Ondansetron (Zofran) Administration Protocol
Ondansetron should be administered at a dose of 8 mg IV or orally every 8 hours for most clinical scenarios, with IV administration preferred for patients unable to tolerate oral intake. 1, 2
Dosing by Route of Administration
Intravenous Administration
- For IV administration, dilution in 50 mL of 5% Dextrose Injection or 0.9% Sodium Chloride Injection is required before administration 1
- Standard IV dose is 8 mg infused over 15 minutes beginning 30 minutes before the start of emetogenic therapy 1
- For inpatients with breakthrough symptoms, ondansetron can be given as an 8-mg IV bolus followed by 1 mg/hour continuous infusion 2
- For severe hepatic impairment, maximum daily dose should be limited to 8 mg 1
Oral Administration
- Standard oral dose is 8 mg every 8 hours 2, 3
- For high emetogenic risk chemotherapy, 16-24 mg PO can be given once before chemotherapy 4
- Oral administration should occur at least 30 minutes before anticipated nausea/vomiting trigger (e.g., chemotherapy) 5
- Available as tablets, oral dissolving tablets (ODT), and oral soluble film that dissolves rapidly on the tongue without water 6
Dosing by Clinical Scenario
Chemotherapy-Induced Nausea and Vomiting
- For high emetogenic chemotherapy:
- For moderate emetogenic chemotherapy:
- For low emetogenic chemotherapy:
- Single dose of 8 mg IV or PO before chemotherapy, with additional doses only as needed 3
Multi-Day Chemotherapy Regimens
- Administer ondansetron daily during chemotherapy and for 2 days thereafter 3
- For pediatric patients (6 months and older): 0.15 mg/kg per dose for 3 doses, with maximum of 16 mg per dose 1
Breakthrough Nausea and Vomiting
- For breakthrough symptoms despite prophylaxis, ondansetron 8 mg IV or PO can be given, titrated up to maximum of 16 mg daily 3, 7
- Adding medications from different classes (e.g., olanzapine, metoclopramide, prochlorperazine) is more effective than increasing ondansetron dose 2, 8
Common Pitfalls and Caveats
- PRN-only dosing is less effective than scheduled dosing for prevention of nausea and vomiting 2
- Oral route may not be feasible during active vomiting; IV administration is preferred in these situations 2
- Ondansetron commonly causes constipation, which may complicate management in certain scenarios 2, 7
- Bioavailability of oral ondansetron is only about 60% compared to IV administration due to first-pass metabolism 5
- Efficacy is maintained over multiple chemotherapy cycles 7, 9
Special Considerations
- For radiation therapy-induced nausea/vomiting, administer once or twice daily on treatment days and once daily on the day after each treatment 3
- For elderly patients, no dosage adjustment is required despite decreased clearance 5
- For patients with severe hepatic impairment, maximum daily dose should be limited to 8 mg 1