title: Determination of the protection efficacy and homogeneity of the distribution of sunscreens applied onto skin pre-treated with cosmetic products.
abstract: BACKGROUND
  The efficacy of sunscreens depends decisively on the homogeneity of its distribution on the skin surface, which is sensitively reflected by two spectroscopic data - the factor of inhomogeneity and the sum transmission - measured after tape stripping. The aim of this study was to investigate the influence of a skin pre-treatment with body lotion on the layout of the formulations.
  
  
  METHODS
  Six healthy volunteers were pre-treated using the body lotion, Nivea Body (Beiersdorf AG, Hamburg, Germany). The sunscreen was an oil/water (o/w) emulsion, Roc SPF 8 (RoC SA, Paris, France). The tape stripped tesa films were measured with a modified UV/VIS spectrometer Lambda 5 (PerkinElmer, Frankfurt/Main, Germany), the data of which were used to calculate both measurands.
  
  
  RESULTS
  The obtained results made clear that the original spectroscopic data must be corrected taking into account the changed amounts of horny layer particles removed with the individual tape strips after pre-treatment. As a consequence of the correction, the factors of inhomogeneity as well as the sum transmissions confirm a more homogeneous distribution of the applied sunscreen.
  
  
  CONCLUSIONS
  The findings confirm that the applied method is well suited to obtain information on the distribution of topically applied substances, and furthermore that the influence of the pre-treatment of the skin with the body lotion enhances the homogeneity of distribution and thus the sunscreen efficacy.
authors.affiliation: Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Weigmann
authors.forename: Maude Suisse
authors.initials: MS
authors.lastname: de Sainte Claire
authors.forename: Sabine
authors.initials: S
authors.lastname: Schanzer
authors.forename: Alexa
authors.initials: A
authors.lastname: Patzelt
authors.forename: Martina
authors.initials: M
authors.lastname: Meinke
authors.forename: Christina
authors.initials: C
authors.lastname: Antoniou
authors.forename: Wolfram
authors.initials: W
authors.lastname: Sterry
authors.forename: Jürgen
authors.initials: J
authors.lastname: Lademann
mesh_terms: D003358:Cosmetics / Q000008:administration & dosage*; D004357:Drug Synergism; D004655:Emulsions / Q000008:administration & dosage* / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D008297:Male; D012867:Skin / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D013473:Sunscreening Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D053832:Surgical Tape; D014466:Ultraviolet Rays; D055815:Young Adult
chemical_list: D003358:Cosmetics; D004655:Emulsions; D013473:Sunscreening Agents