Ceftriaxone Dosing for a 21 kg Child
For a child weighing 21 kg, the recommended dose of ceftriaxone is 50-75 mg/kg/day, which equals 1050-1575 mg per day, administered once daily or divided every 12-24 hours depending on the severity of infection. 1, 2
General Dosing Guidelines
- For less severe infections, administer 50-75 mg/kg/day (1050-1575 mg for a 21 kg child) given once daily or divided every 12-24 hours 1
- For severe infections including pneumonia, administer 50-100 mg/kg/day (1050-2100 mg for a 21 kg child) given once daily or divided every 12-24 hours 1
- The total daily dose should not exceed 2 grams for most infections in pediatric patients 2
- For bacterial meningitis, administer 100 mg/kg/day (2100 mg for a 21 kg child) divided every 12-24 hours, with a maximum of 4 g daily 1, 2
Indication-Specific Dosing
Skin and Skin Structure Infections
- 50-75 mg/kg/day (1050-1575 mg for a 21 kg child) given once daily or in equally divided doses twice a day 2
- Total daily dose should not exceed 2 grams 2
Acute Otitis Media
- Single intramuscular dose of 50 mg/kg (1050 mg for a 21 kg child), not to exceed 1 gram 2
Serious Infections (Other than Meningitis)
- 50-75 mg/kg/day (1050-1575 mg for a 21 kg child) divided every 12 hours 2
- Total daily dose should not exceed 2 grams 2
Meningitis
- Initial therapeutic dose of 100 mg/kg (2100 mg for a 21 kg child), not to exceed 4 grams 2
- Maintenance dose of 100 mg/kg/day (2100 mg for a 21 kg child), not to exceed 4 grams daily 2
- May be administered once daily or in equally divided doses every 12 hours 2
- Usual duration of therapy is 7-14 days 2
Pathogen-Specific Considerations
- For Streptococcus pneumoniae with penicillin MIC <2.0 μg/mL: 50-100 mg/kg/day every 12-24 hours 3
- For penicillin-resistant Streptococcus pneumoniae (MIC ≥4.0 μg/mL): 100 mg/kg/day every 12-24 hours 3
- For Haemophilus influenzae (β-lactamase producing): 50-100 mg/kg/day every 12-24 hours 3
- For gram-negative enteric bacilli: 100 mg/kg/day divided every 12 hours or 80 mg/kg/day every 24 hours (up to 4 g daily) 4
Administration Considerations
- Intravenous administration should be given over a period of 30 minutes 2
- For intramuscular administration, inject well within the body of a relatively large muscle 2
- Reconstitute with appropriate diluent according to package instructions 2
- Do not use diluents containing calcium, such as Ringer's solution or Hartmann's solution 2
Clinical Evidence Supporting Once-Daily Dosing
- Studies have shown that once-daily administration of ceftriaxone (50-80 mg/kg) is effective for most serious bacterial infections in children with a clinical cure rate of 94% 5
- The long half-life of ceftriaxone (average 4.2 hours in pediatric patients) supports once-daily dosing for most indications 6
- For patients with estimated glomerular filtration rate >80 mL/min/1.73 m² or in areas with less-susceptible pathogens (MIC ≥0.5 mg/L), a twice-daily dosing regimen of 50 mg/kg may improve target attainment 7
Important Precautions
- Ceftriaxone is contraindicated in neonates (≤28 days) if they require calcium-containing IV solutions due to risk of precipitation 2
- Monitor for adverse effects, although they are generally mild and do not typically require discontinuation of therapy 5
- For infections caused by Streptococcus pyogenes, therapy should be continued for at least 10 days 2