Effect of Topical Benzoyl Peroxide/Clindamycin Versus Topical Clindamycin and Vehicle in the Reduction of Propionibacterium acnes

Propionibacterium acnes is one of the primary factors involved in the pathogenesis of acne vulgaris; proliferation of this bacteria is present in all patients with inflammatory lesions. Combination topical therapy with agents that have different but complementary antimicrobial mechanisms of action has the potential to increase efficacy and to prevent the emergence of resistant organisms. The onset of action and effectiveness of 3 topical preparations (benzoyl peroxide 5%/clindamycin phosphate 1% gel, clindamycin phosphate 1% solution, and vehicle gel) in reducing P acnes were compared in a randomized, open-label, evaluator-blinded, comparative trial involving 60 healthy volunteers who were free of acne but had high levels of facial P acnes. Treatment with benzoyl peroxide 5%/clindamycin phosphate 1% gel significantly (P1 log10/cm² from baseline (91% inhibition) 24 hours after application. Progressive declines were observed throughout the 2-week study period, with a 3 log10/cm² reduction (99.9% inhibition) from baseline in P acnes at the end of the 2-week treatment period. In contrast, significant (P