Due to the limited therapeutic options for severe acne vulgaris, researchers D.M. Pariser, MD, et al, investigated a new photodynamic therapy (PDT) treatment protocol using red light and methyl aminolevulinate (MAL).
The double-blind, randomized, vehicle-controlled multicenter trial enrolled 153 patients (aged 12-35 years) with severe facial acne, which was characterized as an Investigator’s Global Assessment (IGA) score of four; 25-75 inflammatory lesions with ≤ three nodules; and 20-100 non-inflammatory lesions. Topical MAL (80mg-1) was used as the photosensitizer. Treatment (four treatments, two weeks apart) involved incubation with MAL (n = 100) or vehicle cream (n = 53) for 90 minutes under occlusion, then illumination (635nm red light, total dose 37J cm-2). IGA assessment and standardized lesion counts were performed before each treatment and 12 weeks after the first treatment. Treatment success was defined as improvement from baseline in IGA by ≥ two grades at 12 weeks. Safety assessments were for pain (10-cm visual analogue scale immediately after illumination), erythema (four-point rating scale) and adverse events.
At 12 weeks, PDT using MAL reduced inflammatory lesions vs. vehicle PDT (mean percentage change -37.3% vs. -16.2%, p = 0.003). However, non-inflammatory lesions did not decrease significantly (mean percentage change -28.6% vs. -24.9%, p = 0.72). Overall treatment success rates were greater with PDT + MAL (44% vs. 26%, p = 0.013). Pain was low and manageable, and there was similar pain or erythema with successive treatments.
The study was published in the British Journal of Dermatology (April 2016).
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