Zanidatamab-Hrii
Zanidatamab-hrii (Ziihera) is an intravenous HER2-directed antibody used to treat certain HER2-positive stomach, esophageal and biliary tract cancers.
🧬 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 →
Zanidatamab-hrii (Ziihera) is a newer specialist IV antibody, on the U.S. market since about 2024, for HER2-positive stomach and esophageal cancer and previously treated HER2-positive bile duct cancer; it grabs two spots on the HER2 protein, pulling it inside the cancer cell and calling in the immune system. It is usually given with chemotherapy, so expect a demanding course; diarrhea is what most people notice, along with nausea, tiredness and poor appetite. The boxed warning covers severe, sometimes fatal diarrhea with chemotherapy (higher risk with tislelizumab and in people 65 and older) and harm to an unborn baby, so call your care team as soon as diarrhea starts.
Clinical pearls
- Use effective contraception during treatment and for 4 months after the last dose, because the drug lingers in the body that long.
- If your regimen includes fluorouracil, it should run as a slow infusion rather than a quick bolus push, which can worsen diarrhea.
- Low potassium is a common side effect, and diarrhea makes it worse, so expect regular blood tests to check it.
- It can weaken the heart’s pumping, so you will have heart scans before and during treatment; report new breathlessness or swelling.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Ziihera can cause severe diarrhea, including life-threatening and fatal cases, when given with fluoropyrimidine- and platinum-containing chemotherapy, with or without tislelizumab-jsgr. You will be given loperamide in the first cycle to help prevent it. Your doctor may pause, lower or stop Ziihera depending on severity. Adults 65 and older are at higher risk.
It can also harm an unborn baby. Women who could become pregnant need effective contraception, and your doctor should be told about any possible pregnancy.
Patient information guide A plain-language walkthrough of Zanidatamab-Hrii, written from its FDA label.
What Zanidatamab-Hrii is used for
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Zanidatamab-hrii treats certain HER2-positive cancers in adults.
- Ziihera, with fluoropyrimidine- and platinum-containing chemotherapy and tislelizumab-jsgr, is for first-line treatment of HER2-positive unresectable locally advanced or metastatic gastric, gastroesophageal junction or esophageal adenocarcinoma.
- Ziihera, with chemotherapy alone, is for first-line treatment of HER2-positive (IHC 3+) disease of the same type.
- Ziihera alone is for previously treated, unresectable or metastatic HER2-positive (IHC 3+) biliary tract cancer. This is an accelerated approval, which depends on confirmation of benefit in further trials.
How Zanidatamab-Hrii works
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Zanidatamab-hrii is a bispecific antibody that binds two different areas of the HER2 protein on cancer cells. This causes HER2 to cluster and be pulled inside the cell, reducing it on the surface.
It also activates immune responses that kill tumor cells. In lab and animal studies, this slowed tumor growth and caused cell death.
Zanidatamab-Hrii dosage
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Ziihera is given by IV infusion in a healthcare setting. It is not taken by mouth.
- Stomach and esophageal cancers: given every 2 or 3 weeks, based on body weight, with chemotherapy.
- Biliary tract cancer: given alone every 2 weeks.
- Premedication is given 30 to 60 minutes before each dose.
- Missed dose with chemotherapy: usually given as soon as possible if 7 days or fewer late. If later, it is held until the next cycle. Your team will advise you.
Dosing details from the FDA-approved label
From the Zanidatamab-Hrii prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Gastroesophageal Adenocarcinoma (GEA): patients weighing less than 70 kg (
- ZIIHERA 1,800 mg intravenously every 3 weeks or 1,200 mg every 2 weeks, in combination with fluoropyrimidine- and platinum-containing chemotherapy, with or without tislelizumab-jsgr, until disease progression or unacceptable toxicity
- Weight
- Gastroesophageal Adenocarcinoma (GEA): patients weighing 70 kg or greater (≥70 kg)
- ZIIHERA 2,400 mg intravenously every 3 weeks or 1,600 mg every 2 weeks, in combination with fluoropyrimidine- and platinum-containing chemotherapy, with or without tislelizumab-jsgr, until disease progression or unacceptable toxicity
- Weight ≥70 kg; dose reduction for adverse reactions: 1,800 mg every 3 weeks or 1,200 mg every 2 weeks
- Biliary Tract Cancer
- ZIIHERA 20 mg/kg administered as an intravenous infusion once every 2 weeks until disease progression or unacceptable toxicity
- Dose reduction for adverse reactions: 15 mg/kg every 2 weeks
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION • Premedicate all patients to reduce the risk of infusion-related reactions (IRRs). ( 2.2 ) • Administer loperamide during the first cycle to patients receiving ZIIHERA in combination with fluoropyrimidine- and platinum-containing chemotherapy for diarrhea prophylaxis. ( 2.2 ) Gastroesophageal Adenocarcinoma (GEA): • Patients weighing less than 70 kg: ZIIHERA 1,800 mg intravenously every 3 weeks or 1,200 mg every 2 weeks infusion in combination with fluoropyrimidine- and platinum-containing chemotherapy, with or without tislelizumab-jsgr. ( 2.3 ) • Patients weighing 70 kg or greater: ZIIHERA 2,400 mg intravenously every 3 weeks or 1,600 mg every 2 weeks in combination with fluoropyrimidine- and platinum-containing chemotherapy, with or without tislelizumab-jsgr. ( 2.3 ) Biliary Tract Cancer: ZIIHERA 20 mg/kg intravenously every 2 weeks. ( 2.3 ) 2.1 Patient Selection HER2-Positive Gastroesophageal Adenocarcinoma (GEA) Select patients for treatment of unresectable locally advanced or metastatic GEA based on HER2-positive status (IHC 3+ or IHC 2+/ISH+), as detected by FDA-authorized tests [see Clinical Studies ( 14.1 )] . Information on FDA-authorized tests for HER2 protein expression and gene amplification in gastric, gastroesophageal junction, or esophageal adenocarcinoma is available at: http://www.fda.gov/CompanionDiagnostics . Biliary Tract Cancer (BTC) Select patients for treatment of unresectable or metastatic biliary tract cancer based on HER2-positive (IHC 3+) tumor specimens, as detected by an FDA-authorized test [see Clinical Studies ( 14.2 )] . Information on FDA-authorized tests for HER2 protein expression in biliary tract cancers is available at: http://www.fda.gov/CompanionDiagnostics. 2.2 Premedications and Important Administration Information Premedicate all patients 30 to 60 minutes prior to each dose of ZIIHERA to reduce the risk of infusion-related reactions [see Warnings and Precautions ( 5.4) ] : • Administer acetaminophen, an antihistamine (such as diphenhydramine) and a corticosteroid (such as hydrocortisone). ZIIHERA in combination with fluoropyrimidine- and platinum-containing chemotherapy with or without tislelizumab-jsgr Antidiarrheal prophylaxis: • Administer loperamide 4 mg twice daily beginning on Day 1 and continue for at least 7 days during the first cycle of treatment.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Zanidatamab-Hrii side effects
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Common side effects include:
Common side effects
- Diarrhea
- Nausea and vomiting
- Decreased appetite
- Fatigue
- Low potassium
- Rash
- Numbness or tingling in hands and feet (peripheral neuropathy)
- Infusion-related reactions
- Abdominal pain (when used alone)
When to get medical help
- Call your care team right away if you have diarrhea. Drink more fluids and start an anti-diarrhea medicine as directed.
- Get help for severe, life-threatening or long-lasting diarrhea, or signs of dehydration.
- Report symptoms during or after an infusion, since infusion reactions can be serious.
- Report new heart symptoms, because Ziihera can lower how well the heart pumps (left ventricular dysfunction).
- Tell your doctor right away if you are or may be pregnant.
Zanidatamab-Hrii warnings and precautions
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- Severe diarrhea can be life-threatening or fatal, especially with chemotherapy and tislelizumab-jsgr, and in people 65 and older.
- Embryo-fetal toxicity: can harm an unborn baby.
- Left ventricular dysfunction: reduced heart pumping; heart function is checked before and during treatment.
- Infusion-related reactions: monitored during and after infusion.
Zanidatamab-Hrii interactions
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Ziihera is mainly used alongside other cancer drugs, which affects diarrhea risk.
- Chemotherapy (fluoropyrimidine and platinum): raises the risk of severe diarrhea.
- Tislelizumab-jsgr: adds to the risk of severe diarrhea.
- Fluorouracil bolus: may increase diarrhea, so it is given as an infusion instead.
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Zanidatamab-Hrii
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- Pregnancy: not recommended; pregnancy status is checked first.
- Use effective contraception during treatment and for 4 months after the last dose.
- Breastfeeding: discuss with your doctor.
- Heart problems or low ejection fraction: tell your doctor.
- Adults 65 and older: higher risk of severe side effects with chemotherapy and tislelizumab-jsgr.
- Children: safety and effectiveness not established.
What Zanidatamab-Hrii does in the body
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The relationship between drug exposure and both safety and effectiveness has not been fully worked out. At the approved dose, a meaningful increase in the heart's QTc interval (an electrical timing measure) is unlikely.
How your body processes Zanidatamab-Hrii
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Zanidatamab-hrii is given into a vein. It is expected to be broken down into small peptides by the body's normal pathways. Its half-life is about 24 days, and steady levels build up over roughly 16 weeks. Age, sex, body weight, race and mild to moderate liver or kidney impairment did not meaningfully change its levels. The effect of severe kidney or liver impairment is unknown.
How to store Zanidatamab-Hrii
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Store in a refrigerator at 2°C to 8°C (36°F to 46°F) in the original carton until time of reconstitution. Do not freeze.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Zanidatamab-Hrii: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Zanidatamab-Hrii — the kind of thing our pharmacy team would talk through with you at the counter.
What is Ziihera for?
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How will I get it?
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What should I do if I get diarrhea?
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What side effects are common?
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Is it safe in pregnancy?
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Will my heart be checked?
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Is Zanidatamab-Hrii available over the counter?
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When was Zanidatamab-Hrii first available?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Zanidatamab-Hrii on HelloPharmacist
Zanidatamab-Hrii forms and strengths (how it comes)
Zanidatamab-Hrii 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.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Zanidatamab-Hrii inactive ingredients by manufacturer.
Injection
How this form is used
- Ziihera is used with chemotherapy, with or without tislelizumab-jsgr, for first-line treatment of HER2-positive gastroesophageal adenocarcinoma.
- Ziihera alone is used for previously treated HER2-positive biliary tract cancer (accelerated approval).
- Ziihera is given as an intravenous infusion after it is reconstituted and diluted.
- Ziihera is given with premedication before each dose to reduce infusion reactions.
- Ziihera with chemotherapy comes with loperamide in the first cycle to prevent diarrhea.
Zanidatamab-Hrii on the U.S. market: products, makers and brands
How Zanidatamab-Hrii 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.
1 company lists 1 Zanidatamab-Hrii product record with the FDA, mostly as injection; the earliest marketing or approval year on record is 2024. Brand names on the directory include Ziihera; the rest are generics.
How widely Zanidatamab-Hrii is used (Medicaid data)
A general measure of how commonly Zanidatamab-Hrii is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q2 2025 – Q1 2026, summed across every form and brand of the drug.
Think of this as a proxy for how widely Zanidatamab-Hrii 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 Zanidatamab-Hrii prescribed? Of the 1,601 medications we measure, Zanidatamab-Hrii ranks #1,591 by Medicaid prescriptions — more than 1% of them.
Utilization by Zanidatamab-Hrii product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
zanidatamab-hrii 300 MG Injection
Summed across the 1 of 2 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 2698206
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Zanidatamab-Hrii, 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 1 of 2 listed Zanidatamab-Hrii NDCs with Medicaid activity.
Compare Zanidatamab-Hrii products
A representative set of FDA-listed product records for Zanidatamab-Hrii — 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 | ||||
| 50 mg/mL | Intravenous | Jazz Pharmaceuticals, Inc. | BLA | View NDC → |
Showing 1 of 1 products — FDA National Drug Code Directory. See every product, package size and price: browse all 1 Zanidatamab-Hrii NDCs →
Zanidatamab-Hrii side effects reported to the 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 Zanidatamab-Hrii — a signal of what to watch for, not proof the drug caused it.
The effects most often named in FDA reports that mention Zanidatamab-Hrii are chills, infusion related reaction, diarrhoea; about 49% of the reports were classed as serious. These are voluntary reports, so they show what people report, not how often it happens.
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 Zanidatamab-Hrii 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.
Zanidatamab-Hrii FDA approval history
How Zanidatamab-Hrii went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Zanidatamab-Hrii was first approved by the FDA in 2024 (Brand: ZIIHERA · Jazz Pharms). It remains available in U.S. pharmacies today.
Source: Drugs@FDA.
Zanidatamab-Hrii 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.
The FDA’s enforcement reports list no Zanidatamab-Hrii recalls since July 2021.
✅No Zanidatamab-Hrii recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 2698198 1 dose form · 1 strength
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Dose form (SCDF) Injection RxCUI 2698203In current FDA listingsClinical drug / strength (SCD) hrii 300 MGRxCUI 2698206
Look up RxCUI 2698198 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Zanidatamab-Hrii supply and shortage status
Whether Zanidatamab-Hrii 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.
Zanidatamab-Hrii brand names
Zanidatamab-Hrii is sold under one brand name in the FDA directory — Ziihera. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Zanidatamab-Hrii: manufacturers and labelers
One company lists Zanidatamab-Hrii products with the FDA. By number of product records, the largest are Jazz Pharmaceuticals, Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Zanidatamab-Hrii drug class (RxNorm)
Zanidatamab-Hrii belongs to the HER2 (Human Epidermal Growth Factor Receptor 2) inhibitors class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Zanidatamab-Hrii page
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 this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Jazz Pharmaceuticals, Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →