Nonablative fractional laser as a tool to facilitate skin penetration of 5-aminolaevulinic acid with minimal skin disruption: a preliminary study

Abstract

Effective penetration of a photosensitizer is an essential step in photodynamic therapy (PDT). There have been trials of several methods, including laser treatment, to facilitate prompt and sufficiently deep transdermal drug delivery. To evaluate the effects of nonablative fractional laser pretreatment on 5-aminolaevulinic acid (ALA) penetration of the skin. Twelve treatment areas (1 × 1 cm(2)) on the backs of 10 healthy male subjects were mapped. Test areas received laser treatment followed by incubation with ALA. Laser treatment was performed with a 1550 nm fractional erbium glass laser, and the laser energy was set to 20 or 50 mJ with a spot density of 50 cm(-2). ALA incubation time was 30, 60 or 180 min. Porphyrin fluorescence was measured. Sites pretreated with nonablative fractional laser showed significantly increased porphyrin fluorescence compared with nonpretreated areas. Laser energy strength and ALA incubation time were positively correlated with ALA absorption. Nonablative fractional laser treatment effectively enhanced ALA skin penetration. Pretreatment with a nonablative fractional laser can be used for ALA-PDT to achieve higher ALA uptake and shortened ALA incubation times with minimal skin barrier disruption compared with ablative laser.