[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [5-HT3 receptor antagonists (setrons)](https://durgical.com/en/pharmacology/classes/5-ht3-receptor-antagonists/) › Palonosetron [Pharmacology](https://durgical.com/en/pharmacology/) · [5-HT3 receptor antagonists (setrons)](https://durgical.com/en/pharmacology/classes/5-ht3-receptor-antagonists/) # Palonosetron A long-acting 5-HT3 antagonist given by IV before chemotherapy. Its half-life of about 40 hours also covers the delayed phase after moderate chemotherapy. Updated 2026-11-01 - Class: [5-HT3 receptor antagonists (setrons)](https://durgical.com/en/pharmacology/classes/5-ht3-receptor-antagonists/) - Ion channel: Serotonin 5-HT3A receptor - ATC code: A04AA05 ⇅**Serotonin 5-HT3A receptor**Palonosetron ⓘ Cryo-EM structure of the mouse 5-HT3A receptor with palonosetron in the serotonin pocket; the human receptor's pocket is closely similar. **Target in 3D:** Serotonin 5-HT3A receptor. PDB structure 6Y1Z (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/6Y1Z) · Drag to rotate · pinch to zoom ## Mechanism of action Palonosetron is a 5-HT3 antagonist with very strong affinity for the receptor and little or no affinity for other receptors. It blocks serotonin's action on vagal afferents in the gut and in the brainstem vomiting centres. Its high affinity and long half-life let a single dose protect against both acute and delayed vomiting after moderately emetogenic chemotherapy. - Palonosetron binds the 5-HT3 receptor with very high affinity - Serotonin cannot open the channel on vagal and brainstem neurons - Its long half-life keeps the block for days - A single dose covers acute and delayed vomiting after moderate chemotherapy ## Pharmacokinetics **Distribution** Large volume of distribution; about 62% bound to plasma proteins. **Metabolism** Mainly CYP2D6, and to a lesser extent CYP3A4 and CYP1A2; it does not inhibit or induce CYP enzymes. **Elimination** By both the kidney and metabolism. **Half-life** Mean terminal half-life about 40 hours. ## Indications - Prevention of acute and delayed nausea and vomiting from moderately emetogenic chemotherapy, and of acute nausea and vomiting from highly emetogenic chemotherapy. - Prevention of post-operative nausea and vomiting for up to 24 hours after surgery. ## Adverse effects ### Common - Headache - Constipation - Bradycardia and QT prolongation after surgery ### Serious (rare, important) - Hypersensitivity reactions, including anaphylaxis - Serotonin syndrome, mostly with other serotonergic drugs ## Contraindications - Hypersensitivity to palonosetron ## Key interactions **SSRIs, SNRIs, MAO inhibitors, mirtazapine, fentanyl, lithium, tramadol, IV methylene blue** Serotonin syndrome; palonosetron is stopped if it appears. **QT-prolonging drugs** Possible additive effect on the QT interval. ## What is monitored - Signs of serotonin syndrome when given with serotonergic drugs - Heart rate and ECG after surgery in at-risk patients - Bowel function ## Administration and safety - Single IV dose before chemotherapy or before induction of anaesthesia - Routine post-operative prevention is not used in patients with little expected risk - The infusion line is flushed with normal saline before and after the dose ## Nursing care - Time the dose before chemotherapy starts - Explain that one dose protects for several days, so repeat doses are not given on the following days unless prescribed - Ask about constipation and headache - Watch for agitation, tremor, sweating or fever with serotonergic drugs ## Pregnancy and breastfeeding There are no data in pregnant women; animal studies showed no effect on embryo-fetal development. ## Memory aid «PALONOsetron = PALO (stick) that stays»: a long-acting setron that sticks to the receptor for about 40 hours and covers the delayed phase. ## Test yourself Think of the answer, then tap the question to see it. ## What sets palonosetron apart from ondansetron and granisetron? Very high receptor affinity and a much longer half-life (about 40 hours), so one dose also covers delayed vomiting after moderately emetogenic chemotherapy. ## Through which CYP enzyme is palonosetron mainly metabolised? CYP2D6, with smaller roles for CYP3A4 and CYP1A2. ## Which serious drug interaction is shared by all 5-HT3 antagonists? Serotonin syndrome with serotonergic drugs such as SSRIs, SNRIs, fentanyl or tramadol. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/palonosetron/) ## Related drugs - [Ondansetron](https://durgical.com/en/pharmacology/ondansetron/) - [Granisetron](https://durgical.com/en/pharmacology/granisetron/) - [Aprepitant](https://durgical.com/en/pharmacology/aprepitant/) [← Back to the class: 5-HT3 receptor antagonists (setrons)](https://durgical.com/en/pharmacology/classes/5-ht3-receptor-antagonists/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [DailyMed - PALONOSETRON HYDROCHLORIDE injection, solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=911783eb-91a8-4ef4-bd6f-809211e207d6) (DailyMed (U.S. National Library of Medicine), 2026); [Palonosetron Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a610002.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [RCSB PDB - 6Y1Z: Mouse serotonin 5HT3 receptor in complex with palonosetron](https://www.rcsb.org/structure/6Y1Z) (RCSB Protein Data Bank, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/palonosetron/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/palonosetron/