Dosing and uses of Dapsone
Adult dosage forms and strengths
tablet
- 25mg
- 100mg
Dermatitis Herpetiformis
50 mg PO qDay, titrate to 300 mg qDay or higher to achieve desired effect
Reduce dose to minimum effective dose within the range of 50-300 mg qDay as soon as possible
Leprosy
100 mg PO qDay, in combination with other antileprosy drugs
Tuberculoid or Lepromatous Disease
100 mg PO qDay with rifampin 600 mg PO qDay
Pneumocystis (Carinii) Jiroveci (Off-label)
Prophylaxis
- 100 mg PO qDay or divided BID as monotherapy, OR
- 50 mg qDay in combination with weekly pyrimethamine and leucovorin
Treatment
- 100 mg PO qDay in combination with trimethoprim for 21 days
Toxoplasmosis (Orphan)
Prophylaxis in severely immunocompromised patients (CD4 count <100)
Orphan indication sponsor
- Jacobus Pharmaceutical Company, Inc; 37 Cleveland Lane, P.O. Box 5290; Princeton, NJ 08540
Pediatric dosage forms and strengths
tablet
- 25mg
- 100mg
Leprosy
1-2 mg/kg PO qDay; not to exceed 100 mg/day in combination with other antileprosy agents
Dosing considerations
- Administer for 3 years (minimum) in combination with multidrug regimen (ie, rifampin)
Pneumocystis (Carinii) Jiroveci (Off-label)
Prophylaxis
- >1 month old: 2 mg/kg PO qDay; not to exceed 100 mg/day, OR
- 4 mg/kg/dose PO qWeek; not to exceed 200 mg/week
- Adolescents: 100 mg PO qDay or divided BID as monotherapy, OR 50 mg qDay in combination with weekly pyrimethamine and leucovorin
Treatment
- >1 month old: 2 mg/kg PO qDay in combination with trimethoprim for 21 days
- Adolescents: 100 mg PO qDay in combination with trimethoprim for 21 days
Dapsone adverse (side) effects
1-10%
Hemolysis
Methemoglobinemia
<1%
Reactional states (ie, abrupt changes in clinical activity occurring during any leprosy treatment; classified as reversal of erythema nodosum leprosum reactions)
Insomnia
Headache
Exfoliative dermatitis
Photosensitivity
Nausea
Vomiting
Anemia
Leukopenia
Agranulocytosis
Hepatitis
Cholestatic jaundice
Peripheral neuropathy (usually in nonleprosy patients)
Blurred vision
Tinnitus
SLe
Warnings
Contraindications
Hypersensitivity to drug or component
Cautions
May cause blood dyscrasias (eg, agranulocytosis); monitor closely
Peripheral neuropathy may occur
Toxic epidermal necrolysis and other dermatologic reactions may occur
Use caution when treating patients with hypersensitivity to sulfonamides
Bacterial and fungal superinfections may occur from prolonged treatments
Pregnancy and lactation
Pregnancy category: C
Lactation: Enters breast milk; not recommended (AAP Committee states "compatible with nursing")
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Dapsone
Mechanism of action
Sulfone; prevents normal bacterial utilization of para-aminobenzoic acid (PABA) for the synthesis of folic acid by acting as a competitive antagonist of PABA; it is bactericidal and bacteriostatic against Mycobacterium leprae
Absorption
Well absorbed
Peak plasma time: 4-8 hr (after ingestion)
Distribution
Protein bound: 70-90% (dapsone); 99% (metabolite)
Vd: 1.5 L/kg; throughout total body water and present in all tissues, especially liver and kidney
Metabolism
Hepatic P450 enzymes CYP2E1, CYP3A4
Elimination
Half-life: 28 hr
Excretion: Urine (85%) as metabolites
