Ondensetron dose adult
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Ondansetron (Adult Dosing)
Ondansetron is a 5-HT₃ receptor antagonist used primarily as an antiemetic.
Standard Adult Doses
| Indication | Route | Dose | Frequency |
|---|---|---|---|
| Nausea & vomiting (general) | PO | 8 mg | Every 12 hours |
| Nausea & vomiting (general) | IV | 4 mg | Every 8 hours PRN |
| Chemotherapy-induced N&V (highly emetogenic) | IV | 32 mg (or 0.15 mg/kg) | Single dose 30 min before chemo |
| Chemotherapy-induced N&V (moderately emetogenic) | PO | 8 mg | 30 min before chemo, then 8 mg q8h × 2 doses |
| Post-operative N&V (PONV) | IV/IM | 4 mg | Single dose at end of surgery |
| Radiation-induced N&V | PO | 8 mg | 1–2 hours before radiation, then q8h |
Key Points
- Max single IV dose: 16 mg (32 mg single-dose IV no longer recommended due to QT risk)
- Max daily dose: generally 32 mg/day PO; lower limits apply IV
- Renal impairment: no dose adjustment needed
- Hepatic impairment (severe, Child-Pugh C): max 8 mg/day
- ODT (orally disintegrating tablet): same doses as PO tablets
⚠️ Safety: QT Prolongation
Ondansetron prolongs the QT interval. Use caution with:
- Other QT-prolonging drugs (e.g., haloperidol, methadone, fluoroquinolones)
- Hypokalemia / hypomagnesemia
- Congenital long QT syndrome
- Monitor with ECG if combined with other QT-prolonging agents
(Clinical Management and Infection Prevention and Control for Mpox, p. 135)
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