GANTRISIN PEDIATRIC

Clinical safety rating: caution

Comprehensive clinical and safety monograph for GANTRISIN PEDIATRIC (GANTRISIN PEDIATRIC).

How it works

Sulfisoxazole is a competitive inhibitor of bacterial dihydropteroate synthase, preventing the incorporation of para-aminobenzoic acid (PABA) into dihydrofolate, thereby inhibiting bacterial folic acid synthesis.

What the body does with it

Metabolism	Sulfisoxazole is primarily metabolized via acetylation and glucuronidation in the liver; it can also undergo oxidation by cytochrome P450 enzymes. Approximately 70% of the drug is excreted renally as unchanged drug and metabolites.
Excretion	Primarily renal (70-100% as unchanged drug and acetylated metabolites) via glomerular filtration and tubular secretion; <10% fecal.
Half-life	Terminal elimination half-life is 6-12 hours (prolonged in renal impairment; up to 30 hours in patients with creatinine clearance <10 mL/min).
Protein binding	50-60% bound to albumin.
Volume of Distribution	0.2-0.3 L/kg; distributes into extracellular fluid, CSF (30-80% of plasma concentration with inflamed meninges), and tissues.
Bioavailability	Oral: ~70-100% (sulfisoxazole acetyl suspension yields equivalent systemic exposure to sulfisoxazole base).
Onset of Action	Oral: 1-4 hours (therapeutic concentration achieved within 12-24 hours for systemic infections).
Duration of Action	Approximately 12 hours (dosing interval: every 4-6 hours for systemic infections; prolonged in renal impairment).

Classification & Brands

Dosing & administration

2-4 g initially, then 4-6 g/day in 3-6 divided doses orally, depending on severity. Alternatively, for sulfisoxazole (the active moiety), typical adult dose is 500 mg to 1 g orally every 6 hours. IM use: 50 mg/kg initially, then 100 mg/kg/day in divided doses every 6-8 hours. IV use: Not recommended in pediatric formulation.

Dosage form	SUSPENSION
Renal impairment	CrCl >50 mL/min: no adjustment; CrCl 10-50 mL/min: administer every 12-24 hours; CrCl <10 mL/min: administer every 24-48 hours or avoid use due to risk of crystalluria. For hemodialysis: supplemental dose after dialysis.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: cautious use, dose reduction may be needed; Child-Pugh C: contraindicated or avoid use due to risk of hepatotoxicity.
Pediatric use	Children ≥2 months: initial dose 75 mg/kg, then 150 mg/kg/day orally divided every 4-6 hours, not to exceed 6 g/day. For sulfisoxazole: 70 mg/kg loading dose, then 150 mg/kg/day divided every 4-6 hours. Contraindicated in infants <2 months unless used for congenital toxoplasmosis.
Geriatric use	Use with caution due to age-related renal impairment. Start at lower end of dosing range; monitor renal function and adjust based on CrCl. Increased risk of crystalluria and hypersensitivity reactions; ensure adequate fluid intake.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for GANTRISIN PEDIATRIC (GANTRISIN PEDIATRIC).

Breastfeeding	Sulfisoxazole is excreted into breast milk. M/P ratio not established. Potential for kernicterus in jaundiced or G6PD-deficient infants; avoid breastfeeding during therapy. The American Academy of Pediatrics considers it compatible with caution in healthy full-term infants.
Teratogenic Risk	Sulfisoxazole (Gantrisin) is a sulfonamide antibiotic. First trimester: No evidence of teratogenicity in humans, but animal studies show cleft palate and skeletal anomalies at high doses. Second and third trimesters: Risk of kernicterus in neonates due to bilirubin displacement from albumin; avoid use near term.

Warnings & precautions

■ FDA Black Box Warning

Sulfonamides have been associated with severe hypersensitivity reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias. Fatalities have occurred. Discontinue if rash or other serious adverse reactions occur.

Side Effect Profile

Serious Effects

Absolute Contraindications

Hypersensitivity to sulfonamides; infants <2 months of age (except for congenital toxoplasmosis); pregnant women at term; nursing mothers; patients with porphyria; concurrent use with methenamine (risk of crystalluria).

Clinical Precautions

Precautions

Use with caution in patients with renal or hepatic impairment, G6PD deficiency (risk of hemolytic anemia), porphyria, or severe allergies; maintain adequate fluid intake to prevent crystalluria; monitor complete blood counts and urinalysis; avoid use in infants <2 months of age (except for congenital toxoplasmosis) due to risk of kernicterus.

Clinical Tips & Counseling

Drug interactions

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GANTRISIN PEDIATRIC

Clinical safety rating: caution

Comprehensive clinical and safety monograph for GANTRISIN PEDIATRIC (GANTRISIN PEDIATRIC).

How it works

What the body does with it

Metabolism	Sulfisoxazole is primarily metabolized via acetylation and glucuronidation in the liver; it can also undergo oxidation by cytochrome P450 enzymes. Approximately 70% of the drug is excreted renally as unchanged drug and metabolites.
Excretion	Primarily renal (70-100% as unchanged drug and acetylated metabolites) via glomerular filtration and tubular secretion; <10% fecal.
Half-life	Terminal elimination half-life is 6-12 hours (prolonged in renal impairment; up to 30 hours in patients with creatinine clearance <10 mL/min).
Protein binding	50-60% bound to albumin.
Volume of Distribution	0.2-0.3 L/kg; distributes into extracellular fluid, CSF (30-80% of plasma concentration with inflamed meninges), and tissues.
Bioavailability	Oral: ~70-100% (sulfisoxazole acetyl suspension yields equivalent systemic exposure to sulfisoxazole base).
Onset of Action	Oral: 1-4 hours (therapeutic concentration achieved within 12-24 hours for systemic infections).
Duration of Action	Approximately 12 hours (dosing interval: every 4-6 hours for systemic infections; prolonged in renal impairment).

Classification & Brands

Dosing & administration

Dosage form	SUSPENSION
Renal impairment	CrCl >50 mL/min: no adjustment; CrCl 10-50 mL/min: administer every 12-24 hours; CrCl <10 mL/min: administer every 24-48 hours or avoid use due to risk of crystalluria. For hemodialysis: supplemental dose after dialysis.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: cautious use, dose reduction may be needed; Child-Pugh C: contraindicated or avoid use due to risk of hepatotoxicity.
Pediatric use	Children ≥2 months: initial dose 75 mg/kg, then 150 mg/kg/day orally divided every 4-6 hours, not to exceed 6 g/day. For sulfisoxazole: 70 mg/kg loading dose, then 150 mg/kg/day divided every 4-6 hours. Contraindicated in infants <2 months unless used for congenital toxoplasmosis.
Geriatric use	Use with caution due to age-related renal impairment. Start at lower end of dosing range; monitor renal function and adjust based on CrCl. Increased risk of crystalluria and hypersensitivity reactions; ensure adequate fluid intake.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for GANTRISIN PEDIATRIC (GANTRISIN PEDIATRIC).

Breastfeeding	Sulfisoxazole is excreted into breast milk. M/P ratio not established. Potential for kernicterus in jaundiced or G6PD-deficient infants; avoid breastfeeding during therapy. The American Academy of Pediatrics considers it compatible with caution in healthy full-term infants.
Teratogenic Risk	Sulfisoxazole (Gantrisin) is a sulfonamide antibiotic. First trimester: No evidence of teratogenicity in humans, but animal studies show cleft palate and skeletal anomalies at high doses. Second and third trimesters: Risk of kernicterus in neonates due to bilirubin displacement from albumin; avoid use near term.