What are the pediatric doses of ceftriaxone and aciclovir for a 15 kg baby?

Pediatric Dosing for Ceftriaxone and Aciclovir in a 15 kg Child

Ceftriaxone Dosing

For a 15 kg child, the recommended dose of ceftriaxone is 50-75 mg/kg/day, which equals 750-1125 mg once daily. 1

Ceftriaxone can be administered either intravenously (IV) or intramuscularly (IM) depending on the clinical situation:

• For most infections: 50 mg/kg/day as a single daily dose
• For more severe infections: 75 mg/kg/day as a single daily dose
• Maximum daily dose: generally not to exceed 2 grams

The long half-life of ceftriaxone (5.2-8.4 hours in infants) allows for once-daily dosing, which is a significant advantage in pediatric patients 2.

Administration Considerations:

• IV administration should be given over 30 minutes
• IM injections should be limited to 1 g per injection site
• Should not be used in hyperbilirubinemic neonates 1

Aciclovir (Acyclovir) Dosing

For a 15 kg child with suspected herpes virus infection, the recommended dose of aciclovir is 250-500 mg/m² or 10-20 mg/kg every 8 hours intravenously. 3

For a typical 15 kg child (approximately 0.6-0.65 m² body surface area):

• Standard dose: 150-300 mg every 8 hours (10-20 mg/kg)
• Duration of therapy depends on the type of infection:
  • Mucocutaneous HSV: 5-7 days
  • Encephalitis: 14-21 days
  • Disseminated disease: 14-21 days

Administration Considerations:

• Aciclovir IV should be administered by slow infusion over at least 1 hour to prevent renal tubular damage
• Maintain adequate hydration during treatment
• Monitor renal function, especially in neonates and young infants

Monitoring Recommendations

For Ceftriaxone:

• No routine drug level monitoring required
• Monitor for clinical response within 48-72 hours
• Watch for signs of biliary sludging with prolonged use
• Consider monitoring CBC, liver and renal function with prolonged therapy

For Aciclovir:

• Monitor renal function before and during therapy
• Ensure adequate hydration
• Adjust dose in case of renal impairment
• Monitor for neurological adverse effects (tremors, confusion)

Important Precautions

1. Ceftriaxone:

   • Do not mix or administer simultaneously with calcium-containing solutions
   • Watch for diarrhea (possible C. difficile infection)
   • Monitor for hypersensitivity reactions

2. Aciclovir:

   • Ensure proper dilution to prevent crystalluria
   • Slower infusion rate in patients with renal impairment
   • Monitor for neurotoxicity, especially with high doses or renal impairment

Clinical Pearls

• Ceftriaxone's once-daily dosing improves compliance and reduces nursing time 4
• Aciclovir should be started as early as possible in suspected herpes infections for optimal outcomes
• Both medications have excellent CNS penetration when needed for meningitis or encephalitis
• For most pediatric infections, ceftriaxone at 50 mg/kg/day is sufficient, with higher doses (75 mg/kg/day) reserved for meningitis or severe infections 5

Remember to adjust dosing based on clinical response and specific infection being treated.