title: Tacrolimus ointment neither blocks ultraviolet B nor affects expression of thymine dimers and p53 in human skin.
abstract: BACKGROUND
  There is a lack of data with regard to the interaction between ultraviolet (UV) radiation and topical calcineurin inhibitors.
  
  
  OBJECTIVE
  We aimed to investigate (1) the UV transmission through tacrolimus ointment and (2) the impact of topical exposure to tacrolimus on the protein expression of thymine dimers (TD) and p53 in human skin.
  
  
  METHODS
  Spectrophotometric measurements (290-400 nm) of tacrolimus ointment and the vehicle were performed. Eight subjects were treated with tacrolimus ointment and the vehicle thrice daily over a 3-day period on the back. Pre-treated sites and one control site were exposed to two minimal erythema doses UVB. Skin biopsies were taken 1h and 24h after irradiation. Immunohistochemical procedures were used for the detection of TD and p53.
  
  
  RESULTS
  Mean UV transmission was over 94% and did not significantly differ between tacrolimus ointment and the vehicle. Immunohistological examinations of TD and p53 expression did not demonstrate significant differences between irradiated sites, irradiated plus vehicle treated sites, and irradiated plus tacrolimus treated sites both 1h and 24h post-irradiation.
  
  
  CONCLUSIONS
  The present data suggest that tacrolimus ointment hardly has UV blocking capacities and does not significantly interfere with development and/or removal of local DNA damage in human skin.
authors.affiliation: Department of Dermatology and Allergology, Ruhr-University Bochum, Gudrunstrasse 56, 44791 Bochum, Germany. t.gambichler@klinikum-bochum.de
authors.forename: Thilo
authors.initials: T
authors.lastname: Gambichler
authors.forename: Axel
authors.initials: A
authors.lastname: Schlaffke
authors.forename: Nordwig S
authors.initials: NS
authors.lastname: Tomi
authors.forename: Nick
authors.initials: N
authors.lastname: Othlinghaus
authors.forename: Peter
authors.initials: P
authors.lastname: Altmeyer
authors.forename: Alexander
authors.initials: A
authors.lastname: Kreuter
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019703:Calcineurin / Q000378:metabolism; D065095:Calcineurin Inhibitors; D004249:DNA Damage / Q000187:drug effects*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009824:Ointments; D011740:Pyrimidine Dimers / Q000378:metabolism*; D012867:Skin / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D013056:Spectrophotometry, Ultraviolet; D016559:Tacrolimus / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D065095:Calcineurin Inhibitors; D009824:Ointments; D011740:Pyrimidine Dimers; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D019703:Calcineurin; D016559:Tacrolimus