title: Dose dependent sun protective effect of topical melatonin: A randomized, placebo-controlled, double-blind study.
abstract: BACKGROUND
  Ultraviolet radiation (UVR) by sunlight results in an increasing number of skin conditions. Earlier studies have suggested a protective effect of topical treatment with the pineal hormone melatonin. However, this protective effect has never been evaluated in natural sunlight, and the optimal dosing has not been clarified.
  
  
  OBJECTIVE
  The aim of this study was to investigate the sun protective effect of topical treatment with three different doses of melatonin (0.5%, 2.5%, 12.5%) against erythema induced by natural sunlight.
  
  
  METHODS
  The study was a randomized, placebo-controlled, double-blind study in healthy volunteers. Twenty-three healthy volunteers, 8 male and 15 female, were enrolled. The protective effect of three different doses of melatonin cream (0.5%, 2.5%, 12.5%) against erythema induced by natural sunlight was tested. All participants had their backs exposed to sun from 1:22 PM to 2:02 PM local time and UV-index was 9. Primary outcome was reduction in erythema evaluated by chromatography after sun exposure, when treated with topical melatonin cream (0.5%, 2.5%, 12.5%) versus placebo and no treatment. The erythema reaction was evaluated with chromatography and visual scoring at baseline, one, four, eight and 24h after exposure.
  
  
  RESULTS
  Significant difference in erythema formation was found between areas treated with melatonin cream 12.5% and areas receiving placebo or no treatment (repeated measures ANOVA p=0.001). No differences were found between placebo and the 0.5% and 2.5% concentrations.
  
  
  CONCLUSIONS
  Application of melatonin cream 12.5% protects against natural sunlight induced erythema.
authors.affiliation: Køge Hospital - University of Copenhagen, Department of Surgery, Lykkebækvej 1, DK-4600 Køge, Denmark. Electronic address: cili_scheuer@hotmail.com.
authors.forename: Cecilie
authors.initials: C
authors.lastname: Scheuer
authors.affiliation: Herlev Hospital - University of Copenhagen, Department of Surgery, Herlev Ringvej 75, DK- 2730 Herlev, Denmark; Hvidovre Hospital - University of Copenhagen, Department of Surgery, Kettegård Alle 30, DK - 2650 Hvidovre, Denmark.
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Pommergaard
authors.affiliation: Herlev Hospital - University of Copenhagen, Department of Surgery, Herlev Ringvej 75, DK- 2730 Herlev, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: Rosenberg
authors.affiliation: Køge Hospital - University of Copenhagen, Department of Surgery, Lykkebækvej 1, DK-4600 Køge, Denmark.
authors.forename: Ismail
authors.initials: I
authors.lastname: Gögenur
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000975:Antioxidants / Q000737:chemistry; D004307:Dose-Response Relationship, Radiation; D004311:Double-Blind Method; D004890:Erythema / Q000188:drug therapy*; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000188:drug therapy; D008297:Male; D008550:Melatonin / Q000008:administration & dosage* / Q000627:therapeutic use*; D008875:Middle Aged; D010870:Pineal Gland / Q000378:metabolism; D013472:Sunlight; D013473:Sunscreening Agents / Q000008:administration & dosage* / Q000627:therapeutic use*; D013997:Time Factors; D016896:Treatment Outcome; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D013473:Sunscreening Agents; D008550:Melatonin
keywords: Natural sun exposure; Non-melanoma skincancer; Topical melatonin