ACNE P100 Efficacy of benzoyl peroxide (5.3%) emollient foam and benzoyl peroxide (8%) wash in reducing propionibacterium acnes on the back James Leyden, MD, KGL, INC. (Skin Study Center), Broomall, Pennsylvania, United States BACKGROUND: A benzoyl peroxide (BP) emollient foam is suited for broad body surface areas and offers a treatment alternative to a BP wash for body acne. BP exerts its therapeutic effect in acne through the reduction of P. acnes as has been previously demonstrated by a 1.0 to 2.0 logarithmic colony reduction on the face, with leave-on formulations achieving greater reductions than wash-off formulations. Prior to this trial, no data on P. acnes reduction on the back existed for any BP formulations or other acne treatments. OBJECTIVES: To evaluate the effectiveness of topical BP (5.3%) emollient foam and a BP (8%) wash in reducing P. acnes levels on the back. METHODS: A 5-week open-label single center study of 20 healthy subjects (>18 years old), colonized with P. acnes on their backs (>10,000 colonies per cm2). Each subject was treated once daily with BP emollient foam on the back during the first two weeks. Subjects received no treatment in week 3 and were subsequently instructed to apply BP wash during weeks 4 and 5 at least once daily in the shower to the same area of the back treated with BP emollient foam. Quantitative bacteriologic cultures were obtained at baseline and weeks 1, 2, 3, 4 and 5. RESULTS: 19 patients were evaluable. Total P. acnes counts were reduced by 1.9 log after 1 week of treatment with BP emollient foam, and by 2.1 log after 2 weeks of treatment with BP emollient foam. P. acnes counts increased during the week of no treatment. Subsequent treatment with BP wash for two weeks showed no reduction in P. acnes counts from this new baseline. DISCUSSION: The leave-on BP emollient foam was superior to BP wash in reducing P. acnes populations on the backs of subjects. The lack of effect of BP wash in reducing P. acnes levels on the back is surprising in view of the demonstrated results on the face and warrants further study. CONCLUSIONS: BP (5.3%) emollient foam effectively reduced P. acnes populations on the back and may offer a useful therapy for patients with acne on broad body surface areas, such as the back. BP (8%) wash applied in the shower did not effectively reduce P. acnes populations on the back. Commercial Support: 100% is sponsored by Onset Therapeutics

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