What is the ideal dose of Ceftriaxone (Ceftriaxone) injection for a 12-year-old child weighing 31.3 kilograms?

Ceftriaxone Dosing for a 12-Year-Old Child Weighing 31.3 kg

For this 12-year-old child weighing 31.3 kg, the ideal dose of ceftriaxone depends on the infection severity: 50-75 mg/kg/day (1565-2348 mg/day) for most infections, or 100 mg/kg/day (3130 mg/day) for meningitis or severe infections, not to exceed 4 grams daily. 1, 2

Standard Dosing Algorithm by Infection Type

For Skin and Soft Tissue Infections

• Dose: 50-75 mg/kg/day given once daily or divided every 12 hours 1, 2
• For this 31.3 kg child: 1565-2348 mg/day (can give 1565 mg once daily, or 782-1174 mg every 12 hours)
• Maximum daily dose: 2 grams for skin infections 2

For Severe Infections (Pneumonia, Sepsis, Complicated Intra-abdominal Infections)

• Dose: 50-100 mg/kg/day given once daily or divided every 12-24 hours 1, 2
• For this 31.3 kg child: 1565-3130 mg/day (can give up to 3130 mg once daily, or 1565 mg every 12 hours)
• For severe sepsis specifically, use the higher dosing range of 80-100 mg/kg/day 1
• Maximum daily dose: 4 grams 2

For Meningitis

• Initial dose: 100 mg/kg (not to exceed 4 grams) 2
• For this 31.3 kg child: 3130 mg initially
• Maintenance: 100 mg/kg/day (3130 mg/day) given once daily or divided every 12 hours 1, 2
• Duration: 7-14 days typically 2
• Maximum daily dose: 4 grams 2

For Community-Acquired Pneumonia

• Dose: 50-100 mg/kg/day given once daily or divided every 12-24 hours 1
• For pneumococcal pneumonia with penicillin resistance: 100 mg/kg/day every 12-24 hours 1

Administration Guidelines

Route and Timing

• Intravenous administration should be given over 30 minutes 2
• Can be given intramuscularly, though this is painful and patients should be counseled accordingly 1
• Once-daily dosing is appropriate for most pediatric infections due to ceftriaxone's long half-life 3, 4

Concentration for IV Administration

• Recommended concentrations: 10-40 mg/mL 2
• Lower concentrations may be used if desired 2

Critical Contraindications and Warnings

Calcium-Containing Solutions

• Do not use diluents containing calcium (Ringer's solution, Hartmann's solution) as particulate formation can result 2
• This is particularly critical in neonates but applies to all age groups 2

Drug Incompatibilities

• Do not physically mix with vancomycin, amsacrine, aminoglycosides, or fluconazole 2
• If these drugs must be given, administer sequentially with thorough line flushing between administrations 2

Common Pitfalls to Avoid

• Do not use the lower end of the dosing range (50 mg/kg/day) for severe sepsis—use 80-100 mg/kg/day instead 1
• Do not exceed 4 grams daily regardless of weight-based calculation 1, 2
• Do not exceed 2 grams daily for skin and soft tissue infections 2
• For this specific 31.3 kg child, the weight-based calculation of 100 mg/kg/day (3130 mg) is well below the 4-gram maximum, so the full weight-based dose can be safely administered 2

Duration of Therapy

• Continue therapy for at least 2 days after signs and symptoms of infection have disappeared 2
• Usual duration: 4-14 days for most infections 2
• For Streptococcus pyogenes infections: minimum 10 days 2
• For meningitis: 7-14 days typically 2