Why Is Releuko So Hard to Find? [Explained for 2026]

If you or a loved one has been prescribed Releuko (filgrastim-ayow) and found it difficult to locate at a pharmacy, you are not alone. Releuko is a specialty oncology injectable, and its availability works very differently from a typical oral medication you might pick up at your corner drugstore. Understanding why Releuko can be hard to find — and what you can do about it — can save you time and reduce stress during an already difficult period of cancer treatment.

What Is Releuko and Why Does It Matter?

Releuko (filgrastim-ayow) is a biosimilar to Neupogen (filgrastim), the original granulocyte colony-stimulating factor (G-CSF) medication approved by the FDA in 1991. It was developed by Kashiv Biosciences and Amneal Pharmaceuticals and received FDA approval on February 25, 2022, making it the third filgrastim biosimilar on the market.

Releuko is used to prevent or treat neutropenia — a dangerous drop in white blood cells that commonly occurs as a side effect of chemotherapy. Without it, cancer patients face a significantly higher risk of life-threatening infections. In short, Releuko is not a medication patients can simply skip or delay — it is a critical part of cancer care.

Why Is Releuko Hard to Find at Regular Pharmacies?

The biggest reason Releuko is difficult to find is that it is a specialty biologic injectable, not a standard retail pharmacy product. Here are the main factors that affect its availability:

1. It Requires Cold Storage and Specialized Handling

Releuko must be refrigerated at 2°C to 8°C (36°F to 46°F) and protected from light. It should never be frozen, and once removed from refrigeration, it can only be held at room temperature for a maximum of 24 hours. This cold-chain requirement means that most retail pharmacy chains do not routinely stock it on shelves. Only specialty pharmacies and oncology clinics with proper storage infrastructure typically carry it.

2. It Is Distributed Through Specialty and Buy-and-Bill Channels

Most cancer patients receive Releuko through one of two channels. The first is the "buy-and-bill" model, where your oncologist's office or infusion center purchases the medication directly from a specialty distributor and administers it to you during your visit. The second is a specialty pharmacy that ships directly to your home or clinic. Neither of these channels routes through the standard retail pharmacy distribution network, which is why you won't find it at most CVS, Walgreens, or Rite Aid locations.

3. Insurance and Formulary Restrictions Complicate Access

Releuko is one of three filgrastim biosimilars currently available. Many insurance plans have a preferred formulary product — often Zarxio (filgrastim-sndz) — and may require step therapy, meaning you must try the preferred product first before they will cover Releuko. This creates delays even when your oncologist specifically prescribes Releuko. Prior authorization is commonly required for specialty biologics like Releuko, which can add days or weeks to the process.

4. No Automatic Pharmacy Substitution Is Allowed

Unlike generic medications, Releuko cannot be automatically substituted at the pharmacy counter for another filgrastim product. Your prescriber must specifically order Releuko by name. If the pharmacy does not have it, they cannot simply swap in Zarxio or Nivestym without going back to your doctor for a new prescription. This rigidity in the system means a stock gap at one pharmacy can cause significant delays.

5. Supply Is Concentrated in Oncology Networks

Because Releuko is dispensed primarily through oncology clinics and specialty pharmacies, patients who need to fill it at a retail pharmacy face a much harder time. Specialty distributors such as AmerisourceBergen Specialty Group, McKesson Specialty, and Cardinal Health Specialty prioritize oncology clinics and hospital systems, not retail chains. This means a patient calling their neighborhood pharmacy may be told the drug is unavailable even when adequate national supply exists.

Is Releuko Currently in a Shortage?

As of 2026, Releuko is not listed on the FDA's official Drug Shortage Database as an active national shortage. However, this does not mean it is easy to find. The difference between a formal shortage and a distribution or access challenge can feel identical to the patient standing at a pharmacy counter. Localized availability issues, specialty distribution bottlenecks, and insurance hurdles all contribute to real-world difficulty finding the drug even when the national supply is technically adequate.

What Should You Do If You Can't Find Releuko?

Here are the most effective steps to take if you're having trouble locating Releuko:

Contact your oncologist's office immediately. They often have direct access to specialty distributors and may already have the medication on hand for buy-and-bill administration.

Ask for a specialty pharmacy referral. Specialty pharmacies like Accredo, CVS Specialty, and Walgreens Specialty have the infrastructure to stock and ship Releuko.

Check if another filgrastim product is an option. Ask your oncologist whether Zarxio, Nivestym, or Neupogen would work for your situation while Releuko availability is resolved.

Use medfinder. medfinder calls pharmacies near you to find which ones can fill your Releuko prescription, so you don't have to spend hours on hold.

How medfinder Helps Patients Find Releuko

medfinder is a service that calls pharmacies near you to check which ones have your medication in stock and can fill your prescription. Instead of spending your afternoon on hold with pharmacy after pharmacy, you simply provide your medication, dosage, and location, and medfinder does the calling for you. Results are texted directly to your phone. For a specialty medication like Releuko where retail stocking is inconsistent, this kind of targeted search can make all the difference. Learn more about finding Releuko at medfinder.com.

The Bottom Line

Releuko is hard to find not because of a national crisis, but because of how specialty oncology biologics move through the healthcare system. Cold-chain requirements, specialty-only distribution, insurance step therapy, and the inability to auto-substitute all combine to make it a challenging medication to locate at a standard pharmacy. Your best bet is to work closely with your oncology team, explore specialty pharmacy options, and use a service like medfinder to do the legwork. For more on current availability, read our Releuko shortage update for 2026.