Indications And Clinical Uses: Leprosy; dermatitis herpetiformis; actinomycotic mycetoma.
Contra-Indications: Sulfones are contraindicated in patients with advanced amyloidosis of the kidneys.
Precautions: Dapsone should be used with caution in patients with cardiac, pulmonary, hepatic or renal disease. Routine hematologic analysis should be carried out during long-term therapy with sulfones, because of the danger of hemolytic anemia. The hemolytic effect of sulfones may be exaggerated in glucose-6-phosphate dehydrogenase deficient individuals.
Drug Interactions: Rifampicin has been reported to increase the plasma clearance of dapsone, and probenecid has been reported to decrease excretion of dapsone. Administration of dapsone with chloroquine and/or primaquine may lead to an increase of methemoglobin levels in individuals predisposed to methemoglobinemia.
Pregnancy and Lactation: The sulfone drugs are generally contraindicated in pregnancy and therefore the use of dapsone during pregnancy should be avoided unless, in the judgment of the physician, potential benefit outweighs the risk. Dapsone in high doses has been reported to be carcinogenic in rats and mice, but negative in salmonella mutagenicity assays. The relevance of this finding to human exposure is unclear. Dapsone is excreted in breast milk in therapeutic amounts. Sulfones may cause hemolytic anemia in glucose-6-phosphate dehydrogenase deficient neonates.
Reaction States: Leprosy patients receiving effective chemotherapy may suffer episodes of acute or chronic inflammation. Generally, antileprosy chemotherapy should be continued unchanged but these reactions must be adequately treated since they may result in crippling deformity.
Nonlepromatous Lepra Reactions: Complications may include severe peripheral neuritis with accompanying cutaneous sensory loss and paralysis. In the management of acute neuritis corticosteroids may be considered.
Lepromatous Lepra Reactions: Complications may include neuritis, an increase in muscle weakness, lymphadenitis, iridocyclitis, orchitis and more rarely nephritis and large-joint arthritis. In the management of these reactions, corticosteroids, and clofazimine may be considered.
Adverse Reactions: Most adverse reactions are dose-related and uncommon at dosages up to 100 mg daily. They include anorexia, nausea, vomiting, headache, dizziness, tachycardia, nervousness, insomnia and skin disorders. Agranulocytosis, peripheral neuritis and psychosis have also been reported. Varying degrees of dose-related hemolysis and methemoglobinemia occur in most individuals given more than 200 mg daily. Dosages up to 100 mg daily are unlikely to cause hemolysis, but individuals with glucose-6-dehydrogenase deficiency may be affected by dosages above 50 mg daily. Rare reactions include the “dapsone syndrome” and hypoalbuminemia.
The “dapsone syndrome” is hypersensitivity reactions which develop rarely and tend to occur during the first 6 weeks of therapy. Symptoms may include fever, eosinophilia, mononucleosis, lymphadenopathy, leukopenia, jaundice with hepatitis, and exanthematous skin eruptions which may progress to exfoliative dermatitis, toxic epidermal necrolysis, or Stevens-Johnson syndrome. Although patients usually improve if dapsone is withdrawn fatalities have occurred. Fixed drug eruptions occur in dark-skinned people. Although agranulocytosis has been reported rarely for dapsone when used alone, reports have been more common when the drug has been used with other agents in the prophylaxis of malaria. Other miscellaneous reactions such as peripheral neuropathy, nephrotic syndrome and renal papillary necrosis have been reported.
Symptoms And Treatment Of Overdose: Symptoms and Treatment: In cases of severe overdosage the stomach should be emptied by aspiration and lavage. There is no specific antidote and therefore treatment should be symptomatic e.g., i.v. methylene blue 1 to 2 mg/kg body weight, i.v. ascorbic acid 0.5 to 1 g and oxygen for the methemoglobinemia plus general supportive measures. The repeated administration of activated charcoal has been reported to increase the elimination rate of dapsone and its metabolite following overdosage.
Dosage And Administration: Leprosy: Adults: The standard dose is 100 mg daily (1 to 2 mg/kg body weight).
Children: Dosage should be adjusted according to body weight.
The modern treatment of leprosy involves the use of multiple drug regimens to avoid the development of resistant strains. The World Health Organization has made the following recommendations for standard adult treatment regimens (with dosage adjustments according to body weight): Multibacillary leprosy: rifampicin: 600 mg once-monthly, supervised; dapsone: 100 mg daily, self-administered; clofazimine: 300 mg once-monthly, supervised and 50 mg daily, self-administered.
Paucibacillary Leprosy: rifampicin: 600 mg once a month for 6 months, supervised; dapsone: 100 mg daily for 6 months, self-administered.
Further information on treatment regimens is contained in “Chemotherapy of Leprosy for Control Programmes” W.H.O. Technical Report Series 675 (1982).
Dermatitis Herpetiformis: Adults: The usual maintenance dosage is 50 to 100 mg daily, but as little as 50 mg weekly may be adequate. Dosages of up to 300 mg daily may be considered, but efforts should be made to reduce this to the minimal maintenance dosage as soon as possible.
Actinomycotic Mycetoma: Adults: Published reports suggest that a dose of 100 mg should be given twice daily and continued for some months after the clinical symptoms have disappeared.
Availability And Storage: Each round, biconvex, white tablet, embossed Ayerst on one side with a score line on other side, contains: dapsone USP 100 mg. Nonmedicinal ingredients: calcium carbonate, cornstarch and magnesium stearate. Energy: 0.5 kJ (0.12 kcal). Alcohol-, gluten-, lactose-, parabens-, sugar-, sulfites- and tartrazine-free. Bottles of 100. Store at room temperature. Protect from light. (Shown in Product Recognition Section)
AVLOSULFON® Wyeth-Ayerst Dapsone Antibacterial Sulfone