What is the recommended intravenous (IV) ampicillin dose for a child weighing 9.9 kilograms (kg)?

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IV Ampicillin Dosing for a 9.9kg Child

For a child weighing 9.9kg, the recommended intravenous (IV) ampicillin dose is 100-200 mg/kg/day divided every 6 hours, which equals approximately 247.5-495 mg per dose given four times daily. 1, 2

Dosing Calculation

  • For a 9.9kg child, the appropriate IV ampicillin dosing is:
    • Standard dose: 100-200 mg/kg/day divided every 6 hours 2
    • For this child: 990-1980 mg/day total (9.9kg × 100-200 mg/kg/day) 1
    • Per dose (q6h): 247.5-495 mg per dose 1

Indications and Dose Adjustments

  • For standard infections: 100 mg/kg/day (lower end of range) is typically sufficient 1
  • For severe infections or bacterial meningitis: Higher doses of 150-200 mg/kg/day are recommended 1, 2
  • For bacterial meningitis specifically: 150-200 mg/kg/day divided every 3-4 hours may be used 1

Administration Considerations

  • IV ampicillin should be administered within one hour after preparation as potency decreases significantly after this period 1
  • For direct IV use: Add 5 mL sterile water for injection to the appropriate vial and administer slowly over 3-5 minutes 1
  • For IV infusion: Reconstitute as directed and dilute with appropriate IV solution (stability varies by diluent) 1

Important Clinical Considerations

  • Treatment should continue for a minimum of 48-72 hours beyond the time that the patient becomes asymptomatic 1
  • For Group A beta-hemolytic streptococcal infections, a minimum of 10 days treatment is recommended to prevent acute rheumatic fever or acute glomerulonephritis 1
  • Bacteriostatic Water for Injection should not be used as a diluent when ampicillin will be used in newborns 1

Monitoring and Safety

  • Monitor for signs of allergic reactions, which are common with ampicillin 1
  • For prolonged therapy, periodic assessment of renal, hepatic, and hematopoietic function is recommended 1
  • More rapid IV administration than recommended may result in convulsive seizures 1

Remember that the dosage should be adjusted based on the specific infection being treated and the clinical response of the patient.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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