title: Influence of drug treatment on the microacidity in rat and human skin--an in vitro electron spin resonance imaging study.
abstract: OBJECTIVE
  The possibilities of the noninvasive examination of microacidity (5) in different depths of the skin in vitro was explored, and the impact of drug treatment on the pH inside the skin was studied.
  
  
  METHODS
  Spectral-spatial electron spin resonance imaging (ss-ESRI) and pH-sensitive nitroxides were used to obtain a pH map of rat and human skin in vitro.
  
  
  RESULTS
  The dermal application of therapeutically used acids, such as salicylic acid and azelaic acid, caused a plain change of microacidity (pH) inside the skin. Species-linked differences between rat and human skin samples with respect to penetration and microacidity were found.
  
  
  CONCLUSIONS
  ESRI has been shown to be a new and completely noninvasive method to monitor microacidity in different skin layers and on the skin surface. This nondestructive method allows serial measurements on skin samples to be performed without any preparatory steps.
authors.affiliation: Department of Pharmacy, Humboldt University of Berlin, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Kroll
authors.forename: W
authors.initials: W
authors.lastname: Hermann
authors.forename: R
authors.initials: R
authors.lastname: Stösser
authors.forename: H H
authors.initials: HH
authors.lastname: Borchert
authors.forename: K
authors.initials: K
authors.lastname: Mäder
mesh_terms: D000818:Animals; D003879:Dermatologic Agents / Q000008:administration & dosage; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000737:chemistry* / Q000187:drug effects; D012869:Skin Absorption / Q000502:physiology; D012879:Skin Physiological Phenomena / Q000187:drug effects
chemical_list: D003879:Dermatologic Agents