title: Biology of percutaneous penetration.
abstract: BACKGROUND
  Percutaneous penetration is a passive process that can occur following skin exposure to chemicals used in agriculture, industry, pharmaceuticals, cosmetics, and in the household. Once a penetrant is absorbed into the skin it may cause a local reaction or enter systemic circulation to produce widespread effects. Improved understanding of the skin barrier and biological aspects that impede absorption of topical substances is essential for advancing the fields of dermatotoxicology and dermatopharmacology as they pertain to percutaneous penetration.
  
  
  METHODS
  Pubmed search results for "percutaneous penetration", "absorption", "stratum corneum", "xenobiotics", "skin factors", "decontamination", and "transdermal" were reviewed from 1965 to 2014. Relevant articles discussing the influence of biological factors on percutaneous penetration of topical substances were included.
  
  
  RESULTS
  Absorption of a topical substance across the skin is most notably influenced by concentration, contact duration, frequency, and the surface area exposed. The interplay between these factors, along with skin biology and the physiochemical properties of the penetrant, can lead to enhanced percutaneous penetration.
  
  
  CONCLUSIONS
  Percutaneous penetration is a highly complicated and dynamic process influenced by numerous skin and environmental factors. Although research over the last few decades has provided plenty of new insights to improve our understanding of percutaneous penetration, many areas lack clarity due to conflicting data.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Blickenstaff
authors.forename: Garrett
authors.initials: G
authors.lastname: Coman
authors.forename: Collin M
authors.initials: CM
authors.lastname: Blattner
authors.forename: Rosa
authors.initials: R
authors.lastname: Andersen
authors.forename: Howard I
authors.initials: HI
authors.lastname: Maibach
mesh_terms: D000375:Aging / Q000502:physiology; D001711:Biotransformation; D006801:Humans; D008055:Lipids; D010599:Pharmacokinetics; D012869:Skin Absorption
chemical_list: D008055:Lipids