Photodynamic therapy for acne vulgaris: a critical review from basics to clinical practice: part II. Understanding parameters for acne treatment with photodynamic therapy.

Unlabelled: Photodynamic therapy requires a photosensitizer, oxygen, and activating light. For acne, pilosebaceous units are "target" structures. Porphyrins are synthesized in vivo from 5-aminolevulinic acid (ALA), particularly in pilosebaceous units. Different photosensitizers and drug delivery methods have been reported for acne treatment. There are a variety of porphyrin precursors with different pharmacokinetic properties. Among them, ALA and methyl-ester of ALA (MAL) are available for possible off-label treatment of acne vulgaris. In addition, various light sources, light dosimetry, drug incubation time, and pre- and posttreatment care also change efficacy and side effects. None of these variables has been optimized for acne treatment, but a number of clinical trials provide helpful guidance. In this paper, we critically analyze clinical trials, case reports, and series of cases published through 2009.

Learning Objectives: After completing this learning activity, participants should be able to analyze photodynamic therapy using 5-aminolevulinic acid and its derivates for acne treatment, predict the effectiveness and outcomes of photodynamic therapy using different parameters and/or different porphyrin-related photosensitizers, and assess and manage the side effects of porphyrin-based photodynamic therapy for acne.