Ceftriaxone IM Dosing for a 58-lb (26-kg) Child
For a 58-lb (26-kg) child, administer ceftriaxone 50 mg/kg IM once daily (1,300 mg) for most serious infections, or 75 mg/kg IM once daily (1,950 mg) for severe infections, not to exceed 2 grams daily for non-meningeal infections. 1
Weight-Based Dosing Algorithm
Standard dosing for children beyond the neonatal period:
For moderate infections (skin/soft tissue, uncomplicated pneumonia, UTI): 50 mg/kg once daily = approximately 1,300 mg for this 26-kg child 1, 2
For severe infections (complicated pneumonia, sepsis, osteomyelitis): 50–75 mg/kg once daily = 1,300–1,950 mg for this child 1, 2, 3
For bacterial meningitis: 100 mg/kg/day (divided every 12 hours or once daily) = 2,600 mg/day, but the maximum is 4 grams daily 1, 2
Maximum daily dose for non-meningeal infections is 2 grams, regardless of weight-based calculation 1, 2
Indication-Specific Guidance
Uncomplicated Gonococcal Infection
- Children weighing <45 kg receive 125 mg IM as a single dose 4, 2
- This 26-kg child falls below the 45-kg threshold and should receive the pediatric single-dose regimen 4
Gonococcal Bacteremia, Arthritis, or Disseminated Infection
- 50 mg/kg IM or IV once daily for 7 days (maximum 1 gram) = 1,300 mg daily for this child 2, 4
- Extend to 10–14 days if meningitis is documented 4, 2
Community-Acquired Pneumonia or Serious Bacterial Infections
- 50–75 mg/kg once daily is appropriate for hospitalized children 2, 3, 5
- For this 26-kg child: 1,300–1,950 mg once daily 2, 3
- Higher end of dosing range (75 mg/kg) is preferred for severe pneumonia, documented resistant organisms, or critically ill patients 2, 6
Acute Otitis Media
- Single IM dose of 50 mg/kg (not to exceed 1 gram) = 1,300 mg for this child 1
Practical Administration Considerations
IM injection should be administered deep into a large muscle mass (e.g., vastus lateralis, ventrogluteal) 1, 2
Counsel families that IM injection is painful; aspiration before injection helps avoid inadvertent intravascular administration 1, 2
Reconstitution for IM use: Mix with sterile water, 0.9% sodium chloride, or 5% dextrose to achieve concentrations of 250 mg/mL or 350 mg/mL 1
For a 1,300-mg dose at 350 mg/mL concentration, withdraw 3.7 mL of reconstituted solution 1
For a 1,950-mg dose (if using 75 mg/kg), consider splitting into two injection sites if volume exceeds 4 mL 1
Common Pitfalls to Avoid
Do not underdose severe infections: Always use the higher end of the dosing range (75 mg/kg) for life-threatening infections, empyema, or documented resistant pneumococcus 2, 3
Do not exceed 2 grams daily for non-meningeal infections, even if weight-based calculation suggests a higher dose 1, 2
Do not use ceftriaxone in neonates ≤28 days receiving calcium-containing IV solutions due to precipitation risk 1
Do not assume all infections require parenteral therapy: Oral amoxicillin is preferred for uncomplicated community-acquired pneumonia unless the child cannot tolerate oral therapy 3
For gonococcal infections, always add antichlamydial coverage (e.g., azithromycin) if Chlamydia trachomatis has not been ruled out 4, 1
Evidence Quality
The FDA-approved dosing for pediatric patients is 50–75 mg/kg/day for serious infections and 100 mg/kg/day for meningitis, with a maximum of 2 grams daily for non-meningeal infections 1. This is supported by multiple guidelines from the CDC 4, 2, American Academy of Pediatrics 4, 2, 3, and clinical studies demonstrating efficacy and safety of once-daily dosing in children 5, 7, 8. Pharmacokinetic modeling confirms that 50 mg/kg once daily provides adequate exposure for susceptible pathogens in most critically ill children, with 50 mg/kg twice daily reserved for patients with elevated glomerular filtration rates or less-susceptible organisms 6.