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sulfadimethoxine

J01ED01

Forms & Strengths

Oral suspension: 250 mg/5 mL
Tablets: 500 mg
Veterinary formulations widely available

Adult Dosing

Initial dose: 1 to 2 g (2 to 4 tablets) orally on the first day
Maintenance dose: 500 mg to 1 g (1 to 2 tablets) orally once daily
Severe infections: Increase maintenance dose accordingly

Pediatric Dosing

Children > 2 months:
Initial dose: 25 to 50 mg/kg on the first day
Maintenance dose: 12.5 to 25 mg/kg orally once daily

Indications

Treatment of susceptible bacterial infections (predominantly respiratory, urinary, and soft tissue) historically
Primarily used in veterinary medicine currently for coccidiosis and shipping fever complex

Mechanism of Action

Sulfonamide antimicrobial that competitively inhibits bacterial synthesis of dihydrofolic acid
Blocks the enzyme dihydropteroate synthase, preventing folic acid production essential for bacterial purine and pyrimidine synthesis

Contraindications

Hypersensitivity to sulfonamides
Infants under 2 months of age (risk of kernicterus)
Pregnancy at term and nursing mothers (risk of kernicterus in neonates)
Severe hepatic damage or blood dyscrasias
Porphyria

Adverse Reactions

Hypersensitivity reactions: rash, urticaria, pruritus, Stevens-Johnson syndrome, toxic epidermal necrolysis
Hematologic: agranulocytosis, aplastic anemia, thrombocytopenia, leukopenia, hemolytic anemia
Gastrointestinal: nausea, vomiting, diarrhea, hepatitis, pancreatitis
Renal: crystalluria, hematuria, toxic nephrosis

Drug Interactions

Oral anticoagulants (warfarin): potentiates anticoagulant effect by displacement from plasma proteins
Oral hypoglycemics (sulfonylureas): enhanced hypoglycemic response
Methenamine: increases risk of crystalluria in acidic urine
Cyclosporine: may decrease plasma concentrations of cyclosporine

Curated Content: Needs Vetting Before Put to Clinical Use