Radiant near infrared light emitting Diode exposure as skin preparation to enhance photodynamic therapy inflammatory type acne treatment outcome

Abstract

An alternative approach in the treatment of acne vulgaris is photodynamic therapy (PDT) that uses light and aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) production to eradicate Propionibacterium acnes found in acne lesions. PpIX formation is dependent on ALA percutaneaous penetration. In this study, to enhance ALA penetration and subsequent accumulation of PpIX, skin temperature was increased with radiant infrared (IR) prior to ALA-PDT application and compared to ALA-PDT alone in the treatment of inflammatory acne. Ten patients exhibiting inflammatory acne with a lesion count of > or =10 were assigned to a split face or split back group. One side was pre-treated for 15 minutes with radiant IR light emitting diode (LED) (970 nm), while the other side was used as control. ALA was then applied after which PDT LED (630 nm) was performed on the entire face or back surface. Blinded lesion counts and clinical global assessment of severity were performed based on digital photographs before and 4 weeks after the PDT procedure. This randomized, controlled, and rater-blinded trial revealed a significant difference in median reduction of inflammatory lesions on the IR pre-treated (73%, 95% confidence interval (CI) 51-81%) versus the control side (38%, 95% CI 8-55%) 1 month after PDT (P<0.0001). Clinical assessment of severity was also significantly lower on the IR-treated side than on the control side (median 1, 95% CI 0.74-1.34 vs. 2, 95% CI 1.17-1.72). No unusual treatment-related adverse effects were observed. The reported therapeutic effects may be due to enhanced induction of alterations in transcutaneous diffusion kinetics of the photosensitizer at higher skin temperature and/or conversion of ALA to PpIX. Pre-PDT radiant IR LED exposure appears to be a promising method to enhance PDT efficacy for the treatment of acne lesions.