Cite as

Mechanistic Analysis of Chemical Permeation Enhancers for Oral Drug Delivery

  • Kathryn Whitehead
  • Samir MitragotriEmail author
Research Paper



Traditionally, the oral route cannot be employed for the delivery of macromolecular drugs such as proteins and peptides due, in large part, to limited transport across the epithelial membrane. This particular challenge can potentially be addressed through the use of chemical permeation enhancers, which affect transcellular and/or paracellular transport routes. Although certain permeation enhancers have been proposed for use in oral delivery, potential for application is often unclear when the route of enhancer action is unknown.


A combination of theory and experiments was developed for determining mechanism of enhancer action. The effect of 51 enhancers on Caco-2 cells was studied using TEER, MTT, and LDH assays.


The mechanistic details of intestinal permeability enhancement were uncovered for a broad set of enhancers in vitro. Understanding gained from enhancer mechanisms enabled the deduction of structure–function relationships for hydrophilic and hydrophobic permeation enhancers as well as the identification of a transcellular enhancer, 0.01% (w/v) palmityldimethyl ammonio propane sulfonate, which enabled the non-cytotoxic intracellular delivery of a model drug.


The results presented here emphasize the importance of understanding enhancer mechanism and uncover a zwitterionic surfactant capable of safely and effectively achieving intraepithelial drug delivery in vitro.

Key words

Caco-2 mechanism oral drug delivery permeation enhancer transcellular 



Enhancement potential


Mechanistic parameter


Lactate dehydrogenase

Log P

Water-octanol partion coefficient


LDH potential


Methyl thiazole tetrazolium


Palmityldimethyl ammonio propane sulfonate


Transepithelial electrical resistance


Toxicity potential



This work was supported by a fellowship to KW from the Graduate Research and Education in Adaptive bio-Technology (GREAT) Training Program by the University of California Biotechnology Research and Education Program and by the American Diabetes Association. The authors would also like to thank Natalie Karr for technical assistance.

Supplementary material

11095_2008_9542_MOESM1_ESM.doc (306 kb)
Supplementary Material (DOC 360 KB)


  1. 1.
    S. K. Kim, D. Y. Lee, E. Lee, Y.-k. Lee, C. Y. Kim, H. T. Moon, and Y. Byun. Absorption study of deoxycholic acid–heparin conjugate as a new form of oral anti-coagulant. J. Control. Rel. 120:4–10 (2007).CrossRefGoogle Scholar
  2. 2.
    K. M. Wood, G. Stone, and N. A. Peppas. Lectin functionalized complexation hydrogels for oral protein delivery. J. Control. Rel. 116:e66–e68 (2006).CrossRefGoogle Scholar
  3. 3.
    M. Goldberg, and I. Gomez-Orellana. Challenges for the oral delivery of macromolecules. Nat. Rev. Drug. Discov. 2:289–295 (2003).PubMedCrossRefGoogle Scholar
  4. 4.
    B. J. Aungst. Intestinal permeation enhancers. J. Pharm. Sci 89:429–442 (2000).PubMedCrossRefGoogle Scholar
  5. 5.
    N. N. Salama, N. D. Eddington, and A. Fasano. Tight junction modulation and its relationship to drug delivery. Adv. Drug. Deliv. Rev. 58:15–28 (2006).PubMedCrossRefGoogle Scholar
  6. 6.
    D. Bourdet, G. Pollack, and D. Thakker. Intestinal absorptive transport of the hydrophilic cation ranitidine: A kinetic modeling approach to elucidate the role of uptake and efflux transporters and paracellular vs. transcellular transport in Caco-2 cells. Pharm. Res. 23:1178–1187 (2006).PubMedCrossRefGoogle Scholar
  7. 7.
    S. Maher, L. Feighery, D. Brayden, and S. McClean. Melittin as an epithelial permeability enhancer I: Investigation of its mechanism of action in Caco-2 monolayers. Pharm. Res. 24:1336–1345 (2007).PubMedCrossRefGoogle Scholar
  8. 8.
    C. M. Meaney, and C. M. O’Driscoll. A comparison of the permeation enhancement potential of simple bile salt and mixed bile salt: Fatty acid micellar systems using the Caco-2 cell culture model. Int. J. Pharm. Sci. 207:21–30 (2000).CrossRefGoogle Scholar
  9. 9.
    T. Shimazaki, M. Tomita, S. Sadahiro, M. Hayashi, and S. Awazu. Absorption-enhancing effects of sodium caprate and palmitoyl carnitine in rat and human colons. Dig. Dis. Sci. 43:641–645 (1998).PubMedCrossRefGoogle Scholar
  10. 10.
    S. M. van der Merwe, J. C. Verhoef, J. H. M. Verheijden, A. F. Kotze, and H. E. Junginger. Trimethylated chitosan as polymeric absorption enhancer for improved peroral delivery of peptide drugs. Eur. J. Pharm. Biopharm. 58:225–235 (2004).PubMedCrossRefGoogle Scholar
  11. 11.
    A. C. Chao, J. V. Nguyen, M. Broughall, J. Recchia, C. R. Kensil, P. E. Daddona, and J. A. Fix. Enhancement of intestinal model compound transport by DS-1, a modified Quillaja saponin. J. Pharm. Sci. 87:1395–1399 (1998).PubMedCrossRefGoogle Scholar
  12. 12.
    T. Suzuki, and H. Hara. Difructose anhydride III and sodium caprate activate paracellular transport via different intracellular events in Caco-2 cells. Life Sciences 79:401–410 (2006).PubMedCrossRefGoogle Scholar
  13. 13.
    E. Duizer, C. Van Der Wulp, C. H. M. Versantvoort, and J. P. Groten. Absorption enhancement, structural changes in tight junctions and cytotoxicity caused by palmitoyl carnitine in Caco-2 and IEC-18 cells. J. Pharmacol. Exp. Ther. 287:395–402 (1998).PubMedGoogle Scholar
  14. 14.
    S. Hess, V. Rotshild, and A. Hoffman. Investigation of the enhancing mechanism of sodium n-[8-(2-hydroxybenzoyl)amino]caprylate effect on the intestinal permeability of polar molecules utilizing a voltage clamp method. Eur. J. Pharm. Sci. 25:307–312 (2005).PubMedGoogle Scholar
  15. 15.
    T. Uchiyama, T. Sugiyama, Y. S. Quan, A. Kotani, N. Okada, T. Fujita, S. Muranishi, and A. Yamamoto. Enhanced permeability of insulin across the rat intestinal membrane by various absorption enhancers: Their intestinal mucosal toxicity and absorption-enhancing mechanism of n-lauryl-beta-D-maltopyranoside. J. Pharm. Pharmacol. 51:1241–1250 (1999).PubMedCrossRefGoogle Scholar
  16. 16.
    P. Sharma, M. V. S. Varma, H. P. S. Chawla, and R. Panchagnula. Relationship between lipophilicity of BCS class III and IV drugs and the functional activity of peroral absorption enhancers. Il Farmaco. 60:870–873 (2005).PubMedCrossRefGoogle Scholar
  17. 17.
    A. A. Raoof, Z. Ramtoola, B. McKenna, R. Z. Yu, G. Hardee, and R. S. Geary. Effect of sodium caprate on the intestinal absorption of two modified antisense oligonucleotides in pigs. Eur. J. Pharm. Sci. 17:131–138 (2002).PubMedCrossRefGoogle Scholar
  18. 18.
    T. W. Leonard, J. Lynch, M. J. McKenna, and D. J. Brayden. Promoting absorption of drugs in humans using medium-chain fatty acid-based solid dosage forms: GIPET. Expert. Opin. Drug Deliv. 3:685–692 (2006).PubMedCrossRefGoogle Scholar
  19. 19.
    E. K. Anderberg, T. Lindmark, and P. Artursson. Sodium caprate elicits dilatations in human intestinal tight junctions and enhances drug absorption by the paracellular route. Pharm. Res. 10:857–864 (1993).PubMedCrossRefGoogle Scholar
  20. 20.
    J. D. Soderholm, H. Oman, L. Blomquist, J. Veen, T. Lindmark, and G. Olaison. Reversible increase in tight junction permeability to macromolecules in rat ileal mucosa in vitro by sodium caprate, a constituent of milk fat. Dig. Dis. Sci. 43:1547–1552 (1998).PubMedCrossRefGoogle Scholar
  21. 21.
    M. Tomita, M. Hayashi, T. Horie, T. Ishizawa, and S. Awazu. Enhancement of colonic drug absorption by the transcellular permeation route. Pharm. Res. 5:786–789 (1988).PubMedCrossRefGoogle Scholar
  22. 22.
    P. Sharma, M. V. S. Varma, H. P. S. Chawla, and R. Panchagnula. In situ and in vivo efficacy of peroral absorption enhancers in rats and correlation to in vitro mechanistic studies. Il Farmaco. 60:874–883 (2005).PubMedCrossRefGoogle Scholar
  23. 23.
    M. Sakai, T. Imai, H. Ohtake, H. Azuma, and M. Otagiri. Effects of absorption enhancers on the transport of model compounds in Caco-2 cell monolayers: Assessment by confocal laser scanning microscopy. J. Pharm. Sci. 86:779–785 (1997).PubMedCrossRefGoogle Scholar
  24. 24.
    M. Tomita, M. Hayashi, and S. Awazu. Absorption-enhancing mechanism of EDTA, caprate, and decanoylcarnitine in Caco-2 cells. J. Pharm. Sci. 85:608–611 (1996).PubMedCrossRefGoogle Scholar
  25. 25.
    E. Fuller, C. Duckham, and E. Wood. Disruption of epithelial tight junctions by yeast enhances the paracellular delivery of a model protein. Pharm. Res. 24:37–47 (2007).PubMedCrossRefGoogle Scholar
  26. 26.
    K. Whitehead, N. Karr, and S. Mitragotri. Safe and effective enhancers for oral drug delivery. Pharm Res. in press. DOI  10.1007/s11095-007-9488-9.
  27. 27.
    N. A. Motlekar, K. S. Srivenugopal, M. S. Wachtel, and B.-B. C. Youan. Oral delivery of low-molecular-weight heparin using sodium caprate as absorption enhancer reaches therapeutic levels. J. Drug Target 13:573–583 (2005).PubMedCrossRefGoogle Scholar
  28. 28.
    B. Aspenstrom-Fagerlund, L. Ring, P. Aspenstrom, J. Tallkvist, N.-G. Ilback, and A. W. Glynn. Oleic acid and docosahexaenoic acid cause an increase in the paracellular absorption of hydrophilic compounds in an experimental model of human absorptive enterocytes. Toxicology 237:12–23 (2007).PubMedCrossRefGoogle Scholar
  29. 29.
    G. Fotakis, and J. A. Timbrell. in vitro cytotoxicity assays: Comparison of LDH, neutral red, MTT and protein assay in hepatoma cell lines following exposure to cadmium chloride. Toxicol. Let. 160:171–177 (2006).CrossRefGoogle Scholar
  30. 30.
    E. S. Swenson, and W. Curatolo. Intestinal permeability enhancement for proteins, peptides, and other polar drugs: Mechanisms and potential toxicity. Adv. Drug Deliv. Rev. 8:39–92 (1992).CrossRefGoogle Scholar
  31. 31.
    W. P. Soutter, P. Sasieni, and T. Panoskaltsis. Long-term risk of invasive cervical cancer after treatment of squamous cervical intraepithelial neoplasia. Int. J. Cancer 118:2048–2055 (2006).PubMedCrossRefGoogle Scholar
  32. 32.
    C. Pilette, B. Colinet, R. Kiss, S. Andre, H. Kaltner, H. J. Gabius, M. Delos, J. P. Vaerman, M. Decramer, and Y. Sibille. Increased galectin-3 expression and intraepithelial neutrophils in small airways in severe chronic obstructive pulmonary disease. Eur. Respir. J. 29:914-922 (2007). DOI  09031936.00073005.Google Scholar
  33. 33.
    K. Ishida, M. Takaai, and Y. Hashimoto. Pharmacokinetic analysis of transcellular transport of quinidine across monolayers of human intestinal epithelial Caco-2 cells. Biol. Pharm. Bull. 29:522–526 (2006).PubMedCrossRefGoogle Scholar
  34. 34.
    A. Fasano, and J. P. Nataro. Intestinal epithelial tight junctions as targets for enteric bacteria-derived toxins. Adv. Drug Deliv. Rev. 56:795–807 (2004).PubMedCrossRefGoogle Scholar
  35. 35.
    T. Lindmark, T. Nikkila, and P. Artursson. Absorption enhancement through intracellular regulation of tight junction permeability by medium chain fatty acids in Caco-2 cells. J. Pharmacol. Exp. Ther. 284:362–369 (1998).PubMedGoogle Scholar
  36. 36.
    A. Marin, H. Sun, G. A. Husseini, W. G. Pitt, D. A. Christensen, and N. Y. Rapoport. Drug delivery in pluronic micelles: Effect of high-frequency ultrasound on drug release from micelles and intracellular uptake. J. Control. Rel. 84:39–47 (2002).CrossRefGoogle Scholar
  37. 37.
    D. M. Hallow, A. D. Mahajan, and M. R. Prausnitz. Ultrasonically targeted delivery into endothelial and smooth muscle cells in ex vivo arteries. J. Control. Rel. 118:285–293 (2007).CrossRefGoogle Scholar
  38. 38.
    E. B. Ghartey-Tagoe, J. S. Morgan, K. Ahmed, A. S. Neish, and M. R. Prausnitz. Electroporation-mediated delivery of molecules to model intestinal epithelia. Int. J. Pharm. Sci. 270:127–138 (2004).CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Department of Chemical EngineeringUniversity of CaliforniaSanta BarbaraUSA

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