What is the recommended dose of Septran (co-trimoxazole) for pediatric patients?

Septran (Co-trimoxazole) Dosing in Children

For most pediatric indications, the standard dose of Septran is 8 mg/kg trimethoprim + 40 mg/kg sulfamethoxazole per day, divided into two doses given every 12 hours. 1, 2

Standard Dosing by Indication

Urinary Tract Infections and Acute Otitis Media

• Dose: 40 mg/kg sulfamethoxazole + 8 mg/kg trimethoprim per 24 hours, divided every 12 hours 1, 2
• Duration: 10 days for UTI, 5 days for acute otitis media 1
• Weight-based tablet guide for children ≥2 months: 1
  • 10 kg (22 lbs): 1 tablet every 12 hours
  • 20 kg (44 lbs): 1 tablet every 12 hours
  • 30 kg (66 lbs): 1½ tablets every 12 hours
  • 40 kg (88 lbs): 2 tablets or 1 DS tablet every 12 hours

Shigellosis

• Dose: Identical to UTI dosing (40 mg/kg sulfamethoxazole + 8 mg/kg trimethoprim per day) 1
• Duration: 5 days 1

Pneumocystis Jirovecii Pneumonia (PCP)

• Treatment dose: 75-100 mg/kg/day sulfamethoxazole + 15-20 mg/kg/day trimethoprim, divided every 6 hours 1, 2, 3
• Duration: 14-21 days 1, 3
• Prophylaxis dose: 750 mg/m²/day sulfamethoxazole + 150 mg/m²/day trimethoprim, divided twice daily, given 3 consecutive days per week 1, 3
• Maximum daily dose should not exceed 1600 mg sulfamethoxazole and 320 mg trimethoprim 1

Critical Clinical Context

Current Position as Therapy

Septran is NO LONGER first-line therapy for childhood pneumonia. 4, 5 The WHO now strongly recommends amoxicillin (50 mg/kg in two divided doses for 5 days) as first-line treatment for non-severe pneumonia due to higher treatment failure rates and widespread bacterial resistance to co-trimoxazole. 4, 5 Co-trimoxazole may be considered an acceptable alternative only in specific circumstances. 4

When to Use Co-trimoxazole

• Acceptable indications: UTIs, acute otitis media (where resistance is not documented), shigellosis, and PCP treatment/prophylaxis 1, 5
• Avoid in pneumonia: Use amoxicillin first-line instead 4, 5

Important Dosing Considerations

Age Restrictions

• NOT recommended for children <2 months of age 1, 2

Renal Impairment Adjustments

• CrCl >30 mL/min: Standard dosing 1, 2
• CrCl 15-30 mL/min: 50% of usual dose 1, 2
• CrCl <15 mL/min: Not recommended 1, 2

Formulation Selection

• For children <20 kg, liquid formulation is recommended for more accurate dosing 3

Monitoring Requirements

Baseline and Follow-up Testing

• Obtain complete blood count with differential and platelet count at initiation 3
• Repeat monthly for prophylactic therapy to detect hematologic toxicity 3
• Approximately 15% of children experience substantial adverse reactions including rash, gastrointestinal disturbances, and hematologic abnormalities 3

Treatment Failure Assessment

• Reassess at 48-72 hours if no clinical improvement 5
• In HIV-endemic areas, reassess at 48 hours 5
• Treatment failure is defined as development of lower chest-wall indrawing, central cyanosis, stridor while calm, danger signs, or persistently raised respiratory rate at 72 hours 4

Critical Pitfalls to Avoid

Resistance Considerations

• Resistance to co-trimoxazole significantly impacts treatment outcomes in complicated UTIs and pneumonia 5
• Even in areas with documented resistance, co-trimoxazole may still be effective for PCP prophylaxis 6

Drug Interactions

• Concomitant use with methotrexate is NOT contraindicated despite common concerns 4
• NSAIDs or salicylates can be given concurrently with low-dose co-trimoxazole in children with normal renal function 4

Malaria-Endemic Regions

• In malaria-endemic areas, prescribe both first-line therapies for malaria and pneumonia concurrently if pneumonia cannot be distinguished from malaria 5
• Amoxicillin lacks anti-malarial activity, allowing concurrent malaria treatment, which supports its use as first-line therapy 5