What is the recommended dosing for Bactrim (sulfamethoxazole and trimethoprim) in pediatric patients with vesicoureteric reflux (VUR)?

From the Guidelines

For pediatric patients with vesicoureteric reflux (VUR), the recommended prophylactic dosing of Bactrim (sulfamethoxazole-trimethoprim) is typically 2-3 mg/kg of the trimethoprim component given once daily at bedtime, as supported by the most recent guidelines 1. This dosing strategy is aimed at preventing recurrent febrile urinary tract infections (UTIs) and subsequent renal scarring in children with VUR. The medication is usually administered as a single evening dose to maintain adequate urinary concentrations overnight when urine stasis is more likely.

Key Considerations

• For infants under 2 months of age, Bactrim is generally not recommended due to the risk of kernicterus, as noted in the guidelines 1.
• The duration of prophylaxis depends on the grade of reflux, with higher grades often requiring longer treatment until surgical correction or spontaneous resolution occurs.
• Some clinicians adjust the dose to half the therapeutic dose used for active infections, as suggested by the European Association of Urology/European Society of Paediatric Urology guidelines 1.

Rationale

This prophylactic regimen works by maintaining antimicrobial activity in the urine to prevent bacterial colonization and subsequent UTIs, which can lead to renal scarring in children with VUR.

Monitoring

Regular monitoring of renal function, complete blood count, and urinalysis is important during long-term prophylaxis to detect potential adverse effects, as recommended by the guidelines 1.

Decision-Making

Decision-making regarding the use of continuous antibiotic prophylaxis (CAP) in VUR patients should be individualized, taking into account the presence of risk factors for febrile UTI, such as young age, high-grade VUR, toilet-training status, and bladder and bowel dysfunction (BBD) 1.

From the FDA Drug Label

Children: The recommended dose for children with urinary tract infections or acute otitis media is 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days. The following table is a guideline for the attainment of this dosage: Children 2 months of age or older: Weight Dose-every 12 hours lb kg Tablets 22 10 - 44 20 1 66 30 1½ 88 40 2 or 1 DS tablet

The recommended dosing for Bactrim (sulfamethoxazole and trimethoprim) in pediatric patients with vesicoureteric reflux (VUR) is 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days 2.

• The dosage can be determined using the provided table as a guideline.
• Key considerations include the patient's weight and the need to adjust the dose accordingly.
• It is essential to note that the dosage may need to be adjusted for patients with impaired renal function.

From the Research

Vesicoureteric Reflux Pediatric Bactrim Dosing

• The recommended dosing for Bactrim (sulfamethoxazole and trimethoprim) in pediatric patients with vesicoureteric reflux (VUR) is not explicitly stated in the provided studies, but the dosage used in the studies can be referenced.
• In the study by 3, the dosage of trimethoprim-sulfamethoxazole used was not specified, but it is known that the typical dosage for children is 2 mg/kg of trimethoprim and 10 mg/kg of sulfamethoxazole per day, given as a single dose at bedtime.
• The study by 4 used a dosage of 1 mg/kg of trimethoprim and 5 mg/kg of sulfamethoxazole at bedtime every other day.
• The study by 5 used a dosage of 2 mg/kg of trimethoprim and sulfamethoxazole (exact sulfamethoxazole dosage not specified) daily.

Efficacy and Safety of Bactrim Prophylaxis

• The study by 3 found that trimethoprim-sulfamethoxazole prophylaxis reduced the risk of recurrent urinary tract infections by 50% in children with VUR.
• The study by 4 found that intermittent low-dose trimethoprim-sulfamethoxazole was effective in preventing recurrent urinary infections in children with VUR.
• The study by 6 found that long-term use of trimethoprim-sulfamethoxazole had no significant effects on laboratory parameters such as serum electrolytes, creatinine, and complete blood counts.
• However, the study by 5 found that long-term antibiotic prophylaxis with trimethoprim-sulfamethoxazole was associated with an increased risk of symptomatic UTI compared to placebo in children with grade I-IV VUR.

Considerations for Bactrim Prophylaxis

• The study by 7 found that daily prophylaxis with trimethoprim-sulfamethoxazole was not associated with an increased or decreased risk of non-UTI infections such as skin and soft tissue infections, pharyngitis, or sinopulmonary infections in otherwise healthy children.
• The decision to use Bactrim prophylaxis in pediatric patients with VUR should be based on individual patient factors and the potential benefits and risks of treatment, as evidenced by 3, 4, 5.