Mounjaro (tirzepatide) is an injectable medication primarily prescribed to manage blood sugar levels in adults with type 2 diabetes. It also aids in weight management. Proper storage conditions are important to ensure its effectiveness and safety, especially regarding refrigeration.
Unrefrigerated Stability Period
Unopened Mounjaro pens can be kept outside of refrigeration for a limited time. An unopened pen may remain at room temperature for up to 21 days, provided the temperature does not exceed 86°F (30°C). Once removed from the refrigerator, this 21-day period begins, even if the pen is later returned to the cold. If the medication is not used within this 21-day window, it should be safely discarded.
For pens that have been opened and are currently in use, some guidance indicates they can be stored at room temperature, again not exceeding 86°F (30°C), for up to 30 days. However, exposure to direct heat or bright light can compromise the medication and shorten its viability. Freezing Mounjaro at any point renders it unusable, even if it thaws, as the active ingredients can be irreversibly damaged.
Why Specific Temperatures Matter
Tirzepatide, Mounjaro’s active ingredient, is a peptide. Peptides are sensitive to environmental factors, especially temperature fluctuations. Exposure to temperatures outside the recommended range can degrade the medication’s molecular structure.
When Mounjaro is subjected to excessive heat, the peptide bonds within tirzepatide can break down, potentially reducing its potency and effectiveness. Conversely, freezing the medication can cause irreversible damage to its delicate peptide structure, altering its composition and making it unsafe for use. Maintaining the correct temperature ensures the medication remains stable, effective, and safe. Protection from light is also important, as light exposure can contribute to the degradation process.
Comprehensive Storage Guidelines
Unopened Mounjaro pens should be stored in a refrigerator between 36°F and 46°F (2°C and 8°C). Keep pens in their original carton to shield them from light, which can degrade the medication. Avoid storing Mounjaro in the refrigerator door, as temperatures can fluctuate more frequently there.
Once a Mounjaro pen has been opened and is in use, it offers more flexibility in storage. It can either be kept at room temperature, not exceeding 86°F (30°C), for up to 30 days, or it can be returned to the refrigerator within the specified temperature range. Regardless of storage location, a pen should be discarded 30 days after its first use, or after all four weekly doses have been administered, whichever comes first. During travel, Mounjaro should be transported in a cool bag with ice packs, ensuring it does not freeze, and ideally carried in hand luggage to maintain temperature control.
When to Discard Mounjaro
Know when Mounjaro should no longer be used to ensure safety and efficacy. The medication must be discarded if it has been stored unrefrigerated for longer than the specified 21-day period for unopened pens, or 30 days for pens in use. Any Mounjaro pen that has been exposed to freezing temperatures should also be immediately discarded, as freezing damages the medication beyond repair.
Mounjaro should also be discarded if it has been exposed to temperatures significantly above the recommended range, such as being left in a hot car. Before each use, visually inspect the solution; it should be clear and colorless, free from cloudiness, discoloration, or any particles. If the medication’s expiration date has passed, it is no longer effective or safe and must be discarded. Used Mounjaro pens, including needles, should be disposed of immediately in an FDA-cleared sharps container to prevent injury and contamination, following local guidelines.