Medications
Pegfilgrastim-bmez (Ziextenzo)
A self-injected biosimilar of pegfilgrastim (a Neulasta biosimilar, Ziextenzo) — a long-acting white-blood-cell growth factor given once per chemotherapy cycle to lower the chance of infection from a low neutrophil count (febrile neutropenia).
How Medicare covers it
Part D (forms used at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.
| Coverage details | |
|---|---|
| Part B status | No pegfilgrastim-bmez row in the CMS Part B Spending by Drug HCPCS file (RY26, data through 2024) — no J-code basis; coverage path is Part D. |
| Medicare Advantage | Most Medicare Advantage plans that include drug coverage (MAPD plans) use the same formulary-and-tier system; the plan's own drug list decides coverage and copay — check the plan's formulary. |
| Medicare Supplement (Medigap) | Medicare Supplement (Medigap) plans sold today do not include prescription drug coverage; drug coverage comes from Part D or an MAPD plan. |
What it treats
Ziextenzo (pegfilgrastim-bmez), a biosimilar to Neulasta (pegfilgrastim), has two uses in adults and pediatric patients aged newborn and older: (1) to decrease the incidence of infection, as shown by febrile neutropenia (fever with a low neutrophil count), in patients with non-myeloid cancers who are receiving myelosuppressive anti-cancer drugs that are associated with a clinically significant incidence of febrile neutropenia; and (2) to increase survival in patients acutely exposed to myelosuppressive doses of radiation (hematopoietic subsyndrome of acute radiation syndrome). It is not indicated for mobilizing peripheral blood progenitor cells for stem cell transplantation.
What it is for, in depth
Ziextenzo is a biosimilar of Neulasta (pegfilgrastim), which means it is highly similar to Neulasta with no clinically meaningful differences. Its main use is for people with cancers that are not myeloid cancers who are getting chemotherapy that strongly lowers the white blood cell count, putting them at risk of febrile neutropenia — fever when infection-fighting neutrophils are at their lowest, which can be life-threatening. It is a supportive care drug, not a cancer treatment: one shot per chemotherapy cycle shortens the low-count period and lowers the chance of infection, and the label covers adults and pediatric patients from newborn and older for this use. Ziextenzo also carries the second pegfilgrastim use, increasing survival in people acutely exposed to bone-marrow-damaging doses of radiation, given as two shots one week apart. It comes only as a 6 mg/0.6 mL single-dose prefilled syringe for injection under the skin.
How it works
It is a leukocyte growth factor, also called a colony-stimulating factor. It binds to receptors on blood-forming cells in the bone marrow and tells them to make more neutrophils, a type of white blood cell that fights infection. That shortens the time the white blood cell count stays dangerously low after chemotherapy.
How it is taken
For chemotherapy patients who are adults of any weight or children weighing at least 45 kg, the dose is a single 6 mg shot under the skin (subcutaneous injection) once per chemotherapy cycle, and it must not be given between 14 days before and 24 hours after chemotherapy. For patients acutely exposed to myelosuppressive doses of radiation, the dose is two 6 mg shots under the skin one week apart, with the first dose given as soon as possible after suspected or confirmed exposure. Ziextenzo comes only as a 6 mg/0.6 mL single-dose prefilled syringe for manual use.
Common side effects
The most common side effects (at least 5% more often than with placebo in trials) are bone pain and pain in an arm or leg.
Serious warnings
Serious risks include splenic rupture, which can be fatal — report pain in the left upper belly or left shoulder tip; acute respiratory distress syndrome (ARDS), a serious lung problem; serious allergic reactions including anaphylaxis; severe and sometimes fatal sickle cell crises in people with sickle cell disorders; glomerulonephritis, a kidney problem; very high white blood cell counts (leukocytosis); low platelet counts (thrombocytopenia); capillary leak syndrome; a possible growth-stimulating effect on tumor cells; myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), which are monitored for in patients with breast and lung cancer who also get chemotherapy and/or radiation; and aortitis, inflammation of the aorta.
Who should be careful
Ziextenzo must not be used by anyone who has had a serious allergic reaction to a pegfilgrastim product or a filgrastim product. Tell your doctor if you have a sickle cell disorder, kidney problems, or breathing problems, and report left upper belly or shoulder pain, fever with breathing trouble, or signs of an allergic reaction right away. Tell your doctor if you are pregnant or breastfeeding.
Major interactions
The label has no drug interactions section and lists no major drug interactions. The main timing rule is about chemotherapy itself: this drug must not be given in the period from 14 days before until 24 hours after a dose of cytotoxic chemotherapy.
Cost and saving notes
If this drug is covered under your Medicare Part D plan and the cost is high, you can ask your plan for a tier exception to pay a lower cost share. If you have limited income, Extra Help (the Part D Low-Income Subsidy) can lower your Part D premiums and drug costs. In 2027, your total yearly out-of-pocket spending on covered Part D drugs is capped at $2,400, and you can spread those costs out in monthly payments through the Medicare Prescription Payment Plan.
Why it is in its tier
Pegfilgrastim-bmez (Ziextenzo) sits on Tier 5 in 97.44% of the plans that list it (38 of 39 listing plans). Tier 5 is the specialty tier — instead of a flat copay, patients usually pay a percentage of the drug's cost (coinsurance), which is why specialty drugs feel expensive even with coverage. The data-visible drivers: It is a brand-only product with no generic version in the formulary data, and the CMS dashboard puts its average Part D spending at about $12,767 per beneficiary for 2024 — a high-cost drug, which matches where plans place it. Only 0.71% of Part D plans list it at all, so many readers will find their plan does not list it and covers a similar drug instead. The tier shown is the most common one; individual plans vary.
Sources
- ZIEXTENZO (PEGFILGRASTIM-BMEZ) INJECTION [SANDOZ INC] — DailyMed
- MedlinePlus — National Library of Medicine
- MedlinePlus — Pegfilgrastim Injection
What official patient guides say
Pegfilgrastim-bmez (Ziextenzo) is an injection under the skin, not a pill, so you can keep your normal diet. Your doctor sets the exact timing around your chemotherapy — for chemo patients the label dose is a single shot once per chemotherapy cycle, given with a single-dose prefilled syringe. A nurse may give the shot, or you may be trained to give it yourself at home. Do not shake the syringe, and always check the liquid before you inject: do not use it if it looks cloudy or discolored, has particles in it, or is past its expiration date. Use each syringe only once, even if liquid is left in it, and put used needles and syringes in a puncture-resistant container. MedlinePlus gives no catch-up rule — if you miss a scheduled home dose, ask your doctor what to do instead of doubling up. Store Ziextenzo in the refrigerator in its carton, away from direct sunlight, and do not freeze it; it may sit at room temperature for up to 5 days. Bone pain and pain in the arms or legs are common.
Part D formulary coverage
| Formulary summary | |
|---|---|
| Most common tier | 5 |
| Plans listing this drug | 39 |
| Total Part D plans | 5495 |
| Share of plans listing it | 0.71 |
| Formularies listing it | 6 |
| Tier | Plans |
|---|---|
| Tier 1 | 1 plans |
| Tier 5 | 38 plans |
Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.
What you pay
| With Medicare Part D | |
|---|---|
| Most common tier | Tier 5 |
| Typical coinsurance | 30.0% of the price |
| Based on | 37 plans that cover this drug · 2027 plan year |
A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.
Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-08
Similar medications
Other medications in the same FDA pharmacologic class (Leukocyte Growth Factor):
Read next
Part D spending averages (2024)
| Brand name | Generic name | Total claims 2024 | Total spending 2024 | Total beneficiaries 2024 | Rank by beneficiaries 2024 |
|---|---|---|---|---|---|
| Ziextenzo | PEGfilgrastim-Bmez | 556 | 2.50237e+06 | 196 | 2475 |
Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30
Companies covering this drug
39 plans from 10 companies list this drug on a formulary for 2027. Search by company or plan name, or filter by tier. Cost sharing is the plan's published amount for this drug's tier in the initial coverage stage (1-month retail supply), where the plan publishes it; a blank means the plan does not publish it.
| Company | Plan | Tier | Copay | Coinsurance |
|---|
A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.
Coverage and costs change. Drug lists (formularies), tiers, and copays can change during the year and differ by plan. Always check with your insurance company or plan directly to confirm what is covered and what you will pay.
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