Stability Testing Simplified

Following Noel Gibbons's blog on Ageing & Climatisation, I thought I would offer some of my thoughts on aging and stability testing.

  • Are package stability samples taking up too much storage space?
  • Can you get enough medical devices far enough ahead of time to do stability testing?
  • Do I performance-test the package system before or after aging?
  • What will be the worst-case scenario?
Hal Miller

Here is another approach to consider:
If you do not have to be concerned with environmental conditions on you device, simply perform stability or aging tests with the package materials and seals that you intend to use.

The intent of stability or aging testing is to determine whether your materials and seals will deteriorate over time such that sterile package integrity is maintained. Physical material properties such as tear, puncture, stress cracking, impact resistance and seal strength, and microbial barrier properties will be the indicators of any deterioration and to what extent, if any. Most common sterile device packaging materials used today demonstrate very little deterioration of physical properties, if any, as a result of sterilization processes. Therefore, samples of sealed materials are all that is needed for stability studies.

Well, don’t you need to construct and seal the package to evaluate the seals, you might say? A seal is a seal is a seal. The seal of mated materials will act the same regardless of the sealing process. Seal strength plots over time will indicate the trend or slope of the seal strength. If the seal strength at the end of the aging period is higher than your documented minimum seal strength for the package and process, all is fine.

Because actual packages and devices are not essential to demonstrate package stability over time, many sterile packaging material manufacturers have this data for you. Eastman has data for PETG 6763, DuPont has data readily available for all grades of Tyvek, and many manufacturers of films and heat seal coatings have five-year real-time and accelerated data for their materials. This data then becomes part of the device history file to document stability. All you need to do is ask.

This approach is especially beneficial when implementing new materials or heat seal coatings for your package. Remember, compliance with ISO 11607-1 and -2 is nothing more than qualifying your materials, validating the process, and testing the package. Keep packaging off the critical path!

Stay relevant as a medical device packaging engineer

Hal Miller, President, PACE Solutions

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