Does ARCALYST Need to be Refrigerated? A Guide to Proper Storage

October 9, 2025 •

4 min read

According to the U.S. Food and Drug Administration (FDA) prescribing information, the lyophilized powder form of ARCALYST (rilonacept) must be stored in a refrigerator. The short answer to 'Does ARCALYST need to be refrigerated?' is a definite 'yes' for the unmixed medication, with strict temperature controls to maintain its therapeutic efficacy and safety.

Quick Summary

The unmixed ARCALYST powder must be refrigerated at 36°F to 46°F (2°C to 8°C) and protected from light before use. After it is reconstituted with sterile water, the solution can be stored at room temperature but must be used within three hours and protected from light.

Key Points

Pre-mixing Refrigeration: The lyophilized ARCALYST powder must be stored refrigerated between 36°F and 46°F (2°C and 8°C) before reconstitution.
Post-mixing Time Limit: After mixing with sterile water, the solution can be kept at room temperature but must be used within three hours.
Light Protection: Both the unmixed powder and the reconstituted solution must be protected from light.
Discarding Unused Medicine: Any unused portions of the mixed ARCALYST solution must be discarded, as it contains no preservatives.
Temperature Excursions: If the medication is received warm or left out of the refrigerator, contact your healthcare provider or patient support immediately for guidance.

The Importance of Refrigeration for ARCALYST

ARCALYST, a potent medication containing the active ingredient rilonacept, is a biologic drug. Biologics are medicines made from living organisms and are sensitive to temperature and light. Proper storage is not just a suggestion; it is a critical requirement to ensure the drug's stability, potency, and safety. The specified refrigeration temperature is vital because it prevents the delicate protein structure of rilonacept from degrading. Once the protein is damaged by heat, it may become ineffective, and its therapeutic effects could be lost. For this reason, patients must meticulously follow the storage instructions provided by their healthcare providers and the manufacturer.

Storage Guidelines: Before and After Reconstitution

The storage protocol for ARCALYST is divided into two distinct phases: before and after the powder is reconstituted into a liquid solution. Each phase has specific requirements that must be followed.

Before Reconstitution (Unmixed Powder)

Before you mix ARCALYST with sterile water for injection, it is supplied as a sterile, white to off-white, lyophilized powder in a single-use glass vial. The storage rules for this powder are precise:

Refrigerate: Store the vial in a refrigerator at a temperature between 36°F and 46°F (2°C and 8°C).
Protect from Light: Keep the vial inside its original carton to protect it from light until it is time to prepare your dose.
Expiration Date: Use the medication before the expiration date stamped on the label and carton.
Do Not Freeze: The medication should not be frozen.

After Reconstitution (Mixed Solution)

Once the ARCALYST powder has been mixed with sterile water, the storage rules change dramatically:

Room Temperature: The reconstituted solution may be kept at room temperature.
Limited Time: The solution must be used within three hours of mixing.
Protect from Light: The mixed solution should also be protected from light.
Discard Unused Portions: Since ARCALYST contains no preservatives, any unused portion of the mixed solution must be discarded after the three-hour window.

What to Do If ARCALYST is Not Refrigerated

If the lyophilized ARCALYST powder is left unrefrigerated, its stability and effectiveness may be compromised. If you receive a package that feels warm or the temperature monitor inside the shipping container has been activated, you should not use the product. The correct course of action is to contact your Patient Access Lead or pharmacist immediately for guidance. Using a compromised medication can lead to reduced efficacy or other issues.

Comparison of Storage for Different Biologics

Many biologic medications have unique storage requirements. Comparing ARCALYST to another biologic, such as Enbrel (etanercept), highlights the importance of checking specific instructions for each drug.


Feature	ARCALYST (rilonacept)	Enbrel (etanercept)
Unmixed Form	Lyophilized powder in a vial	Prefilled syringe, prefilled autoinjector
Pre-Use Storage	Store refrigerated at 36°F–46°F (2°C–8°C)	Store refrigerated at 36°F–46°F (2°C–8°C)
Storage at Room Temp (Unmixed)	No, must remain refrigerated	Up to 14 days, protected from light
Post-Mixing Storage	Use within 3 hours at room temperature	Not applicable (comes pre-filled)
Light Protection	Store in original carton to protect from light	Keep in original packaging

Best Practices for ARCALYST Storage and Handling

Confirm Temperatures: Before storing your ARCALYST, ensure your refrigerator is set to the correct temperature range. Use a thermometer to verify if necessary.
Inspect Upon Arrival: Check your package immediately upon delivery. If it feels warm or if a temperature monitor is flagged, contact your pharmacy or patient support program before using it.
Keep in Original Packaging: Always keep the unreconstituted vial in its original carton to protect it from light exposure, which can damage the medication.
Adhere to Mixing Protocol: Only mix the powder when you are ready to use it for an injection. Never mix it in advance.
Follow the 3-Hour Rule: After mixing, the clock starts. You have a maximum of three hours to use the solution before it must be discarded.
Safe Disposal: Properly dispose of any expired, unused, or compromised ARCALYST. Follow local guidelines for sharps and medication disposal.

Conclusion

For patients relying on ARCALYST, understanding and adhering to the specific storage instructions is non-negotiable. The medication's lyophilized powder form requires consistent refrigeration at 36°F to 46°F (2°C to 8°C) and protection from light to maintain its integrity. After reconstitution, the short three-hour window for use at room temperature underscores the importance of proper timing and preparation. Any deviation from these strict guidelines can affect the medication's therapeutic benefit. Always contact your healthcare provider or pharmacist if you have concerns about the storage or handling of your ARCALYST supply. For more detailed instructions, you can refer to the official FDA package insert.

Reference

For comprehensive guidance on ARCALYST, the official U.S. Food and Drug Administration prescribing information is a key resource. You can access it directly via the following link: Arcalyst (rilonacept) Label - accessdata.fda.gov.

Frequently Asked Questions

The unmixed ARCALYST vial must be stored in the refrigerator at a temperature between 36°F and 46°F (2°C and 8°C).

No, the lyophilized ARCALYST powder cannot be left unrefrigerated. The medication must be kept in the refrigerator until you are ready to mix and use it.

After mixing with sterile water, the ARCALYST solution can be stored at room temperature but must be used within three hours. Any unused portion must be discarded after this time.

If your ARCALYST has been left unrefrigerated or if the package feels warm upon arrival, you should not use it. Contact your healthcare provider or patient access team for guidance and to determine if it needs to be replaced.

Yes, ARCALYST must be protected from light. The unreconstituted vial should be kept in its original carton, and the mixed solution should also be kept away from light.

No, once the medication has been mixed and brought to room temperature, it should be used within three hours or discarded. It should not be returned to the refrigerator.

If your reconstituted ARCALYST solution appears discolored, cloudy, or contains particles, do not use it. You should discard it and contact your pharmacist or healthcare provider for a replacement.