Dapsone is an antibiotic that works by inhibiting bacterial folate synthesis. It is clinically used to treat leprosy and pneumocystis pneumonia. Side effects include hemolysis in patients with G6PD deficiency, rare bone marrow failure or agranulocytosis, as well as induction of methemoglobinemia by way of oxidizing the iron in heme to its Fe3+ form.

Key Points

  • Dapsone
    • Mechanism
      • Inhibits bacterial folate synthesis
        • Via competitive antagonism of para-aminobenzoic acid (PABA)
        • Similar to sulfonamides, but structurally distinct agent
    • Clinical Use
      • M. leprae (leprosy)
      • Pneumocystis jiroveci prophylaxis and treatment
    • Adverse Effects
      • Hemolysis in G6PD
        • Dapsone is an oxidizing agent and can increase oxidative stress on RBCs
      • Methemoglobinemia
        • Dapsone is an oxidizing agent
        • Oxidizes Fe2+ (ferrous iron) in heme to Fe3+ (ferric iron)
      • Agranulocytosis