Dapsone

Dermatitis herpetiformis: (D.H.) Leprosy: All forms of leprosy except for cases of proven Dapsone resistance.

CONTRAINDICATION Hypersensitivity to Dapsone and/or its derivatives.

The patient should be warned to respond to the presence of clinical signs such as sore throat, fever, pallor, purpura or jaundice. Deaths associated with the administration of Dapsone have been reported from agranulocytosis, aplastic anemia and other blood dyscrasias. Complete blood counts should be done frequently in patients receiving Dapsone. The FDA Dermatology Advisory Committee recommended that, when feasible, counts should be done weekly for the first month, monthly for six months and semi-annually thereafter.

If a significant reduction in leucocytes, platelets or hemopoiesis is noted, Dapsone should be discontinued and the patient followed intensively. Folic acid antagonists have similar effects and may increase the incidence of hematologic reactions; if co-administered with Dapsone the patient should be monitored more frequently. Patients on weekly pyrimethamine and Dapsone have developed agranulocytosis during the second and third month of therapy.

Severe anemia should be treated prior to initiation of therapy and hemoglobin monitored. Hemolysis and methemoglobin may be poorly tolerated by patients with severe cardiopulmonary disease. Cutaneous reactions, especially bullous, include exfoliative dermatitis and are probably one of the most serious, though rare, complications of sulfone therapy. They are directly due to drug sensitization. Such reactions include toxic erythema, erythema multiforme, toxic epidermal necrolysis, morbilliform and scarlatiniform reactions, urticaria and erythema nodosum.

If new or toxic dermatologic reactions occur, sulfone therapy must be promptly discontinued and appropriate therapy instituted. Leprosy reactional states, including cutaneous, are not hypersensitivity reactions to Dapsone and do not require discontinuation. See special section.

In addition to the warnings listed above, the following syndromes and serious reactions have been reported in patients on Dapsone. Hematologic Effects: Dose-related hemolysis is the most common adverse effect and is seen in patients with or without G6PD deficiency. Almost all patients demonstrate the inter-related changes of a loss of 1g to 2g of hemoglobin, an increase in the reticulocytes (2% to 12%), a shortened red cell life span and a rise in methemoglobin.