28 - 187 - DAPSONE Flashcards
Pregnancy category of dapsone
Category C
Mechanism of action of dapsone
It inhibits the synthesis of dihydrofolic acid by competing with para-aminobenzoic acid for the active site of dihydropteroate synthetase
FDA-approved formulation of dapsone in acne
U.S. Food and Drug Administration (FDA) approved a 7.5% dapsone gel for once-daily application
The mechanism of action of topical dapsone here is likely to result from its combined antiinflammatory and antimicrobial activities
Aside from acne, Topical dapsone has also been shown in a case report to be effective in the treatment of what condition?
leukocytoclastic vasculitis
Increase Blood Levels of Dapsone (Greater Chance of Adverse Events)
Probenecid
Trimethoprim
Reduces Blood Levels of Dapsone (Lowers Effectiveness)
Rifampicin
Block N-Hydroxylation of Dapsone (Lessening Side Effects)
Cimetidine
Omeprazole
Therapeutic Indications for Dapsone
Initial dose of dapsone
50-100 mg/day
Topical dapsone (5% gel) is FDA approved for acne vulgaris in adults and adolescents up to how many years old?
12 yrs
Topical dapsone, when applied together with benzoyl peroxide, may cause what adverse reaction?
yellow-orange discoloration of the skin; it is washable from skin but may stain clothing
commonest side effects of dapsone
dose-related hemolysis.
Adverse Effects of Dapsone
Symptoms usually occur with methemoglobin levels of how many percent
20-30%
This has been used intentionally to lower methemoglobin levels in dapsone-treated patients by 27% to 60%
Cimetidine, which blocks the hydroxylation of dapsone
dietary supplement with antioxidant properties, has also been shown in vitro to decrease methemoglobin formation,
Lipoic acid
Symptoms of dapsone hypersensitivity syndrome occur within how many weeks of drug initiation?
First 6 weeks
most frequent cause of death in patients with dapsone hypersensitivity syndrome
Hepatic coma
Triad of dapsone hypersensitivity syndrome
Fever
Rash
Hepatitis
It is the reactivation of what virus that is thought to cause the late flaring of rash, fever, and hepatitis characteristically seen in drug hypersensitivity syndrome
HHV6
Symptoms of agranulocytosis
fever, pharyngitis, dysphagia, and oral ulcerations.
Laboratory Monitoring of dapsone
Treatment options for dapsone overdose
- activated charcoal - will reduce drug levels by removing drug from the gut
- Methylene blue, 1% solution given 1 to 2 mg/kg slowly intravenously can be used to decrease the degree of methemoglobinemia. G6PD-deficient patients should not be given methylene blue because they may have insufficient NADPH, and unreduced methylene blue is its own direct hemolytic agent.
- Ascorbic acid 1000 mg intravenously every 12 hours
