Medications and Stability
The welcome news of potential COVID-19 vaccines has included information about storage requirements, bringing to the forefront the critical nature of temperature and its effect on the potency of medicine. While the news is evolving almost daily, in late November, we learned that one COVID vaccine has “relatively simple storage requirements,” but will likely need to be refrigerated, another can be stored up to 30 days at the temperature of a normal refrigerator, and another up to five days in a conventional refrigerator, a special cooler for up to 15 days, and beyond that “ultracold storage.”
The Centers for Disease Control explains: “Vaccines must be stored properly from the time they are manufactured until they are administered. Potency is reduced every time a vaccine is exposed to an improper condition. This includes overexposure to heat, cold, or light at any step in the cold chain. Once lost, potency cannot be restored.”(1)
Storage temperatures are critical for potency not only for vaccines, but for all medicines. Many commonly-used medications must be refrigerated. For these, refrigeration maintains potency. Others must be stored at room temperature and cannot be refrigerated. The antibiotic moxifloxacin is an example. If moxifloxacin is refrigerated, it precipitates, forming a solid.
In addition to storage requirements, healthcare providers must also pay attention to Beyond Use Dates (BUDs) and expiration dates. While the two terms are related, they are used for different kinds of products.
BUD identifies the time by which a compounded preparation, “must be used before it is at risk for chemical degradation, contamination, and permeability of packaging. The BUD serves to alert pharmacists and caregivers to the time after which a compounded sterile product cannot be administered.”(2)
An expiration date is established by a product manufacturer, in accordance with FDA regulations. According to the FDA, “drug expiration dates reflect the time period during which the product is known to remain stable, which means it retains its strength, quality, and purity, when it is stored according to its labeled storage conditions.”(3) Depending on the formulation, storage conditions could be room temperature, refrigerated, or frozen storage. It is important to take storage conditions into account when planning transport, inventory, and daily utilization of medicines.
(1) Centers for Disease Control and Prevention, Vaccine Storage and Handling, https://www.cdc.gov/
(2) Read, K., Gans, S. M.D. (reviewer) verywellmind, Beyond Use and Expiration Date Differences, https://www.verywellmind.com/
(3) Food and Drug Administration, Expiration Dates: Questions and Answers, https://www.fda.gov/