Tablet, 25 mg, 100 mg

General information

Dapsone is a sulfone that remains of prime importance in the treatment of leprosy. It is also used in the treatment of certain bullous dermatoses and skin diseases with neutrophilic infiltrates. It may block the release of chemotactic factors from neutrophils and may act as an immunomodulator.

After absorption from the gastrointestinal tract, dapsone is distributed widely in body tissues and it is subsequently retained selectively in skin, muscle, liver and kidneys. It is partially acetylated or conjugated in the liver and ultimately excreted in the urine as metabolites. A dose of 100 mg produces a peak serum concentration of approximately 2 μg/ml, which declines with a half-life of 1-2 days.

Clinical information

Uses

Treatment of:

• paucibacillary and multibacillary leprosy in combination with other antileprosy drugs¹
• bullous pemphigoid
• actinomycetoma
• dermatitis herpetiformis
• vasculitis.

¹ For further information, see WHO model prescribing information: drugs used in mycobacterial diseases. Geneva, World Health Organization, 1991.

Dosage and administration

Adults: 100 mg daily increased, as necessary, up to 200 mg daily until signs of remission are apparent. Continuous maintenance therapy, which is required in some cases, should be administered at the lowest dosage which prevents recurrence (50-100 mg daily).

Children: 1.0-1.5 mg/kg daily.

Contraindications

• Hypersensitivity to sulfones.
• Severe anaemia.
• Glucose-6-phosphate dehydrogenase deficiency.

Precautions

Pre-existing untreated severe anaemia should be treated before dapsone therapy is started.

Dapsone can induce haemolysis of varying degree, particularly in patients with glucose-6-phosphate dehydrogenase deficiency, and dose-dependent methaemoglobinaemia may supervene during the second week of treatment. The clinical response and the blood count must therefore be closely monitored in susceptible patients during the first weeks of treatment.

Use in pregnancy

Safe use in pregnancy has not been established. Dapsone should be used in the treatment of dermatological disorders only when the need of the mother outweighs the potential risk to the fetus.

Adverse effects

Dapsone is generally well tolerated at recommended dosages, but symptoms of gastrointestinal irritation occasionally occur. Other, less common reactions include headache, nervousness and insomnia.

Blurred vision, paraesthesiae, reversible peripheral neuropathy, drug fever, skin rashes and psychoses have also been reported. Hepatitis, Herxheimer reactions and agranulocytosis may rarely occur.

Overdosage

Acute overdosage results in nausea, vomiting and hyperexcitability. Orally administered activated charcoal may enhance the elimination of dapsone.

Storage

Tablets should be kept in well-closed containers, protected from light.