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sulfamethoxypyridazine

J01ED05

Forms & Strengths

Oral tablets 500 mg

Adult Dosing

Initial dose: 1 to 2 g on the first day
Maintenance dose: 500 mg to 1 g daily, administered as a single daily dose

Pediatric Dosing

Not recommended for routine use in infants under 2 months of age due to risk of kernicterus
Pediatric maintenance: 25 to 30 mg/kg on the first day, followed by 12.5 to 15 mg/kg daily thereafter

Indications

Treatment of susceptible bacterial infections (historically used for urinary tract infections and respiratory infections)
Note: Largely withdrawn or restricted from global markets due to severe adverse skin reactions and availability of safer alternatives

Mechanism of Action

Competitive inhibitor of bacterial enzyme dihydropteroate synthase
Blocks bacterial synthesis of dihydrofolic acid, inhibiting nucleic acid synthesis and bacterial growth (bacteriostatic)

Contraindications

Known hypersensitivity to sulfonamides
Infants under 2 months of age (risk of kernicterus)
Pregnant women at term and nursing mothers
Severe hepatic impairment or hepatic damage
Severe renal insufficiency

Adverse Reactions

Severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome and toxic epidermal necrolysis
Hematologic toxicities: agranulocytosis, aplastic anemia, hemolytic anemia, leukopenia, thrombocytopenia
Gastrointestinal: nausea, vomiting, diarrhea, hepatitis, pancreatitis
Hypersensitivity: drug rash with eosinophilia and systemic symptoms (DRESS), serum sickness-like reactions
Renal: crystalluria, hematuria, interstitial nephritis

Drug Interactions

Potentiation of oral anticoagulants (e.g., warfarin), increasing bleeding risk
Enhanced hypoglycemic effect of sulfonylureas
Increased plasma concentrations and toxicity of methotrexate
Decreased efficacy of concurrent bacteriostatic antibiotics
Increased risk of crystalluria and nephrotoxicity with methenamine

Curated Content: Needs Vetting Before Put to Clinical Use