Ceftriaxone IM Dosing for 7-Year-Old, 35 kg Child
For a 7-year-old child weighing 35 kg, administer ceftriaxone 50-75 mg/kg/day IM, which translates to 1,750-2,625 mg daily, given as a single daily dose or divided every 12 hours, not exceeding 2 grams per day for most infections. 1, 2
Standard Dosing by Indication
For Most Common Infections (Skin/Soft Tissue, UTI, Bacteremia)
- Dose: 50-75 mg/kg once daily IM 1, 2
- For this 35 kg child: 1,750-2,625 mg daily
- Maximum: 2 grams/day for non-meningitic infections 2
- Can be given as single daily dose or divided every 12 hours 1, 3
For Meningitis (if suspected or confirmed)
- Dose: 100 mg/kg/day (3,500 mg for this child) 1, 2
- Maximum: 4 grams/day 2
- Given once daily or divided every 12 hours 1, 3
- Duration: 7-14 days typically 2
For Acute Otitis Media (Single-Dose Treatment)
- Single IM dose: 50 mg/kg (1,750 mg for this child) 2, 4
- Maximum: 1 gram for single-dose regimen 2
- Note: Three-day regimen (50 mg/kg/day × 3 days) shows superior efficacy for penicillin-resistant S. pneumoniae compared to single dose 4
Practical Administration Guidelines
Reconstitution for IM Injection
- For 2-gram vial: Add 7.2 mL diluent to achieve 250 mg/mL concentration 2
- Alternative: Add 4.2 mL diluent for 350 mg/mL concentration 2
- Use sterile water, 0.9% sodium chloride, or 5% dextrose 2
- Inject deep into large muscle mass with aspiration to avoid vascular injection 2
Key Safety Considerations
- Do NOT use calcium-containing diluents (Ringer's, Hartmann's) due to precipitation risk 2
- No dose adjustment needed for renal or hepatic impairment in children 2
- Stable for 2 days at room temperature or 10 days refrigerated after reconstitution 2
Evidence-Based Dosing Rationale
The 50-75 mg/kg once-daily regimen is well-established across multiple guidelines and demonstrates excellent efficacy for most pediatric infections 1, 3. Research confirms that 50 mg/kg once daily provides adequate plasma concentrations exceeding MIC for most pathogens throughout the 24-hour dosing interval 5, 6.
For critically ill children or infections with less-susceptible organisms (MIC ≥0.5 mg/L), consider 50 mg/kg twice daily rather than once daily to improve target attainment 7. This divided dosing achieves >99% probability of adequate drug exposure versus 96.8% with once-daily dosing 7.
Common Pitfall to Avoid
The FDA label states maximum 2 grams/day for non-meningitic infections 2, which means for this 35 kg child, the calculated dose of 75 mg/kg (2,625 mg) would need to be capped at 2,000 mg unless treating meningitis. For severe infections requiring higher doses, use 100 mg/kg (up to 4 grams) only when meningitis is documented or strongly suspected 1, 2.