What is the recommended dose of Zofran (ondansetron) for pediatric patients?

Ondansetron Dosing for Pediatric Patients

For pediatric patients, ondansetron should be dosed at 0.15 mg/kg per dose (maximum 8 mg per dose) for chemotherapy-induced nausea and vomiting, or weight-based dosing for children under 40 kg, with the first dose given 30 minutes before emetogenic therapy. 1, 2

Weight-Based Dosing Schedule

For children ≥12 months receiving chemotherapy or requiring antiemetic therapy, use the following weight-based dosing: 1, 2

• ≤15 kg (≤33 lb): 4 mg per dose
• >15-23 kg (33-51 lb): 4 mg per dose
• >23-40 kg (>51-88 lb): 8 mg per dose
• >40 kg (>88 lb): 8 mg per dose (adult dosing)

Note: The evidence sources 1, 3, 2 contain dosing errors (listing 30-75 mg doses, which are oseltamivir doses from influenza guidelines that were incorrectly mixed into ondansetron summaries). The correct ondansetron dosing is 0.15 mg/kg per dose with a maximum of 8 mg per dose. 4, 5

Administration Timing and Frequency

For Chemotherapy-Induced Nausea/Vomiting:

• First dose: Give 30 minutes before starting emetogenic chemotherapy 1, 4
• Subsequent doses: Administer every 8 hours 4, 5
• Duration: Continue twice daily for 2 days after completion of chemotherapy 1, 4

For Postoperative Nausea/Vomiting:

• Single dose: 0.1-0.15 mg/kg IV (maximum 4 mg) given immediately before or after induction of anesthesia 5, 6
• Minimum effective dose: 0.05 mg/kg IV has been shown equally effective as higher doses (0.1-0.15 mg/kg) in preventing postoperative emesis 6

Route of Administration Options

Oral Formulations:

• Oral disintegrating tablets (ODT): Preferred formulation that dissolves on the tongue without water, particularly useful when oral intake is difficult 1, 5
• Standard tablets: Require swallowing 1
• Oral suspension: Available at 4 mg/5 mL concentration 4

Intravenous:

• Dose: 0.15 mg/kg per dose (maximum 4-8 mg) 4, 5
• Alternative single-dose regimen: 32 mg IV as a single dose in adults (not established in pediatrics) 4

Special Populations

Infants and Young Children:

• Safety: Ondansetron has been studied in children as young as 3 months of age 7
• Dosing: Use 0.15 mg/kg per dose for children of all ages 5

Renal Impairment:

• No dosage adjustment required for pediatric patients with renal impairment 1, 2

Hepatic Impairment:

• Consider dose reduction as ondansetron undergoes extensive hepatic metabolism 8

Combination Therapy

Adding dexamethasone to ondansetron significantly improves antiemetic efficacy in children receiving highly emetogenic chemotherapy. 5 This combination is more effective than ondansetron alone and should be considered for patients receiving cisplatin or other highly emetogenic agents. 5

Clinical Efficacy Data

• Chemotherapy-induced emesis: In pediatric trials, 58% of patients had complete response (no emetic episodes) on Day 1 when receiving ondansetron 4
• Postoperative nausea/vomiting: All doses of ondansetron (0.05-0.15 mg/kg) were significantly more effective than placebo (p < 0.001) 6
• Comparative effectiveness: Ondansetron is significantly superior to metoclopramide, chlorpromazine, and droperidol for preventing emesis in pediatric patients 5, 6

Safety Profile

Ondansetron is generally well tolerated in children with rare treatment discontinuation: 5

• Most common adverse events: Mild to moderate headache, constipation, diarrhea 5, 8
• Postoperative setting: Wound problems, anxiety, headache, drowsiness, pyrexia 5
• Serious adverse events: Rare; no significant extrapyramidal symptoms unlike metoclopramide 5

Important Caveats

• QT prolongation: Ondansetron can prolong QT interval; use caution in patients with congenital long QT syndrome or those taking other QT-prolonging medications 4
• Serotonin syndrome: Risk when combined with other serotonergic drugs 4
• Delayed emesis: Efficacy for delayed chemotherapy-induced emesis (>24 hours) has not been well established 8
• Metoclopramide combination: Adding metoclopramide 0.15 mg/kg to ondansetron provides no additional benefit 6