Sulfones Used in the Treatment of Leprosy
A number of drugs closely related to the sulfonamides (eg, dapsone)
have been used effectively in the long-term treatment of leprosy.
The clinical manifestations of both lepromatous and tuberculoid leprosy
can often be suppressed by treatment extending over several years.
At least 530% of Mycobacterium
leprae organisms are resistant to dapsone, so initial combined
treatment with rifampin is advocated. Dapsone, 100 mg daily, is
effective therapy for mild to moderate Pneumocystis pneumonia in AIDS
when combined with trimethoprim, 20 mg/kg/d in
four divided doses. At a dose of 50100 mg daily or 100
mg two or three times a week, it is effective prophylaxis for Pneumocystis jiroveci (formerly Pneumocystis carinii) infection and,
when combined with pyrimethamine, 50 mg per week, also prevents Toxoplasma encephalitis in HIV-infected
Absorption, Metabolism, & Excretion
All sulfones are well absorbed from the intestinal tract, are
distributed widely in all tissues, and tend to be retained in skin,
muscle, liver, and kidney. Leprous skin contains ten times more
drug than normal skin. Sulfones are excreted into the bile and reabsorbed
by the intestine, prolonging therapeutic blood levels. Excretion
into the urine is variable, and the drug occurs in urine mostly
as a glucuronic acid conjugate.
Dosages & Routes of Administration
See Leprosy, in Chapter 33: Bacterial & Chlamydial Infections, for recommendations.
The sulfones may cause any of the side effects listed above for sulfonamides. Considering that sulfones can be cross-reactive with sulfonamides, they should not be used in those patients experiencing significant sulfonamide adverse events. Anorexia, nausea, and vomiting are common. Hemolysis, methemoglobinemia, or agranulocytosis may occur. G6PD status should always be determined prior to initiation of dapsone therapy. If sulfones are not tolerated, clofazimine can be substituted.