The chemistry and synergy of benzoyl peroxide with clindamycin

Conflicts of interest: none declared. Sir, We read with interest the recent article by Langner et al.1 In an acne study, this group reported that topical clindamycin and benzoyl peroxide outperformed adapalene by several parameters. The authors failed to acknowledge the chemistry as benzoyl peroxide radicals, the most active form of benzoyl peroxide, are increased markedly when used in combination with chemical structures that contain a tertiary amine within their structure, such as clindamycin and erythromycin.2 Biologically, benzoyl peroxide used in combination with allylamine antifungal agents has broader antimicrobial activity against bacteria and yeast than either agent alone.3 This complies with the belief that benzoyl peroxide exerts its antibacterial activity by the interaction of oxidized radical intermediates with elements of the bacterial cells. This chemical reaction is fleeting and clinical response can be improved by keeping the two agents separate until mixing on the skin surface itself.2 3–4 In short, increased radical activity and enhanced biological effect by means of this mechanism suggest the possibility of biological synergism in antimicrobial therapy.4