Fosnetupitant / Palonosetron
Fosnetupitant and palonosetron is a two-drug combination used to prevent nausea and vomiting caused by cancer chemotherapy, including highly emetogenic (strongly nausea-causing) regimens.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
📖 Fosnetupitant / Palonosetron: Patient Information Guide
A plain-language walkthrough of Fosnetupitant / Palonosetron — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Fosnetupitant/palonosetron (Akynzeo) is a combination medication used in adults to prevent chemotherapy-induced nausea and vomiting.
- Akynzeo for injection (fosnetupitant/palonosetron, given intravenously): prevents both acute (same-day) and delayed (multi-day) nausea and vomiting from highly emetogenic cancer chemotherapy, including cisplatin-based regimens — used with initial and repeat cycles.
- Akynzeo for injection has not been studied for nausea and vomiting associated with anthracycline plus cyclophosphamide chemotherapy.
- All uses of Akynzeo for injection require co-administration with dexamethasone as part of the antiemetic regimen.
⚙️How it works▾
Fosnetupitant/palonosetron works by blocking two separate chemical pathways that trigger nausea and vomiting during cancer chemotherapy. Palonosetron strongly binds to serotonin receptors (5-HT3 receptors) in the gut and brain. When chemotherapy stimulates the release of serotonin from cells in the small intestine, palonosetron prevents that serotonin from firing the vomiting reflex — controlling acute-phase nausea. Fosnetupitant is converted by the body into netupitant, which blocks NK-1 receptors (neurokinin-1 receptors) widely distributed throughout the nervous system. These receptors are activated by a chemical called substance P and are the primary driver of delayed nausea and vomiting that can persist for days after treatment. By targeting both pathways simultaneously, the combination provides broader protection than either drug alone.
💊How it's taken▾
Akynzeo for injection is given by a healthcare team as a single intravenous (IV) infusion before each chemotherapy cycle — not at home. The infusion runs over 30 minutes and begins 30 minutes before chemotherapy starts. It is always paired with dexamethasone on the day of chemotherapy, and dexamethasone may continue for a few days afterward depending on the regimen.
- Akynzeo for injection requires dilution by pharmacy or clinical staff before it can be infused.
- Akynzeo injection (Ready-to-Use vial) does not require dilution but must be used immediately after the vial is opened.
- Do not mix either form with IV solutions containing calcium or magnesium.
- Your care team will determine the full schedule — follow their instructions exactly for each cycle.
🤒Side effects — in detail▾
The most commonly reported side effects with Akynzeo include:
- Headache
- Fatigue (tiredness)
- Weakness (asthenia)
- Indigestion or upset stomach (dyspepsia)
- Constipation
- Skin redness (erythema)
More serious reactions require prompt attention: seek emergency care for signs of a severe allergic reaction (anaphylaxis) such as throat swelling, difficulty breathing, or sudden low blood pressure. Contact your doctor immediately if you develop symptoms of serotonin syndrome — agitation, rapid heartbeat, high fever, muscle twitching or stiffness — especially if you also take antidepressants or other serotonergic medicines.
⚠️Warnings & precautions▾
Serotonin syndrome is the most critical warning. Combining Akynzeo with other drugs that raise serotonin levels — such as SSRIs, SNRIs, MAO inhibitors, tramadol, fentanyl, lithium, mirtazapine, or IV methylene blue — can cause this potentially fatal condition. Symptoms include mental confusion, agitation, hallucinations, rapid heart rate, high temperature, sweating, and muscle problems. If serotonin syndrome is suspected, Akynzeo must be stopped and supportive care started immediately.
Serious allergic reactions, including anaphylaxis, have been reported with palonosetron, even in patients with no previous allergy to similar drugs. Additionally, netupitant inhibits the CYP3A4 liver enzyme for up to six days after a single dose, which can significantly raise blood levels of many co-administered medications — including certain chemotherapy drugs — potentially increasing their toxicity. Your prescriber should review all your medications before each cycle.
🔀What it interacts with▾
Akynzeo can interact with a wide range of medications because it affects important liver enzymes. Key interactions include:
- CYP3A4 substrate drugs (e.g., docetaxel, paclitaxel, etoposide, irinotecan, cyclophosphamide, vincristine, midazolam, alprazolam, triazolam): netupitant raises their blood levels for up to 6 days, which may increase side effects — dose reduction of those drugs may be needed.
- Dexamethasone: always co-administered with Akynzeo, but at a reduced dose because netupitant more than doubles its exposure in the body.
- Strong CYP3A4 inducers (e.g., rifampin): reduce netupitant blood levels significantly, potentially making Akynzeo less effective — avoid this combination.
- Strong CYP3A4 inhibitors (e.g., ketoconazole): increase netupitant exposure, though no dose adjustment is required for a single Akynzeo dose.
- Serotonergic drugs (SSRIs, SNRIs, MAO inhibitors, mirtazapine, tramadol, fentanyl, lithium, IV methylene blue): increased risk of serotonin syndrome — use with caution and monitor closely.
- Warfarin: effects on INR and clotting time have not been fully studied; monitor INR regularly and adjust warfarin dose as needed.
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Severe liver disease: Akynzeo should be avoided in patients with severe hepatic (liver) impairment.
- Severe kidney disease or end-stage renal disease: Akynzeo should be avoided.
- Pregnancy: Animal studies with fosnetupitant and netupitant showed potential harm to developing offspring; advise your doctor if you are pregnant or could become pregnant, as this drug may pose a risk to the fetus.
- Breastfeeding: It is unknown whether this drug passes into breast milk; discuss the risks and benefits with your doctor.
- Children (under 18): Safety and effectiveness have not been established; Akynzeo is not approved for pediatric use.
- Older adults (65+): Clinical studies showed a similar safety and efficacy profile to younger patients; no special dose adjustment is noted, but inform your care team of all medications.
- Previous allergy to 5-HT3 receptor antagonists: Allergic reactions have occurred with palonosetron even in patients without a known prior allergy to similar drugs — alert your care team to any past reactions.
🚑If you take too much▾
If too much Akynzeo is given, supportive care and monitoring should be provided. Because Akynzeo itself prevents vomiting, trying to induce vomiting as a treatment would not be effective. Due to how widely this drug is distributed throughout the body, dialysis is unlikely to remove meaningful amounts of the drug and is not expected to help in an overdose situation.
📡Pharmacodynamics — effects in the body▾
At the recommended intravenous dose, Akynzeo for injection does not cause a clinically meaningful change in the heart's electrical rhythm (QT interval), which is reassuring from a cardiac safety standpoint. Netupitant has been shown to cross into the brain and occupy NK-1 receptors at high levels — over 90% occupancy within the first six hours after dosing — and that occupancy remains substantial for several days, which explains how a single pre-chemotherapy dose can protect against delayed nausea that persists well after treatment. Palonosetron strongly and selectively binds to 5-HT3 receptors with little effect on other receptor types, which helps keep its side effect profile focused.
🔬Pharmacokinetics — how your body processes it▾
When Akynzeo for injection is given intravenously, peak blood levels of both netupitant (converted from fosnetupitant) and palonosetron are reached by the end of the 30-minute infusion. Netupitant is extensively distributed throughout the body, is more than 99% bound to proteins in the blood, and is eliminated slowly — its half-life (the time for blood levels to fall by half) is roughly 80–96 hours, meaning it stays active in the body for several days after a single dose. Palonosetron is similarly widely distributed and also has a long half-life, contributing to its extended effectiveness. Netupitant is primarily broken down by the liver enzyme CYP3A4; palonosetron is mainly metabolized by CYP2D6 and to a lesser extent by CYP3A4 and CYP1A2.
📦How to store it▾
AKYNZEO capsules should be stored at 20 °C to 25 °C (68 °F to 77 °F); excursions permitted from 15 °C to 30 °C (59 °F to 86 °F) . Store AKYNZEO for injection in carton, protected from light at 2° to 8°C ( F to 46.
📄 Written from Fosnetupitant / Palonosetron’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Fosnetupitant / Palonosetron — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is Akynzeo for injection, and why am I getting it before chemo? ▾
Will I get Akynzeo every time I have chemo, and how is it given? ▾
What side effects should I expect, and which ones mean I should call someone? ▾
I take an antidepressant. Is that a problem with Akynzeo? ▾
Does Akynzeo interact with any of my other medications? ▾
Is Akynzeo safe if I'm pregnant or trying to get pregnant? ▾
Is Fosnetupitant / Palonosetron available over the counter? ▾
When was Fosnetupitant / Palonosetron first available? ▾
💬 Answers drafted from Fosnetupitant / Palonosetron’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Fosnetupitant / Palonosetron comes
Fosnetupitant / Palonosetron is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Injection
How this form is used
- Akynzeo for injection is used to prevent acute and delayed nausea and vomiting associated with initial and repeat courses of highly emetogenic cancer chemotherapy in adults.
- Akynzeo for injection is always given in combination with dexamethasone.
- Akynzeo for injection has not been studied for nausea and vomiting from anthracycline plus cyclophosphamide chemotherapy.
- Akynzeo for injection must be diluted before use and is infused intravenously over 30 minutes, starting 30 minutes before chemotherapy.
- Akynzeo injection is also available as a Ready-to-Use vial (no dilution required) or a To-be-Diluted vial; each version has specific preparation steps that must be followed by healthcare staff.
- Akynzeo for injection is incompatible with solutions containing calcium or magnesium (e.g., Lactated Ringer's solution); only use compatible solutions such as 0.9% sodium chloride or 5% dextrose.
- Akynzeo for injection contains no preservatives and is for single use only; once prepared, infusion must begin within 24 hours.
📊 Fosnetupitant / Palonosetron across the U.S. market
How Fosnetupitant / Palonosetron appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
📈 How widely Fosnetupitant / Palonosetron is used
A general measure of how commonly Fosnetupitant / Palonosetron is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Fosnetupitant / Palonosetron is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Fosnetupitant / Palonosetron prescribed? Of the 1,597 medications we measure, Fosnetupitant / Palonosetron ranks #978 by Medicaid prescriptions — more than 39% of them.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Fosnetupitant / Palonosetron, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 3 of 3 listed Fosnetupitant / Palonosetron NDCs with Medicaid activity.
🔍 Compare Fosnetupitant / Palonosetron products
A representative set of FDA-listed product records for Fosnetupitant / Palonosetron — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Injection | ||||
| FOSNETUPITANT 260 mg/1; PALONOSETRON HYDROCHLORIDE 0.28 mg | Intravenous | Helsinn Therapeutics (U.S.), Inc. | NDA | View NDC → |
| FOSNETUPITANT 260 mg/20 mL; PALONOSETRON HYDROCHLORIDE 0.28 mg/20 mL | Intravenous | Helsinn Therapeutics (U.S.), Inc. × 4 listings | NDA | View NDC → |
| 260; 0.28 mg/1; mg | Intravenous | Helsinn Therapeutics (U.S.), Inc. × 2 listings | NDA | View NDC → |
| 260; 0.28 mg/20 mL; mg/20 mL | Intravenous | Helsinn Therapeutics (U.S.), Inc. × 3 listings | NDA | View NDC → |
Showing 10 of 10 products — FDA National Drug Code Directory. See every product, package size and price: browse all 10 Fosnetupitant / Palonosetron NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Fosnetupitant / Palonosetron — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Fosnetupitant / Palonosetron in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Fosnetupitant / Palonosetron went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
📦 Supply & shortage status
Whether Fosnetupitant / Palonosetron is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
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🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Helsinn Therapeutics (U.S.), Inc. is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.