Hello everyone,
we are performing accelerated aging tests for various medical devices at 45°C (coming from 25°C).
When performing real time aging, we have a question. At which temperature do I have to store the material, when the pouch labels 25°C max? Can we conclude that if the product is stable after the accelerated aging and the product is stable at 20°C room temperature we can claim 25°C on the pouch?
Or do we have to test the product at the maximum temperature that is claimed? Meaning storing at 25°C for 3 years of claimed shelf life.
Probably an easy question, but we are quit stuck in our discussions. Any hint is appreciated.
Thank you!
Hi,
Actually not an easy question at all. You'll be surprised at how confused industry and regulators are WRT accelerated ageing, in general, though most won't admit it. If we scratch the surface of common practice and beliefs, it's shocking how much superstition and "degenerated-science" are embedded in this area (I'm not referring to you but to industry in general). I've posted about it quite a lot in Elsmar, and thinking of writing a more comprehensive article on the topic, but it seems like I'm barking and industry just keeps going, so maybe it's pointless. I think I understand why they do it - proper, engineering/science-based shelf life ("stability") validation takes thinking, time, work and money - sometimes a lot of one (or more) of these - and why bother if regulators are happy with the current (mostly meaningless) rituals. Field failures (complaints) are not often investigated properly so not many times ageing failures are properly attributed to inadequate design (device, packaging, storage conditions specification) and inadequate life validation. And so, the problem is not visible and there's little drive to improve.
Okay, back to your question -
You've actually asked more than one question. I think it'll be more effective to review the entire thought process. Let's start with your goals:
What are the environmental requirements of your device? Do you have reason to believe it will deteriorate at >25C?
Why put 25C max on the label? This is not a realistic expectation for uncontrolled shipping and storage, and under controlled conditions would place a serious burden throughout the supply chain, including the end user.
You need to understand the necessities of your device and its packaging (sterile barrier?), and also the typical and extreme environmental profile the devices will be exposed to throughout distribution and final storage.
BTW, don't forget to consider the lower end of the temperature scale too.
For real-time ageing, store in typical expected conditions. If there's more than one "typical" scenario (e.g. warm countries vs. cold ones), maybe you need more than one test group.
For accelerated ageing, you normally pick a "room temperature" baseline from which you claculate. I've seen 22C, 23C and 25C being used, and since all this business is not based on solid engineering/science, they're all equally valid. And why is it so shaky? because almost no-one bothers to look into the actual (physics) ageing mechanisms that deteriorate the device or the packaging, whether they are time-related, whether they are temperature (or humidity, or whatever) related, and whether they can be accelerated at all, and in what way.