title: The effect of urea and taurine as hydrophilic penetration enhancers on stratum corneum lipid models.
abstract: To optimize transdermal application of drugs, the barrier function of the skin, especially the stratum corneum (SC), needs to be reduced reversibly. For this purpose, penetration enhancers like urea or taurine are applied. Until now, it is unclear if this penetration enhancement is caused by an interaction with the SC lipid matrix or related to effects within the corneocytes. Therefore, the effects of both hydrophilic enhancers on SC models with different dimensionality, ranging from monolayers to multilayers, have been investigated in this study. Many sophisticated methods were applied to ascertain the mode of action of both substances on a molecular scale. The experiments reveal that there is no specific interaction when 10% urea or 5% taurine solutions are added to the SC model systems. No additional water uptake in the head group region and no decrease of the lipid chain packing density have been observed. Consequently, we suppose that the penetration enhancing effect of both substances might be based on the introduction of large amounts of water into the corneocytes, caused by the enormous water binding capacity of urea and a resulting osmotic pressure in case of taurine.
authors.affiliation: Department of Pharmaceutics and Biopharmaceutics, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Mueller
authors.affiliation: Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, Am Mühlenberg 1, 14476 Potsdam, Germany.
authors.forename: J S L
authors.initials: JSL
authors.lastname: Oliveira
authors.affiliation: Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France.
authors.forename: R
authors.initials: R
authors.lastname: Barker
authors.affiliation: Institute Soft Matter and Functional Materials, Helmholtz-Zentrum-Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Trapp
authors.affiliation: Department of Pharmaceutics and Biopharmaceutics, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schroeter
authors.affiliation: Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, Am Mühlenberg 1, 14476 Potsdam, Germany. Electronic address: brezesinski@mpikg.mpg.de.
authors.forename: G
authors.initials: G
authors.lastname: Brezesinski
authors.affiliation: Department of Pharmaceutics and Biopharmaceutics, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany. Electronic address: reinhard.neubert@pharmazie.uni-halle.de.
authors.forename: R H H
authors.initials: RHH
authors.lastname: Neubert
mesh_terms: D000279:Administration, Cutaneous; D006801:Humans; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D010539:Permeability; D012867:Skin / Q000737:chemistry* / Q000378:metabolism; D013654:Taurine / Q000737:chemistry* / Q000493:pharmacokinetics; D014508:Urea / Q000737:chemistry* / Q000493:pharmacokinetics
chemical_list: D008563:Membrane Lipids; D013654:Taurine; D014508:Urea
keywords: Mode of action; Model membrane; Penetration enhancer; Stratum corneum lipids; Transdermal drug delivery