What is the recommended dose of ceftriaxone (Ceftriaxone) IV for a 5-year-old child weighing 16kg?

Ceftriaxone IV Dosing for a 5-Year-Old, 16kg Child

For this 5-year-old child weighing 16kg, administer ceftriaxone 50-75 mg/kg/day IV (800-1200 mg/day) for most serious infections, or 100 mg/kg/day (1600 mg/day) for meningitis or highly resistant pneumococcal infections, given either once daily or divided every 12 hours. 1, 2

Indication-Based Dosing Algorithm

For Community-Acquired Pneumonia or Most Serious Infections

• Standard dose: 50-75 mg/kg/day (800-1200 mg/day for this 16kg child) 1, 2
• Can be administered as a single daily dose or divided every 12 hours 3, 1
• Maximum daily dose should not exceed 2 grams for non-meningitis infections 2

For Suspected Penicillin-Resistant Pneumococcus (MIC ≥4.0 μg/mL)

• Higher dose: 100 mg/kg/day (1600 mg/day for this 16kg child) given every 12-24 hours 3, 4
• This dosing is specifically recommended by the Infectious Diseases Society of America for resistant strains 4

For Bacterial Meningitis

• Initial dose: 100 mg/kg (1600 mg as a single dose, not to exceed 4 grams) 2
• Maintenance: 100 mg/kg/day (1600 mg/day) divided every 12 hours or given once daily 3, 1, 2
• Infusion time: 30 minutes (60 minutes only required for neonates) 2

Once-Daily vs. Twice-Daily Dosing Considerations

Once-daily dosing is generally preferred for most indications based on recent pharmacokinetic evidence:

• A 2024 population pharmacokinetic study demonstrated that 100 mg/kg once daily achieves superior CSF penetration and earlier target attainment compared to 50 mg/kg twice daily for bacterial meningitis 5
• For meningitis with MIC 1 mg/L, once-daily dosing achieved 88% probability of target attainment at 24 hours versus only 53% for twice-daily dosing 5
• However, for critically ill children with augmented renal clearance (eGFR >80 mL/min/1.73 m²) or less-susceptible pathogens (MIC ≥0.5 mg/L), twice-daily dosing of 50 mg/kg may improve target attainment 6

Pathogen-Specific Guidance

For Streptococcus pneumoniae

• Penicillin-susceptible strains (MIC <2.0 μg/mL): 50-100 mg/kg/day every 12-24 hours 3, 4
• Penicillin-resistant strains (MIC ≥4.0 μg/mL): 100 mg/kg/day every 12-24 hours 3, 4

For Group A Streptococcus or Haemophilus influenzae

• 50-100 mg/kg/day every 12-24 hours 3, 4

Practical Dosing for This Patient

For a 16kg child:

• Standard infections: 800-1200 mg/day (50-75 mg/kg/day) 1, 2
• Severe pneumonia or resistant organisms: 1600 mg/day (100 mg/kg/day) 3, 1
• Meningitis: 1600 mg/day (100 mg/kg/day) 3, 1, 2

Administration Details

• Infusion time: 30 minutes for pediatric patients (this child is beyond the neonatal period) 2
• Concentration: 10-40 mg/mL recommended for IV administration 2
• Duration: Continue for at least 2 days after signs and symptoms resolve; typical duration 4-14 days depending on infection severity 2

Important Caveats

• Do not use calcium-containing diluents (Ringer's solution, Hartmann's solution) as particulate formation can occur 2
• Flush IV lines thoroughly if administering other antimicrobials sequentially, as vancomycin, aminoglycosides, and fluconazole are incompatible 2
• No renal dose adjustment needed unless there is severe combined renal and hepatic impairment 2
• The FDA label specifies that total daily dose should not exceed 2 grams for skin/soft tissue infections, but allows up to 4 grams daily for meningitis and serious infections 2