Dapsone (5% w/w) is a topical formulation of the sulfone antibiotic dapsone, primarily used in the management of inflammatory acne vulgaris. It exerts anti-inflammatory and antimicrobial effects, specifically targeting the neutrophilic inflammation and *Cutibacterium acnes* proliferation characteristic of acne. In the Indian context, it is a second-line topical agent for moderate inflammatory acne, often used when first-line treatments like benzoyl peroxide or topical retinoids are insufficient or not tolerated.
Adult: Apply a thin layer to the affected area(s) twice daily, morning and evening.
Note: Clean and pat dry the affected skin area before application. Apply a pea-sized amount for the entire face or equivalent for other areas. Rub in gently and completely. Wash hands after application. Avoid contact with eyes, lips, mucous membranes, and broken skin. Do not occlude the area. If excessive dryness or peeling occurs, frequency may be reduced to once daily.
Dapsone's primary mechanism in acne is two-fold: 1) Anti-inflammatory: It inhibits the myeloperoxidase-H2O2-halide system in neutrophils, thereby suppressing the respiratory burst and generation of hypochlorous acid and other reactive oxygen species that contribute to tissue inflammation. It also inhibits neutrophil chemotaxis and the release of inflammatory cytokines (e.g., IL-8). 2) Antimicrobial: It exhibits bacteriostatic activity against *Cutibacterium acnes* by competitive antagonism of para-aminobenzoic acid (PABA), disrupting bacterial folate synthesis.
Pregnancy: Category C (US FDA). Animal studies have shown risk, but no adequate, well-controlled studies in pregnant women. Use only if potential benefit justifies potential risk to the fetus. Systemic absorption is minimal.
Driving: No effect expected.
| Topical Benzoyl Peroxide | Transient, localized orange or yellow discoloration of skin and hair upon simultaneous application. | Moderate |
| Oral Dapsone | Potential additive risk of systemic adverse effects (hemolysis, methemoglobinemia). | Major |
| Other Topical Acne Medications (Retinoids, Salicylic Acid) | May increase local skin irritation, dryness, and peeling. | Moderate |
| Trimethoprim-Sulfamethoxazole (Co-trimoxazole) | If used concurrently systemically, may increase risk of hemolytic anemia. | Major |