Provider Briefing: The Zarxio Shortage in 2026

The ongoing shortage of filgrastim products — including Zarxio (filgrastim-sndz) — continues to affect oncology practices, hospitals, and patients nationwide. For providers managing patients on myelosuppressive chemotherapy regimens, this shortage introduces real clinical risk: delayed G-CSF administration increases the incidence of febrile neutropenia, treatment interruptions, and potentially avoidable hospitalizations.

This briefing provides a concise overview of where the Zarxio shortage stands in 2026, what's driving it, how it affects prescribing decisions, and what tools are available to help your patients access their medication.

Shortage Timeline

Filgrastim products have been on the FDA's drug shortage list intermittently since 2022. Here's a high-level timeline:

• 2022: Initial reports of intermittent filgrastim supply disruptions, primarily affecting smaller distributors and retail pharmacies
• 2023: Shortage escalates as manufacturing issues at multiple producers coincide with increased post-pandemic chemotherapy volumes. FDA formally lists filgrastim on the drug shortage database
• 2024: Supply improves modestly as Sandoz and other manufacturers increase production. However, distribution remains uneven, with rural and smaller practice sites disproportionately affected
• 2025: Additional biosimilar entrants help stabilize supply in some markets, but spot shortages persist nationally
• 2026 (current): Availability is inconsistent but improving. Specialty pharmacy channels generally have more reliable stock than retail chains. Some health systems report near-normal supply while others continue to face periodic gaps

Prescribing Implications

The shortage has several practical implications for prescribers:

Treatment Timing

G-CSF medications like Zarxio are typically initiated 24 hours post-chemotherapy and continued until ANC recovery. When patients cannot fill their prescription in time, the window for optimal G-CSF support narrows. Delayed initiation has been associated with increased rates of febrile neutropenia and dose-delayed chemotherapy cycles.

Formulary Flexibility

Most health systems and insurance plans have added multiple G-CSF products to their formularies in response to the shortage. If your formulary lists Zarxio as the preferred agent but it's unavailable, switching to another filgrastim product (Neupogen, Granix) or a pegfilgrastim product (Neulasta, Udenyca, Fylnetra) is clinically appropriate for most patients.

Key considerations when switching:

• Short-acting → long-acting: Transitioning from daily filgrastim to once-per-cycle pegfilgrastim changes the dosing paradigm. Ensure patients understand the single-injection schedule
• Prior authorization: Switching products may trigger new PA requirements. Consider having your practice's PA team prepare alternative requests proactively
• Patient education: If patients have been trained on Zarxio self-injection, they'll need updated instructions for any new product, particularly on-body injectors like the Neulasta Onpro device

Documentation

Document the clinical rationale for any product switch in the patient's chart. Note the shortage as the reason for the change — this supports insurance appeals and maintains continuity of care documentation.

Current Availability Picture

Zarxio availability in 2026 varies significantly by distribution channel:

• Specialty pharmacies: Generally the most reliable source. Many oncology-focused specialty pharmacies maintain dedicated G-CSF inventory
• Hospital/health system pharmacies: Availability depends on the system's wholesaler agreements and group purchasing organization (GPO) contracts. Some systems report adequate supply; others face intermittent gaps
• Retail chain pharmacies: Least reliable for Zarxio during shortage periods. Large chains serve high patient volumes and may deplete stock quickly
• 340B entities: Covered entities using 340B pricing may experience different availability patterns based on their contract pharmacy networks

Cost and Access Considerations

Zarxio remains one of the more affordable G-CSF options, priced 40% to 50% below brand Neupogen:

• Zarxio cash price: $250–$450 per 480 mcg syringe
• Neupogen cash price: $500–$900 per syringe
• Pegfilgrastim (Neulasta) cash price: $5,000–$8,000 per injection
• Pegfilgrastim biosimilars (Udenyca, etc.): $3,000–$5,000 per injection

For uninsured or underinsured patients, Sandoz offers support through Sandoz One Source, and the Novartis Patient Assistance Foundation provides free medication to qualifying patients. NeedyMeds and RxAssist also maintain current program listings.

For patients struggling with cost, refer them to our resource on saving money on Zarxio, or see the provider-focused guide on helping patients save on Zarxio.

Tools and Resources for Providers

Medfinder for Providers

Medfinder offers real-time pharmacy inventory data that helps you and your patients identify which pharmacies currently have Zarxio in stock. This is particularly valuable when your practice's usual pharmacy or distributor is out of supply.

You can direct patients to medfinder.com/providers or use it yourself to quickly check local availability before writing or transferring a prescription.

FDA Drug Shortage Database

The FDA maintains an updated list of drugs currently in shortage, including filgrastim products. Check accessdata.fda.gov/scripts/drugshortages for the most current status and estimated resolution dates.

ASHP Drug Shortage Resource Center

The American Society of Health-System Pharmacists (ASHP) provides detailed shortage information, clinical guidance, and alternative recommendations for managing G-CSF shortages.

Specialty Pharmacy Networks

If your practice doesn't already have a relationship with an oncology-focused specialty pharmacy, now is a good time to establish one. Specialty pharmacies often have more reliable access to shortage-affected medications and can coordinate directly with your prescribing team.

Looking Ahead

The outlook for Zarxio supply is cautiously optimistic:

• Additional biosimilar approvals are expanding the total G-CSF manufacturing base
• Manufacturer investments in biologic production capacity are underway at several facilities globally
• FDA initiatives to streamline biosimilar approvals and improve supply chain transparency may help prevent future shortages
• Health system preparedness has improved, with more institutions maintaining safety stock and multi-product formularies

However, biologic drug shortages are inherently unpredictable. Continued vigilance and proactive planning remain essential.

Final Thoughts

The Zarxio shortage is a clinical and logistical challenge that requires providers to be adaptive. Maintain formulary flexibility, educate patients about alternatives, leverage real-time tools like Medfinder, and document shortage-related treatment changes carefully.

Your patients are counting on you to help them navigate this difficult situation. By staying informed and proactive, you can minimize treatment delays and keep your patients on track — even when supply chains fall short.

For a practical workflow guide, see our companion article: How to help your patients find Zarxio in stock.