Dapsone

Generic name:

Dapsone

Drug class:

Sulfone antibiotic; dihydropteroate synthase inhibitor; anti-inflammatory agent

Dosage form:

• Oral tablets (25 mg, 50 mg, 100 mg)
• Oral suspension (5 mg/mL)
• Topical gel/cream (5%)

Root of administration:

• Oral
• Topical

Dose:

• Leprosy: 1–2 mg/kg once daily or 100 mg once daily, often in combination therapy
• Dermatitis herpetiformis: 50–300 mg/day divided doses
• Pneumocystis jirovecii pneumonia prophylaxis: 50–100 mg once daily
• Acne vulgaris (off-label): 25–50 mg once daily
• Malaria prophylaxis (in combination regimens): Varies by regimen; consult label

Mechanism of action:

Dapsone competitively inhibits dihydropteroate synthase, blocking folate synthesis in susceptible organisms; it also exerts anti-inflammatory effects by inhibiting neutrophil myeloperoxidase and reducing neutrophil chemotaxis.

Drug usage cases:

• Leprosy (Hansen’s disease)
• Dermatitis herpetiformis
• Pneumocystis jirovecii pneumonia prophylaxis
• Acne vulgaris (off-label)
• Malarial prophylaxis in combination regimens (off-label)
• Brown recluse spider bite envenomation (off-label)

Drug contra indications:

• Hypersensitivity to dapsone or other sulfonamides
• Severe anemia (including preexisting hemolytic anemia)
• Glucose-6-phosphate dehydrogenase (G6PD) deficiency
• Acute porphyria
• Severe hepatic impairment

Side effects:

• Hemolytic anemia
• Methemoglobinemia
• Dapsone hypersensitivity syndrome (fever, rash, lymphadenopathy, hepatic dysfunction)
• Agranulocytosis
• Pancytopenia
• Hepatotoxicity (hepatitis)
• Peripheral neuropathy
• Gastrointestinal upset (nausea, vomiting)
• Headache
• Insomnia
• Neurological symptoms (dizziness, psychosis)
• Rash, pruritus
• Stevens-Johnson syndrome/toxic epidermal necrolysis

Warnings:

• Monitor complete blood count periodically for hemolysis and agranulocytosis
• Screen for G6PD deficiency prior to initiation
• Risk of methemoglobinemia; monitor methemoglobin levels if suspected
• Dapsone hypersensitivity syndrome may be fatal; discontinue immediately if suspected
• Use caution in patients with cardiac or pulmonary disease
• Monitor liver and renal function during prolonged therapy
• Risk of severe cutaneous adverse reactions (e.g., SJS/TEN)
• May exacerbate neuropathy; monitor for peripheral neuropathy
• Use caution in elderly and debilitated patients

Use during pregnancy or breastfeeding:

Pregnancy: Animal studies have shown adverse fetal effects; no adequate human studies. Use only if potential benefit justifies risk. Monitor for hemolytic anemia in the mother and fetus.

Breastfeeding: Excreted in breast milk; may cause hemolytic anemia and methemoglobinemia in the infant. Advise mothers to discontinue breastfeeding or the drug.