title: 'Keratolytic' properties of benzoyl peroxide and retinoic acid resemble salicylic acid in man.
abstract: OBJECTIVE
  Retinoic acid (RA) and benzoyl peroxide (BP) were studied, comparing their keratolytic efficacy and water barrier disruption to that of salicylic acid (SA), a well-established keratolytic, under similar conditions.
  
  
  METHODS
  Six volunteers were included in this blinded study. Eleven randomized test sites were marked on the volar forearms, containing sites for untreated skin at time zero, unoccluded, occlusion, and vehicle controls for 3 and 6 h, and each of BP, RA, and SA solutions for 3 and 6 h. At each time point, occlusion at 5 of the test sites was removed, and chromameter measurements were performed over 30 min. Each site then underwent 25 stratum corneum (SC) tape strippings. At 1, 5, and 30 min after the last stripping at each site, TEWL measurements were performed. Quantitative protein analysis of the SC from the tapes was then performed.
  
  
  CONCLUSIONS
  after 3 h, bp was significantly more effective in disrupting sc cohesion than sa and ra, indicating bp is a moderate keratolytic agent in addition to its antimicrobial properties. After 6 h, all three agents were similarly effective in keratolysis. Barrier disruption, as measured by TEWL, paralleled depth of SC removal. SA tended to exhibit the greatest keratolytic efficacy superficially, hence its clinical effectiveness in superficial conditions such as comedonal acne, whereas BP was more effective at deeper levels, complimenting its antimicrobial effects and enabling it to treat deeper, more inflammatory lesions. None of the agents significantly affected skin erythema. These techniques provide a robust and rapid assay for in vivo keratolytic demonstration.
authors.affiliation: Department of Dermatology, University of California San Francisco, San Francisco, CA 94143-0989, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Waller
authors.forename: F
authors.initials: F
authors.lastname: Dreher
authors.forename: S
authors.initials: S
authors.lastname: Behnam
authors.forename: C
authors.initials: C
authors.lastname: Ford
authors.forename: C
authors.initials: C
authors.lastname: Lee
authors.forename: T
authors.initials: T
authors.lastname: Tiet
authors.forename: G D
authors.initials: GD
authors.lastname: Weinstein
authors.forename: H I
authors.initials: HI
authors.lastname: Maibach
mesh_terms: D000328:Adult; D001585:Benzoyl Peroxide / Q000494:pharmacology*; D001834:Body Water / Q000378:metabolism; D006801:Humans; D007641:Keratolytic Agents / Q000494:pharmacology*; D008875:Middle Aged; D020156:Salicylic Acid / Q000494:pharmacology*; D012867:Skin / Q000187:drug effects / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D007641:Keratolytic Agents; D014212:Tretinoin; D020156:Salicylic Acid; D001585:Benzoyl Peroxide