title: Is the thin layer of methyl aminolevulinate used during photodynamic therapy sufficient?
abstract: BACKGROUND
  If the recommended 1.0 mm layer of methyl aminolevulinate (MAL) is used during photodynamic therapy (PDT) of large areas with multiple actinic keratoses (AK) huge amounts of cream are needed.
  
  
  OBJECTIVE
  To report the amount of MAL used for PDT of AK and basal cell carcinomas (BCC) in daily routine. The association of protoporphyrin IX (PpIX) fluorescence and thickness of MAL was investigated in a randomized paired study in healthy volunteers.
  
  
  METHODS
  Amount of cream used per cm(2) during conventional and daylight PDT was recorded. In 16 healthy volunteers, 0.1 mm, 0.2 mm, 0.5 mm and 1.0 mm MAL cream were applied for 3 h on tape-stripped areas on each forearm randomized to light-permeable or light-impermeable occlusion. PpIX fluorescence was measured.
  
  
  RESULTS
  Less than 0.4 mm MAL was used during PDT of BCC and 0.2 mm for AK. No difference in PpIX fluorescence was found between the different thicknesses of MAL using light-impermeable occlusion.
  
  
  CONCLUSIONS
  In daily routine <0.4 mm MAL was used during PDT of BCC and 0.1-0.2 mm MAL during PDT of AK. The recommended 1.0 mm MAL did not result in a higher accumulation of PpIX compared to thinner MAL layers after light-impermeable occlusion for 3 h.
authors.affiliation: Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Stine R
authors.initials: SR
authors.lastname: Wiegell
authors.affiliation: Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Catharina M
authors.initials: CM
authors.lastname: Lerche
authors.affiliation: Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Hans Christian
authors.initials: HC
authors.lastname: Wulf
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000473:pathology; D000368:Aged; D000622:Aminolevulinic Acid / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D055623:Keratosis, Actinic / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D010778:Photochemotherapy / Q000379:methods*; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000473:pathology
chemical_list: D000622:Aminolevulinic Acid
keywords: actinic keratoses; basal cell carcinoma; methyl aminolevulinate; photodynamic therapy; protoporphyrin IX fluorescence