<p>Dapsone has both anti-infammatory and antimicrobial properties. A combination of these activities may account for its efcacy in acne. Anti-infammatory efects include inhibition of neutrophil myeloperoxidase and eosinophil peroxidase activity, suppression of hypochlorous acid production, scavenging of reactive oxygen species, suppression of neutrophil activity, and inhibition of chemoattractant-induced signal transduction. Antimicrobial activity, similar to that of sulfones and sulfonamides, is by inhibition of bacterial dihydropteroate synthase in the folic acid metabolic pathway. This mechanism is efective against microorganisms synthesizing their own folic acid. In vitro susceptibility testing has demonstrated some activity for Dapsone against Propionibacterium species, including Propionibacterium acnes (P. acnes).</p>