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Dapsone-mediated agranulocytosis: risks, possible mechanisms and prevention
1Mechanisms of Drug Toxicity Group, Pharmaceutical Sciences Institute, Aston University, Aston Triangle, Birmingham, B4 7ET, UK. m.d.coleman@aston.ac.uk
Toxicology
|April 20, 2001
Summary
Agranulocytosis, a severe reaction to medications like dapsone, can be life-threatening. The risk is significantly higher in patients with dermatitis herpetiformis, necessitating careful monitoring.
Area of Science:
- Pharmacology
- Hematology
- Dermatology
Background:
- Agranulocytosis is a rare, severe, and unpredictable idiosyncratic drug reaction.
- It presents as fever and infection, with neutrophil counts below 0.5x10^9/L, typically 1-3 months after drug initiation.
- Commonly associated drugs include aminopyrine, dipyrone, clozapine, anti-thyroid agents, sulphonamides, and dapsone.
Purpose of the Study:
- To investigate the varying risks of agranulocytosis associated with dapsone therapy.
- To compare the incidence of agranulocytosis in different patient populations and conditions.
Main Methods:
- Review of documented cases and incidence rates of agranulocytosis linked to specific drugs.
- Comparative analysis of agranulocytosis risk in leprosy patients, malaria patients on dapsone/maloprim, and dermatitis herpetiformis (DH) patients.
Main Results:
- Dapsone use in leprosy patients has a near-zero risk of agranulocytosis.
- Oral dapsone for malaria carries a risk of 1 in 10,000-20,000.
- Dapsone use in DH patients increases agranulocytosis risk 25-33 fold, potentially due to high plasma levels or immune response.
Conclusions:
- Dapsone poses a significantly elevated risk for agranulocytosis in dermatitis herpetiformis patients.
- Monitoring neutrophil counts during the first 3 months of dapsone therapy is crucial for DH patients.
- Topical dapsone for acne in young patients has a very low risk of agranulocytosis.