Long-acting 5-HT3 antagonist Pregnancy: No clinical data on exposed pregnancies are available and there is no experience of palonosetron in human pregnancy; animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryonal/foetal development, parturition or postnatal development. Palonosetron should not be used in pregnant women unless it is considered essential by the physician. Breast-feeding should be discontinued during therapy, as there are no data concerning excretion in breast milk. There are no data concerning the effect of palonosetron on fertility.

Palonosetron

Brand names: Aloxi

Palonosetron is a second-generation 5-HT3 receptor antagonist used to prevent acute and delayed nausea and vomiting associated with chemotherapy.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 250 micrograms palonosetron administered as a single intravenous bolus approximately 30 minutes before the start of chemotherapy

Route: Intravenous - injected over 30 seconds

Frequency: Single dose, approximately 30 minutes before the start of chemotherapy

UNIT IS MICROGRAMS. Palonosetron should be used only before chemotherapy administration, and this medicinal product should be administered by a healthcare professional under appropriate medical supervision. The efficacy of palonosetron in the prevention of nausea and vomiting induced by highly emetogenic chemotherapy may be enhanced by the addition of a corticosteroid administered prior to chemotherapy. ELDERLY: no dose adjustment is necessary. HEPATIC IMPAIRMENT: no dose adjustment is necessary. Fetched SPC is Palonosetron 250 micrograms solution for injection (https://www.medicines.org.uk/emc/product/13202/smpc). The fetched UK SPC §4.2 contains NO postoperative nausea and vomiting (PONV) regimen; the US label (openFDA, palonosetron hydrochloride injection) states a PONV dose of 0.075 mg as a single intravenous dose over 10 seconds immediately before the induction of anaesthesia - that is US labelling for a US-licensed indication and must be verified against the relevant UK SPC before use.

Paediatric dose

Dose: 20 micrograms/kg

Route: Single 15 minute intravenous infusion, beginning approximately 30 minutes before the start of chemotherapy

Frequency: Single dose before the start of chemotherapy

Max: The maximum total dose should not exceed 1500 micrograms

UNIT IS MICROGRAMS PER KG, NOT MILLIGRAMS. Exact SPC wording (§4.2, Paediatric population): 'Children and adolescents (aged 1 month to 17 years): 20 micrograms/kg (the maximum total dose should not exceed 1500 micrograms) palonosetron administered as a single 15 minute intravenous infusion beginning approximately 30 minutes before the start of chemotherapy.' Note the different administration time from adults (15 minute infusion in children versus a 30 second bolus in adults). The safety and efficacy of palonosetron in children aged less than 1 month have not been established and no data are available; there are limited data on use in children under 2 years of age. Verify all under-18 dosing against a children's formulary.

Dose adjustments

Renal

No dose adjustment is necessary for patients with impaired renal function. No data are available for patients with end stage renal disease undergoing haemodialysis.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

Contraindications

Hypersensitivity to the active substance or to any of the excipients

Side effects

Headache (9% in adult clinical studies at the 250 microgram dose) - common
Constipation (5%) - common; diarrhoea and dyspepsia also reported
Dizziness - common
Injection site reaction, including burning, induration, discomfort and pain
Cardiac and investigational - tachycardia, bradycardia, extrasystoles, sinus tachycardia, electrocardiogram QT prolonged, elevated transaminases (uncommon)
Hypotension and hypertension (uncommon); hypersensitivity, anaphylaxis and anaphylactic/anaphylactoid reactions and shock (very rare, post-marketing)

Interactions

Serotonergic drugs, including SSRIs and SNRIs - serotonin syndrome (altered mental status, autonomic instability, neuromuscular symptoms) has been described following concomitant use of 5-HT3 receptor antagonists with other serotonergic drugs; monitor for its emergence and, if symptoms occur, discontinue palonosetron and initiate supportive treatment (US label §7.1)
Interactions are taken from the US prescribing information because the fetched eMC bundle contains no §4.5 section - verify against the full UK SPC §4.5

Clinical monograph

How it works

It selectively and with high affinity blocks serotonin 5-HT3 receptors peripherally on vagal afferents and centrally, interrupting the emetic reflex triggered by chemotherapy.

Prescribing in practice

Like other 5-HT3 antagonists it can prolong the QT interval, so use caution in patients with risk factors for arrhythmia or on other QT-prolonging drugs.
It has a long duration of action and is given as a single dose per chemotherapy cycle.
Constipation and headache are common, and serotonin syndrome can occur if combined with other serotonergic agents.

Monitoring

Consider ECG monitoring of the QT interval in at-risk patients and review electrolytes, particularly potassium and magnesium.

Counselling the patient

Tell patients that headache and constipation are common and how to manage them.
Advise patients to report palpitations or symptoms suggesting serotonin syndrome such as agitation or tremor.

Evidence & guidelines

Palonosetron is an established option for chemotherapy-induced nausea and vomiting and features in antiemetic guidelines for moderately and highly emetogenic regimens.

Reference: NICE TA313; ESMO; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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