By Noel Gibbons, BSc (Hons)
Recently, Medical Packaging Innovation came to me with the following question regarding aging and climatisation:
Medical Packaging Innovation: The goal of testing is to simulate real life exposure and check the fitness of the device packaging. The usual recommendation is to not combine aging testing with transport testing because in case of failures it cannot be concluded clearly whether the aging or the transport caused the failure. However, in real life, devices are stored and are then distributed and exposed to transport strains.
Would it make sense to recommend a combination of accelerated aging with physical transport testing only while excluding climatisation in order to avoid exaggerated (double) temperature aging? Climatisation testing can include 3 different levels: isn't that a kind of aging, too? Would one of those levels be similar to the effects of a 5 years accelerated aging?
Also, would it make sense to expose 50 packages under accelerated aging conditions then test integrity on 25 and -- if these pass -- take the residual 25 and make a transport testing? Such approach -- if reasonable -- puts the transport testing timing after the accelerated aging and before commercial phase, correct?
The ageing and transportation testing standards were separated with the update to ASTM F1980 in 2007 when all references to transportation were removed. The reason that they were separated is that these are two very different processes, are not dependent on each other, and have similar but different outcomes.
The transportation simulation testing looks at the ability of the primary and secondary packaging to protect the sterile product, sterile barrier, and the functionality of the product.
Accelerated and real-time ageing look at the ability of the primary packaging to retain its sterile barrier properties, and should also look at the functionality of the product.
The typical life of a product is as follows:
- it is manufactured
- it is tested
- it is packaged
- it is shipped to distribution, (normally the longest shipment duration)
- it is shipped to point of sale / end user (normally the shortest shipment duration)
Therefore, while both ageing and transportation testing look at the retention of sterility, they both also look at two very different processes. The transportation testing proves the product packaging retains its sterile barrier throughout the rigors of the shipping process using integrity and strength testing, while the accelerated ageing (and real-time ageing) prove that the product packaging retains its sterile barrier throughout the ageing process using integrity and strength testing.
After the distribution simulation and ageing studies have been carried out, the sterile barrier should be evaluated, and the seal strengths assessed and compared to the levels achieved during the initial packaging introduction / validation.
Based on the second question about using a combination of accelerated aging with physical transport testing, yes, you could do this, but based on the above, it would not provide any additional information once the seals and packaging retained their sterile barriers and had not reduced in any significant way.
There is also the cost rationale that needs to be taken into account. If, for example, you were to age a product for the equivalent of five years, then a transportation test is best. If the transportation test fails for any reason all, the data from the ageing could be called into question and all the testing would have to be repeated -- not just the part that failed.
In relation to the conditioning cycle, if you only do one temperature, like the accelerated ageing temperature, and the test passes, you have no information on the cold temperatures or different levels of relative humidity, which have different effects on packaging and products.
In my opinion, distribution and ageing studies should be carried out separately so as on to avoid over-stressing the packaging and possibly causing problems that would not normally be there in the packaging.
Once you have carried out transportation testing on the packaged products in their worst case configurations -- lowest, highest, and nominal sealing parameters along with minimum, maximum, and nominal shipping configurations -- you have proven that the packaging is capable of being shipped without issue to the sterile integrity or strength of the sterile barrier.
Integrity and strength testing after ageing the product and packaging gives you the proof that the product is viable and the packaging can remain sterile up to its shelf life.
This process gives results that are easily repeatable in a timely manner, while being comparable all the way back to when the packaging was introduced and tested during the OQ process.