Ondansetron Dosing for a 20 kg Pediatric Patient
For a 20 kg pediatric patient, administer ondansetron 0.15 mg/kg intravenously, which equals 3 mg per dose. 1
Weight-Based Dosing Regimen
Standard IV dose: 0.15 mg/kg administered intravenously 1, 2
- For this 20 kg patient: 3 mg per dose
- This dose has been validated in multiple large pediatric trials for both chemotherapy-induced and postoperative nausea/vomiting 1
Alternative oral dosing: 0.1 mg/kg orally if IV access is not available 1
- For this 20 kg patient: 2 mg orally
Dosing Frequency and Timing
For chemotherapy-induced nausea/vomiting: Administer three doses on the day of chemotherapy 2
- First dose: 30 minutes before chemotherapy
- Second dose: 4 hours after first dose
- Third dose: 8 hours after first dose
For postoperative nausea/vomiting: Single dose of 0.1-0.15 mg/kg IV administered before or during surgery 1
- Peak antiemetic effect occurs within 1 hour 2
Important Clinical Considerations
Bioavailability: Oral ondansetron has 59% absolute bioavailability with peak plasma concentrations at 1 hour 2
Pediatric clearance: Children have increased clearance compared to adults, which supports the weight-based dosing approach rather than fixed dosing 2
Combination therapy: Ondansetron combined with dexamethasone is significantly more effective than ondansetron alone for chemotherapy-induced nausea 1
Half-life: 3.5 hours in healthy patients, allowing for appropriate dosing intervals 2
Safety Profile
Adverse events: Most commonly headache, constipation, and diarrhea, all typically mild to moderate 1
- In surgical patients: wound problems, anxiety, headache, drowsiness, and pyrexia may occur 1
Tolerability: Ondansetron is generally well tolerated in children and rarely necessitates treatment withdrawal 1
Hepatic metabolism: Undergoes extensive hepatic oxidative metabolism; dose adjustment may be needed in patients with significant liver dysfunction 2