Dapsone (diaminodiphenylsulphone, DDS) is a medication which has an antileprotic and antimalarial action. Dapsone is a primary treatment for Dermatitis herpetiformis. It is an antibacterial drug for susceptible cases of leprosy. It is a white, odorless crystalline powder, practically insoluble in water and insoluble in fixed and vegetable oils. Dapsone is used for the prevention and treatment of pneumocystis carinii pneumonia (PCP) and toxoplasmosis gondii. Dapsone is also sometimes used in combination with the drug pyrimethamine and chloroquine for the prevention of malaria in certain areas where there is a high risk of chloroquine resistant Plasmodium falciparum malaria.
Dapsone inhibits the synthesis of dihydrofolic acid by competing with para-aminobenzoate for the active site of dihydropteroate synthetase. This action is not completely understood, though it appears similar to the actions of other sulphones. The anti-inflammatory effects of dapsone seem to be related to the presence of a large number of neutrophils in the affected tissue. Dapsone interferes with neutrophil infiltration and also suppresses neutrophil adherence. For the prevention of PCP, dapsone is taken on its own or in a variety of combinations with other drugs such as trimethoprin (TMP), pyrimethamine (Daraprim) and leucovorin. For the treatment of PCP, dapsone is taken with TMP.
Dapsone is an antibiotic effective against the bacteria that causes leprosy. It is an effective treatment for dermatitis herpetiformis, although it is unknown how dapsone helps with this disease. Dapsone is also used to prevent Pneumocystis carinii pneumonia in people infected with the human immunodeficiency virus (HIV).