Dapsone Dosing for Leucocytoclastic Vasculitis
For leucocytoclastic vasculitis, start dapsone at 100-150 mg daily, which has demonstrated prompt resolution of new lesion formation within 4-8 days in patients with chronic or recurrent disease. 1
Initial Dosing Strategy
- Begin with 100-200 mg daily for adult patients with chronic or recurrent leucocytoclastic vasculitis, as this dose range has shown effectiveness in multiple case reports and series 2, 1, 3
- For pediatric patients with IgA vasculitis (Henoch-Schönlein purpura), use 1-2 mg/kg once daily as the minimal effective dose 4
- The lower end of the dosing range (100 mg daily) minimizes hematologic adverse effects while maintaining therapeutic benefit 1
Expected Clinical Response Timeline
- New lesion formation typically stops within 4-8 days after reaching the therapeutic dose level 1
- Complete resolution of cutaneous lesions generally occurs within 1 week of initiating therapy at appropriate doses 3
- Rapid recurrence of lesions often occurs within 4-8 days after discontinuation or dose reduction below the critical therapeutic threshold, confirming drug efficacy 1
Critical Pre-Treatment Screening
- Screen all patients for G6PD deficiency before initiating dapsone, particularly males of African, Mediterranean, or Asian ancestry, as G6PD deficiency dramatically increases hemolysis risk even at doses below 50 mg daily 2
- Obtain baseline complete blood count, liver function tests, and renal parameters before starting therapy 2
Hematologic Monitoring Requirements
- Dose-related hemolysis and methemoglobinemia are the most common adverse effects, occurring primarily at doses of 200 mg or more per day 2
- Monitor complete blood counts regularly during treatment, as reversible anemia, methemoglobinemia, and neutropenia can develop 2
- Adverse effects rarely occur at doses less than 100 mg per day 2
Treatment Duration and Relapse Management
- Approximately 50% of patients relapse after treatment discontinuation, but these relapses respond well to reinitiation of therapy 4
- For chronic cutaneous manifestations lasting more than 6 weeks, continue dapsone for at least 1 week after complete resolution 4
- The duration of initial treatment does not significantly influence relapse rates, so base continuation on clinical response rather than arbitrary time periods 4
Important Clinical Caveats
- Dapsone is effective for cutaneous manifestations but does not improve renal involvement in IgA vasculitis 4
- Watch for dapsone hypersensitivity syndrome (fever, exfoliative dermatitis, hepatic dysfunction, methemoglobinemia) beginning 1-4 weeks into therapy 2
- Consider colchicine as an alternative if dapsone is contraindicated or not tolerated 5
- For severe cases with hemorrhagic blisters suggesting incipient skin necrosis, corticosteroids may be indicated in addition to or instead of dapsone 5