Is topical dapsone safe in glucose-6-phosphate dehydrogenase-deficient and sulfonamide-allergic patients?

Topical dapsone gel 5% is indicated for the treatment of acne vulgaris and has been marketed since late 2008. The topical formulation retains the anti-inflammatory benefits of dapsone while minimizing the risk of toxicity associated with systemic exposure. This review summarizes the pharmacokinetic and safety data of topical dapsone gel 5% in acne patients, including those with glucose-6-phosphate dehydrogenase (G6PD) deficiency, and provides support for dapsone usage in sulfonamide-allergic patients. Overall, topical dapsone gel has a favorable short- and long-term safety profile and has been shown to have no risk of hemolytic anemia, including in G6PD deficient patients. Although there are some structural similarities between dapsone and sulfonamides, dapsone is not a sulfonamide and cross-reaction with sulfonamides has not been demonstrated.