Dapsone
(DDS, Diphenylsulfone)
Dapsone (Avlosulfon)
DDS (Avlosulfon)
Diphenylsulfone (Avlosulfon)
Dapsone
( DAP-sohn)
Pregnancy Category: C Avlosulfon (Rx)

Classification: Sulfone, leprostatic

Action/Kinetics: Has both bacteriostatic and bactericidal activity, especially against Mycobacterium leprae (Hansen's bacillus). Thought to interfere with the metabolism of the infectious organism. Widely distributed throughout the body. Peak plasma levels: 4-8 hr. Doses of 200 mg/day for 8 days will lead to a plateau plasma level of 0.1-7 mcg/mL. From 70% to 90% is bound to plasma proteins. t 1/2: About 28 hr. Acetylated in the liver and metabolites excreted in the urine. However, excretion is slow and constant blood levels can be maintained with usual dosage.

Uses: Lepromatous and tuberculoid types of leprosy, dermatitis herpetiformis. Investigational: Relapsing polychondritis, prophylaxis of malaria, inflammatory bowel disease, leishmaniasis, Pneumocystis carinii pneumonia, rheumatoid arthritis, lupus erythematosus, bites of the brown recluse spider.

Contraindications: Advanced amyloidosis of kidneys. Lactation.

Side Effects: Hematologic: Hemolytic anemia, agranulocytosis methemoglobinemia. GI: N&V;, anorexia, abdominal discomfort. CNS: Headache, insomnia, vertigo, paresthesia, psychoses, peripheral neuropathy. Dermatologic: Photosensitivity, lupus-like syndrome. Hypersensitivity: Severe skin reactions including exfoliative dermatitis, erythema multiforme, toxic erythema, urticaria, erythema nodosum, toxic erythema, toxic epidermal necrolysis, morbilliform and scarlatiniform reactions. Sulfone syndrome: Potentially fatal hypersensitivity reaction, including symptoms of fever, malaise, jaundice with hepatic necrosis exfoliative dermatitis, lymphadenopathy, methemoglobinemia, and hemolytic anemia. Renal: Nephrotic syndrome, renal papillary necrosis, albuminuria. Miscellaneous: Muscle weakness, blurred vision, tinnitus, male infertility, fever, tachycardia, mononucleosis-type syndrome, pulmonary eosinophilia, pancreatitis.
A leprosy-reactional state may occur in large numbers of clients during therapy with dapsone. Type 1 occurs soon after therapy is initiated. Clients manifest an enhanced delayed hypersensitivity syndrome, leading to swelling of existing nerve and skin lesions with possible neuritis. However, this is not an indication to discontinue therapy. Steroids, analgesics, and surgical decompression of swollen nerve trunks may be used to reduce symptoms. Type 2 occurs in nearly 50% of clients during the first year of therapy. Symptoms include fever, erythematous skin nodules, joint swelling, neuritis, orchitis, malaise, depression, iritis, or epistaxis. Usually therapy is continued with the use of analgesics, steroids, or clofazimine to suppress the reaction.

Laboratory Test Alterations: Altered liver function tests.

Overdose Management: Symptoms: N&V;, hyperexcitability (up to 24 hr after ingestion of an overdose). Methemoglobin-induced depression, seizures severe cyanosis, headache, hemolysis. Treatment: Gastric lavage. In normal and methemoglobin-reductase deficient clients, give methylene blue, 1-2 mg/kg by slow IV (may need to be repeated if methemoglobin reaccumulates). In nonemergencies, methylene blue may be given PO, 3-5 mg/kg/4-6 hr.

Drug Interactions: Charcoal, activated / Absorption of dapsone from GI tract Didanosine / Possible therapeutic failure of dapsone infection Para-aminobenzoic acid / Effect of dapsone Probenecid / Effect of dapsone due to inhibition of renal excretion Pyrimethamine / Risk of hematologic reactions Rifampin / Effect of dapsone due to plasma clearance Trimethoprim / Serum levels of both drugs &aroowup; pharmacologic and toxic effects of both

How Supplied: Tablet: 25 mg, 100 mg

Dosage
?Tablets Leprosy.
Adults: 50-100 mg/day. Initiate and continue the full dose without interruption.
Leprosy, bacteriologically negative tuberculoid and indeterminate type.
Adults: 100 mg/day with rifampin, 600 mg/day for 6 months; then, continue for a minimum of 3 years.
Leprosy, lepromatous and borderline clients.
100 mg/day for at least 2 years with rifampin, 600 mg/day. A third antileprosy drug may be added such as clofazimine, 50-100 mg/day or ethionamide, 250-500 mg/day. Dapsone is continued for up to 10 years until skin scrapings and biopsies are negative for 1 year.
Dermatitis herpetiformis.
Adults, initial: 50 mg/day; dosage may be increased to 300 mg/day or higher, if necessary. Maintenance: Reduce dosage to minimum maintenance dose as soon as possible; maintenance dosage may be reduced or eliminated in clients on a gluten-free diet. Dosage is correspondingly less in children.