The relation between methyl aminolevulinate concentration and inflammation after photodynamic therapy in healthy volunteers.
Inflammation and pain are well known adverse-effects in photodynamic therapy (PDT). There is currently a tendency towards introducing lower concentrations of the photosensitizer than used in the standard treatment for various indications. The aim of this study was to investigate whether reduced concentrations of methyl aminolevulinate (MAL) can reduce inflammation (erythema) during PDT treatment. We measured the formation of protoporphyrin IX (PpIX) using fluorescence and monitored both erythema and pain during and after PDT treatment with conventional 16% MAL and threee reduced concentrations of 2, 0.75, and 0.25% in twenty-four healthy volunteers. We found that lowering the MAL concentration reduced PpIX fluorescence and erythema after PDT treatment. There was a strong correlation (R(2) = 0.70) between the PpIX fluorescence and erythema after treatment. A further increase in erythema after PDT was dependent on pre-treatment skin erythema. PpIX fluorescence could explain 70% of the increase in erythema (P < 0.0005). Pain and post-treatment hyperpigmentation can be reduced but not eliminated by limiting the MAL concentration. An efficacy study of PDT with these three reduced concentrations has not been performed.
Department of Dermatology, Odense University Hospital, Denmark.
Susanne
S
Fabricius
Catharina Margrethe
CM
Lerche
Peter Alshede
PA
Philipsen
Hans Christian
HC
Wulf
D000328:Adult; D000622:Aminolevulinic Acid / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004890:Erythema / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017288:Pain Threshold / Q000187:drug effects / Q000528:radiation effects; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000009:adverse effects / Q000627:therapeutic use*; D012880:Skin Pigmentation / Q000187:drug effects / Q000528:radiation effects; D013050:Spectrometry, Fluorescence
D017319:Photosensitizing Agents; C475457:methyl 5-aminolevulinate; D000622:Aminolevulinic Acid