Releuko Shortage: What Providers and Prescribers Need to Know in 2026

Releuko (filgrastim-ayow) was FDA-approved in February 2022 as the third filgrastim biosimilar, joining Zarxio (filgrastim-sndz) and Nivestym (filgrastim-aafi) in the U.S. market. For oncologists and hematologists managing patients who require G-CSF therapy, understanding Releuko's supply dynamics, formulary positioning, and therapeutic equivalence is critical to avoiding treatment disruptions in 2026.

Current Supply Status (2026)

As of 2026, Releuko does not appear on the FDA's Drug Shortage Database as an active national shortage. Amneal Pharmaceuticals (the marketing authorization holder) and Kashiv Biosciences (the manufacturer) have not publicly disclosed manufacturing disruptions. Domestic manufacturing provides some insulation from the international supply chain vulnerabilities that affect other injectable biologics. That said, prescribers should be aware that patient-level access issues remain common due to specialty distribution channels, formulary barriers, and prior authorization requirements — particularly for patients initiating therapy outside of established oncology clinic buy-and-bill relationships.

Formulary Positioning and Payer Landscape

Most major payers designate Zarxio (filgrastim-sndz) as the preferred filgrastim biosimilar due to its earlier market entry and established formulary positioning. UnitedHealthcare's Medicaid and commercial plan policies, for example, require a trial of Zarxio before approving Releuko under many formulary pathways. This means:

Prior authorization is typically required for Releuko on most commercial plans

Step therapy requirements may delay initiation by several days to weeks

Medicare Part B covers Releuko under HCPCS code Q5125 for buy-and-bill administration, with private payer reimbursement of approximately $0.435/mcg as of late 2025

Medicaid coverage varies by state — North Carolina Medicaid, for example, covers Releuko under HCPCS code J3590 for physician-administered drugs

Therapeutic Equivalence and Indication Differences

Releuko is indicated for:

Chemotherapy-induced febrile neutropenia prevention in non-myeloid malignancies

Neutrophil recovery after induction/consolidation chemotherapy in AML

Neutrophil recovery after myeloablative chemotherapy with BMT

PBPC mobilization for autologous transplant

Severe chronic neutropenia (congenital, cyclic, idiopathic)

Hematopoietic syndrome of acute radiation syndrome

Prescribers switching between filgrastim products should note: Zarxio and Nivestym are NOT approved for the radiation syndrome indication. Neupogen retains the broadest label. No filgrastim biosimilar is approved as interchangeable with Neupogen — each requires its own specific prescription, and pharmacy-level substitution is prohibited without prescriber authorization.

Clinical Protocols for Managing Availability Issues

Given the distribution and formulary complexity of filgrastim biosimilars, we recommend the following institutional approach:

Maintain formulary flexibility. Have standing orders or templates that allow prescribers to quickly switch between Releuko, Zarxio, and Nivestym when needed.

Pre-authorize where possible. Submit PAs before the first chemotherapy cycle begins rather than waiting until after. Retroactive PAs are rarely approved.

Verify buy-and-bill supply 5–7 days ahead. For clinic-administered Releuko, confirm your specialty distributor order 5–7 days before the patient's scheduled dose, particularly for high-volume periods like post-holiday or end-of-quarter.

Have alternative prescriptions ready. Proactively discuss with patients that a same-class switch may occur if supply is disrupted. Having the patient's consent reduces friction when a quick switch is needed.

How medfinder Can Support Your Patients

When patients are managing self-administered Releuko and run into availability issues, medfinder can help. medfinder calls pharmacies in the patient's area to identify which ones have the medication in stock, then texts the patient the results. This is particularly useful for patients with chronic neutropenia conditions who manage their own injections at home. Learn more at medfinder.com/providers. For a patient-facing version of this information, see our Releuko shortage patient guide.