Medical Device Shelf Life/Aging Studies
Medical device manufacturers wishing to gather data on the shelf life of their products may subject their devices to long-term stability studies or accelerated aging studies. There are many different endpoints that can be used to assess the shelf life of a medical device, including sterility or package integrity, so it is important that endpoints and test methodology are decided upon before testing is begun.
For reusable devices, sterilization cycle testing may also be appropriate. This involves subjecting a device to many (for example 50 or 100) cycles of a sterilization or disinfection process to determine whether the device maintains functionality over time.
The GMP microbiological labs at Pacific BioLabs can provide clients with temperature and humidity controlled chambers for storing samples for various types of medical device shelf life and aging studies on both products and packaging. All chambers are monitored 24/7 by the Rees or Visalia environmental monitoring system.
Available Medical Device Accelerated Aging Chamber Conditions
- 25C / 60% Relative Humidity
- 40C / 75% Relative Humidity
- Other non-standard temperatures and relative humidities
The accelerated aging technique is based on the assumption that the chemical reactions involved in the deterioration of materials follow the Arrhenius reaction rate function. This function states that rises in temperature of 10°C will double the rate of a chemical reaction. This function is expressed as a Q10 factor – i.e. the ratio of the rate of a reaction at two temperatures 10°C apart. If the rate of the reaction is doubled then Q10 = 2. This is the most common approach used to perform accelerated aging of medical devices.
The elevated temperature condition typically used at Pacific Biolabs for the accelerated aging of medical device packages is 55°C. If Q10 = 2 and the accelerated aging condition is 55°C, or 30°C over an ambient temperature of 25°C, then the aging factor is 2^3 which equal 8. One year, or 365 days divided by 8 = 45.6 days. Therefore, 45.6 days at 55°C is equivalent to one year at an ambient temperature of 25°C. Unless otherwise specified by the client, to simulate each year of aging, PBL stores samples at 55°C with ambient humidity for 46 days.
While humidity is not a factor in the accelerated aging process, it is an option to use humidity. One approach is to rotate packages through both high and low humidity conditions at 55°C (Samples can start in either low or high humidity). Another option is to maintain at freezing temperatures for 24 hours in between high and low humidity. Humidity and freezing challenges are not required but may be included as additional stresses to simulate worst case conditions.