title: Light protection of the skin after photodynamic therapy reduces inflammation: an unblinded randomized controlled study.
abstract: BACKGROUND
  Photodynamic therapy (PDT) is followed by significant inflammation. Protoporphyrin (Pp)IX is still formed in the skin after PDT and patients are sensitive to daylight 24-48 h after treatment. Exposure to daylight after PDT may therefore increase inflammation.
  
  
  OBJECTIVE
  To investigate whether protection with inorganic sunscreen, foundation or light-blocking plaster after PDT can reduce inflammation caused by daylight-activated PpIX.
  
  
  METHODS
  On the right arm of 15 subjects with sun-damaged skin, four identical squares (3 × 3 cm) were given conventional PDT treatment. Immediately after red-light illumination the squares were either left unprotected or protected by inorganic sunscreen [sun protection factor (SPF) 50], foundation (SPF50) or light-blocking plaster. The skin was then illuminated with artificial daylight for 2 h and afterwards covered for 24 h. Fluorescence and erythema (inflammation) were measured with a fluorescence camera and a reflectance meter.
  
  
  RESULTS
  PpIX was significantly reduced after artificial daylight illumination (P < 0·0004), except on the square protected with light-blocking silver plaster, where it had increased (P = 0·09). The increased erythema 24 h after treatment was reduced by 19% with the sunscreen (P = 0·29), by 27% with the foundation (P = 0·10) and by 44% with the silver plaster (P = 0·002).
  
  
  CONCLUSIONS
  Artificial daylight exposure after conventional PDT increases skin erythema. Light-blocking plaster gives more effective protection against post-PDT daylight exposure than inorganic sunscreen and foundation. In practice such full protection can be achieved by use of sun-blocking clothes or daylight avoidance for 24 h.
authors: Department of Dermatological Research, Copenhagen University, D92, Bispebjerg Hospital, Bispebjerg Bakke 23,, DK-2400, Copenhagen, Denmark.
authors: B
authors: B
authors: Petersen
authors: S R
authors: SR
authors: Wiegell
authors: H C
authors: HC
authors: Wulf
mesh_terms: D000622:Aminolevulinic Acid / Q000009:adverse effects; D003875:Drug Eruptions / Q000209:etiology / Q000517:prevention & control; D004890:Erythema / Q000209:etiology / Q000517:prevention & control; D005260:Female; D005453:Fluorescence; D006801:Humans; D055623:Keratosis, Actinic / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy / Q000009:adverse effects*; D010787:Photosensitivity Disorders / Q000139:chemically induced / Q000517:prevention & control*; D017319:Photosensitizing Agents / Q000009:adverse effects; D011524:Protoporphyrins / Q000378:metabolism; D013472:Sunlight / Q000009:adverse effects; D013473:Sunscreening Agents / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D017319:Photosensitizing Agents; D011524:Protoporphyrins; D013473:Sunscreening Agents; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX