Components of Sulfatrim Pediatric
Sulfatrim pediatric contains two active ingredients: sulfamethoxazole and trimethoprim in a fixed combination ratio of 5:1 (sulfamethoxazole to trimethoprim). 1
Active Components
- Sulfamethoxazole: A sulfonamide antibiotic that inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA) 1
- Trimethoprim: A synthetic antibiotic that blocks the production of tetrahydrofolic acid from dihydrofolic acid by binding to and inhibiting the enzyme dihydrofolate reductase 1
These two medications work synergistically by blocking two consecutive steps in the bacterial folate synthesis pathway, which is essential for bacterial nucleic acid and protein production 1.
Dosage Forms
Sulfatrim pediatric is available in the following forms:
- Oral suspension: Typically contains 200 mg sulfamethoxazole and 40 mg trimethoprim per 5 mL 2
- Tablets: Available in pediatric formulations with appropriate dosing for children 2
Dosing Information
The FDA-approved pediatric dosing for trimethoprim-sulfamethoxazole is based on the trimethoprim component:
- Standard dosage: 8-12 mg/kg/day of trimethoprim component (40-60 mg/kg/day of sulfamethoxazole) divided into 2 doses given every 12 hours 2
- For Pneumocystis jirovecii pneumonia (PCP) treatment: 15-20 mg/kg/day of trimethoprim component (75-100 mg/kg/day of sulfamethoxazole) divided into 3-4 doses 2
- For PCP prophylaxis: 150 mg trimethoprim with 750 mg sulfamethoxazole/m² body surface area, given 3 days per week 3, 2
Inactive Ingredients
The oral formulation typically contains:
- Magnesium stearate
- Povidone
- Pregelatinized starch
- Sodium starch glycolate 1
Clinical Applications in Pediatrics
Sulfatrim pediatric is commonly used for:
- Urinary tract infections: First-line treatment for uncomplicated UTIs 2
- Otitis media: Alternative to amoxicillin for treatment of ear infections 3, 2
- Pneumocystis jirovecii pneumonia: Both treatment and prophylaxis in immunocompromised children 3, 2
- Shigellosis and other gastrointestinal infections 2
Important Considerations
- Age restrictions: Contraindicated in infants younger than 2 months due to risk of kernicterus and immature drug metabolism 2
- Dosage adjustment: Required for patients with renal impairment 2, 4
- Monitoring: Regular monitoring of complete blood counts, renal function, and liver function is recommended during treatment 2
- Adverse effects: Most common are gastrointestinal symptoms and hypersensitivity reactions; rare but serious adverse effects include Stevens-Johnson syndrome, blood dyscrasias, and hepatic necrosis 2
Pharmacokinetics in Pediatric Patients
Studies have demonstrated that when properly dosed (8/40 mg/kg/day of trimethoprim/sulfamethoxazole divided every 12 hours), children from 2 months to 18 years achieve comparable steady-state plasma concentrations to adults receiving standard dosing 1.
The combination has good bioavailability with peak blood levels occurring 1-4 hours after oral administration. The mean serum half-lives of sulfamethoxazole and trimethoprim are approximately 10 and 8-10 hours, respectively 1.