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Ondansetron 💊
📖 About
Always check the BNF link here.
- 💊 Ondansetron is a potent anti-emetic widely used in oncology, post-operative care, and palliative medicine.
- ✅ Particularly effective against chemotherapy- and radiotherapy-induced nausea and vomiting (CINV/RINV) and post-operative nausea/vomiting (PONV).
⚡ Mechanism of Action
- ⛔ 5-HT3 receptor antagonist.
- Blocks serotonin receptors centrally in the chemoreceptor trigger zone (CTZ) and peripherally in the GI tract/vagus nerve.
- ⬇️ Prevents serotonin-mediated stimulation of vomiting pathways.
🩺 Indications & Dosing – Ondansetron (verify in BNF/datasheet)
| Indication | Details |
|---|---|
| 🤢 General Nausea & Vomiting |
Ondansetron
• Dose: 4–8 mg • Route: PO / IV / IM • Frequency: OD–BD (per clinical need) |
| 🎗️ Chemo/Radiotherapy-induced Nausea |
Ondansetron
• 8 mg PO/IV before treatment • Then 8 mg q12h for 1–2 days (protocol dependent) |
| 🏥 Post-operative Nausea/Vomiting (PONV) |
Ondansetron
• 4 mg IV/IM • Given at induction or post-operatively |
- 💧 IV should be given over at least 2–5 min to reduce arrhythmia risk.
🔄 Interactions
- See BNF – avoid with other QT-prolonging drugs (e.g. amiodarone, macrolides, antipsychotics).
- ⚡ May increase risk of serotonin syndrome when combined with SSRIs, SNRIs, MAOIs, or other serotonergic agents.
⚠️ Cautions
- 💔 QT prolongation risk – caution in those with arrhythmias, electrolyte imbalance, or on other QT-prolonging meds.
- 📉 Severe hepatic impairment – max dose 8 mg daily.
- 👶 Neonates/infants – use with caution (immature hepatic metabolism).
🚫 Contraindications
- Hypersensitivity to ondansetron or other 5-HT3 antagonists.
- Concomitant use with apomorphine (severe hypotension and loss of consciousness reported).
💥 Side Effects
- 🤢 Constipation (common).
- 🧠 Headache, dizziness.
- 🌡️ Flushing, hiccups.
- 💔 QT prolongation, arrhythmias (rare but serious).
- ⚡ Rare: serotonin syndrome (with serotonergic drugs), seizures, anaphylaxis.
- 🫁 Rare: transient visual disturbances during IV administration.
📑 References
- BNF: Ondansetron
- MHRA Drug Safety Update: Ondansetron & QT prolongation
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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