Pigmentary Changes Following Photodynamic Therapy with 5-aminolevulinic Acid or Methyl Aminolevulinate Cream

Kim, Sang Tae; Park, Jong Bin; Kim, Joon Hee; Lee, Kang Hoon; Han, Sang Hwa; Yang, Joon Sung; Suh, Kee Suck; Jang, Min Soo

Abstract

BACKGROUND
Several side effects such as pain, erythema, and hyperpigmentation have been reported following photodynamic therapy (PDT).
OBJECTIVE
We sought to compare the pigmentary changes induced by PDT with 5-aminolevulinic acid (ALA) and those induced by PDT with methyl aminolevulinate (MAL) in people with skin phototypes III-IV over a 6 month period.
METHODS
In ten healthy volunteers, six skin areas on the upper arm of each subject were treated with (A) ALA 20% in base cream without irradiation, (A1) MAL 16.8% without irradiation, (B), (B1) control vehicles, (C) ALA 20% in base cream, and (C1) MAL 16.8%. Areas (B), (B1), (C), and (C1) were irradiated at four hours after photosensitizer or vehicle application. Irradiation was administered twice with a 1 week interval. The effects on the skin were assessed by visual and colorimetric evaluations.
RESULTS
On (C) and (C1) areas, erythema and pigmentation were most pronounced at 30 minutes after the second irradiation. Erythema rapidly diminished but pigmentation persisted throughout the study. Erythema and pigmentation on (C)-treated areas were more prominent and prolonged than those on (C1)-treated areas.
CONCLUSION
In subjects with skin phototypes III-IV, pigmentation tends to last for more than 6 months after PDT. The ALA-treated skin areas developed more severe and prolonged erythema and pigmentation than the MAL-treated skin areas.