The FDA requires demonstration that a medical device sterile barrier system (SBS) will maintain its integrity and sterility when stored over time. Accelerated aging is an artificial procedure for establishing the shelf life of a product in an expedited manner. A product can be released to market based upon successful accelerated aging test results that simulated the period claimed for product expiration date. Accelerated aging is recognized by regulatory bodies as a conservative estimate of shelf life but is only accepted until the testing is performed under real-time aging conditions.
Glass Transition Temperature
Understanding the material glass transition temperatures is key to having a successful aging study. Much like cooking, the higher the temperature the greater the risk of failure. There are plenty of things to consider when setting up aging studies:
- materials of construction
- sealing process settings
- ambient conditions
… to name a few.
When calculating the aging duration using the Arrhenius equation, it is important to input a reasonable aging temperature setpoint. The lower the temperature, the longer the duration, this is the lowest risk approach.
AAF=Q₁₀ ⁽ᵀᴬᴬ⁻ᵀᴿᵀ⁾/¹⁰ where;
- Q₁₀ = an aging factor for 10°C increase or decrease in temperature
- TAA = accelerated aging temperature (°C)
- TRT = ambient temperature (°C)
Failures often occur when we use a high temperature to save on time. Once a materials glass transition temperature is reached it will start to warp, leading to failures after months of aging. Using an adequate aging temperature is key to a successful stability study. Typical aging temperatures range between 45°C – 60°C. It is important to review the materials data sheet to become familiar with their material characteristics in order to not over age the test samples.
These are only some of the key considerations to take into account when planning any aging study. Planning for success after months of aging will save your business time and money, launching your product on-time, each time.