Ondansetron
Zofran
5-HT3 receptor antagonist
Blocks serotonin receptors at vagal afferents and chemoreceptor trigger zone.
Indications
- •PONV prophylaxis + treatment
- •Chemotherapy-induced nausea
- •Pruritus from neuraxial opioids
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| PONV prophylaxis | 4 mg IV at end of case | 0.1 mg/kg IV (max 4 mg) |
| Treatment | 4 mg IV q4–6 h prn | — |
Pharmacokinetics
Onset 30 min. Duration 4–8 h. Hepatic CYP.
Side effects
- !QT prolongation (dose-dependent; max single IV dose 16 mg)
- !Headache
- !Constipation
- !Serotonin syndrome with MAOIs/SSRIs (rare)
Contraindications
- ×Long QT syndrome
- ×Concurrent apomorphine
Clinical pearls
- ★Combine with dex 4–8 mg + droperidol 0.625 mg for high-risk PONV (Apfel score ≥ 3).
- ★ECG-guided dosing in cardiac patients.
Education only — confirm against current package inserts and institutional protocols. Doses assume normal organ function unless otherwise noted.