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sulfadiazine

J01EC02

Forms & Strengths

Oral Tablet: 500 mg

Adult Dosing

Toxoplasmosis: 1 to 1.5 g orally every 6 hours in combination with pyrimethamine
Chancroid: 1 g orally every 6 hours for 7 to 14 days
Prevention of rheumatic fever recurrence: 1 g orally daily

Pediatric Dosing

Congenital toxoplasmosis (infants > 2 months): 100 mg/kg/day orally divided every 12 hours with pyrimethamine and leucovorin
Toxoplasmosis (children > 2 months): 25 to 50 mg/kg orally every 6 hours
Rheumatic fever prophylaxis (children > 30 kg): 1 g orally daily
Rheumatic fever prophylaxis (children <= 30 kg): 500 mg orally daily

Indications

Treatment of toxoplasmosis in conjunction with pyrimethamine
Prevention of rheumatic fever recurrences
Treatment of chancroid

Mechanism of Action

Synthetic sulfonamide that acts as a competitive inhibitor of dihydropteroate synthase
Blocks bacterial biosynthesis of folic acid (pteroylglutamic acid) required for purine and pyrimidine synthesis

Contraindications

Hypersensitivity to sulfonamides
Porphyria
Infants under 2 months of age due to risk of kernicterus
Severe hepatic impairment or renal insufficiency

Adverse Reactions

Nausea, vomiting, and diarrhea
Hypersensitivity reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, and rash
Hematologic toxicities including agranulocytosis, aplastic anemia, hemolytic anemia, and thrombocytopenia
Crystalluria, hematuria, and nephrotoxicity
Drug fever and hepatitis

Drug Interactions

Anticoagulants (warfarin): potentiates hypoprothrombinemic effect
Oral hypoglycemic agents (sulfonylureas): enhanced hypoglycemic response
Methenamine: increases risk of crystalluria in acidic urine
Cyclosporine: may decrease plasma concentration of cyclosporine
Methotrexate: displaced from protein binding sites, increasing toxicity risk

Curated Content: Needs Vetting Before Put to Clinical Use