What is the recommended dosage of Zofran (ondansetron) for a 26-month-old patient weighing 31 pounds?

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Ondansetron Dosing for a 26-Month-Old Child Weighing 31 Pounds

Recommended Dose

For this 26-month-old patient weighing 31 pounds (14.1 kg), administer ondansetron 0.15 mg/kg per dose, which equals approximately 2.1 mg per dose, with a maximum single dose of 16 mg. 1

Weight-Based Calculation

  • The standard pediatric dose is 0.15 mg/kg per dose for children in this age range 1
  • For a 31-pound (14.1 kg) child: 14.1 kg × 0.15 mg/kg = 2.1 mg per dose 1
  • This dose can be administered intravenously, intramuscularly, or orally depending on clinical context 1

Age-Specific Safety Considerations

  • Ondansetron has been studied and used safely in children as young as 6 months of age, making it appropriate for this 26-month-old patient 1
  • Standard weight-based dosing of 0.15 mg/kg (maximum 16 mg) applies for children 2-12 years 1

Clinical Context-Specific Dosing

For Acute Gastroenteritis with Vomiting

  • 0.2 mg/kg orally (approximately 2.8 mg for this patient) can be given at 8-hour intervals if treating gastroenteritis-related vomiting 2
  • This higher dose of 0.2 mg/kg has demonstrated significant reduction in vomiting episodes compared to placebo 2

For Chemotherapy-Induced Nausea

  • Use the standard 0.15 mg/kg dose (2.1 mg for this patient) 1
  • Combination with dexamethasone significantly improves antiemetic efficacy in chemotherapy settings 1

Formulation and Administration

  • Oral suspension is available at 6 mg/mL concentration, so for a 2.1 mg dose, administer approximately 0.35 mL 1
  • Can be administered without regard to meals, though food may improve GI tolerability 1

Critical Safety Warnings

  • Special caution is warranted in children with heart disease due to potential QT interval prolongation 1
  • The maximum single dose is 16 mg regardless of weight 1
  • Severe toxicity including seizures has been reported in infants following overdose, emphasizing the importance of accurate weight-based dosing 3

Dosing Frequency

  • Dosing intervals depend on clinical indication: every 8 hours for gastroenteritis or chemotherapy-related nausea 2, 1
  • For single-dose prophylaxis (e.g., before procedures), one dose 30 minutes prior is sufficient 1

References

Guideline

Ondansetron Dosing in Pediatric Patients

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Research

Obtundation and seizure following ondansetron overdose in an infant.

Clinical toxicology (Philadelphia, Pa.), 2008

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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