Bactrim Dosage for a 10-Year-Old Child Weighing 28kg
For a 10-year-old child weighing 28kg, the recommended dose of Bactrim (trimethoprim/sulfamethoxazole) is 8mg/kg/day of trimethoprim component and 40mg/kg/day of sulfamethoxazole component, divided into two doses every 12 hours. 1
Calculation of Exact Dosage
Based on the FDA-approved dosing guidelines:
- For a 28kg child:
- Trimethoprim component: 8mg/kg/day = 224mg/day
- Sulfamethoxazole component: 40mg/kg/day = 1120mg/day
- Divided into two doses = 112mg trimethoprim and 560mg sulfamethoxazole every 12 hours
Practical Administration
The WHO Pocket Book of Hospital Care for Children provides specific guidance for various conditions requiring Bactrim 2:
- For urinary tract infections: 10mg/kg trimethoprim plus 40mg/kg sulfamethoxazole twice daily for 5 days
- For acute otitis media: 4mg/kg trimethoprim plus 20mg/kg sulfamethoxazole twice daily for 5 days
For a 28kg child, this would translate to:
- UTI treatment: 280mg trimethoprim and 1120mg sulfamethoxazole per day
- Otitis media: 224mg trimethoprim and 1120mg sulfamethoxazole per day
Dosage Forms and Administration
Bactrim is available in:
- Regular strength tablets (80mg trimethoprim/400mg sulfamethoxazole)
- Double strength tablets (160mg trimethoprim/800mg sulfamethoxazole)
- Pediatric suspension (40mg trimethoprim/200mg sulfamethoxazole per 5mL)
For a 28kg child, the most appropriate form would be the pediatric suspension, with approximately 14mL per dose twice daily for standard dosing.
Important Considerations
- Duration of therapy: Typically 5-10 days depending on the indication 1
- Contraindications: Bactrim is contraindicated in children under 2 months of age 1
- Monitoring: Complete blood counts should be monitored, especially for prolonged therapy 3
- Renal function: Dosage adjustment is required for impaired renal function 1
Special Populations
For HIV-infected children requiring Pneumocystis jiroveci pneumonia prophylaxis, the CDC recommends a different dosing regimen of 150mg/m² trimethoprim and 750mg/m² sulfamethoxazole daily 2.
Potential Side Effects
Common side effects include:
- Gastrointestinal disturbances
- Hypersensitivity skin reactions
- Rarely: blood dyscrasias, Stevens-Johnson syndrome
Clinical Pearls
- Always calculate the dose based on the trimethoprim component
- For severe infections, higher doses may be required (up to 20mg/kg/day trimethoprim component)
- Ensure adequate hydration during treatment to prevent crystalluria
- Consider local antimicrobial resistance patterns when prescribing for empiric therapy
By following these dosing guidelines, you can ensure appropriate antimicrobial coverage while minimizing the risk of adverse effects in pediatric patients.