Alternatives to Releuko If You Can't Fill Your Prescription

Releuko (filgrastim-ayow) is a biosimilar to Neupogen (filgrastim), and if you're having trouble filling your prescription, the good news is that you are not out of options. Several FDA-approved filgrastim products work through the same mechanism and are indicated for the same core uses. Your oncologist can help you switch, but it is important to understand the differences so you can have an informed conversation.

Why Switching Filgrastim Products Isn't as Simple as a Generic Swap

Unlike generic oral medications, biosimilars like Releuko cannot be automatically substituted at the pharmacy. Each filgrastim product has its own FDA approval with its own specific indications. Your pharmacist cannot substitute Zarxio for Releuko without a new prescription from your oncologist. That said, the clinical differences are minimal — your oncologist can write a new prescription for an alternative product quickly.

The Main Alternatives to Releuko

1. Zarxio (Filgrastim-sndz) — The Most Widely Available Biosimilar

Zarxio was the first FDA-approved filgrastim biosimilar, approved in 2015 by Sandoz. It is often the preferred formulary product for most major insurance plans, making it the most widely stocked filgrastim biosimilar in the U.S. Zarxio is approved for all the same indications as Releuko except increasing survival in myelosuppressive radiation exposure. A key advantage: Zarxio prefilled syringes can be stored at room temperature for up to 4 days, giving it a slight practical edge over Releuko (which has a 24-hour room-temperature limit). Typical cost: $200–$350 per injection with insurance or discount programs.

2. Nivestym (Filgrastim-aafi) — The Second Biosimilar Option

Nivestym (filgrastim-aafi), manufactured by Pfizer/Hospira, was FDA-approved in 2018. Like Releuko, it is indicated for chemotherapy-induced neutropenia, AML recovery, bone marrow transplantation support, stem cell mobilization, and chronic severe neutropenia. It is NOT approved for the radiation exposure indication. Nivestym comes in the same vials and prefilled syringe sizes as Neupogen (300 mcg and 480 mcg) and shares the same 24-hour room-temperature stability. It is generally comparably priced to Releuko and Zarxio at $200–$350 per injection with a discount card.

3. Neupogen (Filgrastim) — The Original Reference Product

Neupogen is the original filgrastim product manufactured by Amgen, FDA-approved since 1991. It has the broadest set of approved indications, including all of Releuko's indications PLUS stem cell mobilization and the radiation exposure (hematopoietic acute radiation syndrome) indication that biosimilars lack. Neupogen is significantly more expensive — the wholesale acquisition cost is approximately $400–$800 per injection depending on strength — but Amgen's Safety Net Foundation offers free medication to qualifying uninsured or underinsured patients.

4. Neulasta / Pegfilgrastim Biosimilars — Once-Per-Cycle Option

Neulasta (pegfilgrastim) is not a like-for-like replacement for Releuko — it is a longer-acting, pegylated form of filgrastim. However, in some clinical contexts, your oncologist may prefer it because it only requires a single injection once per chemotherapy cycle, rather than daily injections. Multiple Neulasta biosimilars are available, including Fulphila, Udenyca, Ziextenzo, Nyvepria, and Fylnetra, at lower costs than brand Neulasta. This switch is a clinical decision your oncologist must make based on your specific treatment regimen.

Key Differences at a Glance

Zarxio: Most widely stocked, 4-day room temp stability, preferred by most insurers

Nivestym: Same indications as Zarxio, manufactured by Pfizer

Neupogen: Broadest indications (including radiation syndrome), highest cost, patient assistance available

Neulasta/pegfilgrastim: Longer-acting, once per cycle, not interchangeable without clinical decision

What to Tell Your Oncologist

If you cannot find Releuko in time for your scheduled dose, call your oncologist and say: "I am unable to fill my Releuko prescription. Can you write a new prescription for an available filgrastim alternative, or can your office administer it directly?" Time is critical with G-CSF therapy — do not wait more than 24 hours from when you're supposed to take the dose before escalating.

medfinder Can Help You Find the Right Option Fast

Whether you're looking for Releuko or an alternative, medfinder calls pharmacies near you to check which ones have your medication in stock. If Releuko isn't available, medfinder can also search for Zarxio, Nivestym, or Neupogen at nearby pharmacies after your oncologist writes the new prescription. For step-by-step guidance on locating Releuko, see our guide on how to find Releuko in stock near you.