Home Cosmetic Science Talk Formulating Accelerated Stability Parameters

  • Accelerated Stability Parameters

    Posted by MattTheChemist on March 29, 2021 at 2:20 pm

    What is everyones standard testing parameters for accelerated stability?
    I keep getting different answers from multiple sources.

    If you are setting the oven at 45C, should you set the humidity at ambient or an RH%? Some say only set the RH if you are testing for moisture permeable packaging. I always put the product in the oven in the final packaging it will be in, not the bench sample bottles, as I feel like in those bottles I could get false positives if the product darkens. I want to reflect real world scenarios.

    The IFSCC suggests these parameters below. When should and when shouldn’t RH be used in accelerated stability testing for the short 1-3 month period? Thank you! Just trying to clear up some confusion. 

    MattTheChemist replied 3 years, 2 months ago 4 Members · 4 Replies
  • 4 Replies
  • Pharma

    March 29, 2021 at 4:19 pm
    Pharma industry does test under different conditions, high as well as low humidity (water vapour can go either way), in the final packaging as well as before and under different conditions/setups.
    But then again, it all depends on the questions you want to have answered. If it’s about physical stability of an emulsion, you may as well just heat a ‘test tube’ and/or use a centrifuge. From my understanding, chemical stability isn’t really tested in cosmetics, just colour changes (and microbial growth). As long as you don’t have an anhydrous or highly hygroscopic product, water vapour permeation through the packaging won’t, in most cases, have a noticeable impact. However, air within the container (headspace) and therefore air permeability of the packaging, the product/air interface, and the depth (max distance from interface) of the product will. Depending on the product you test, light will also be a factor you’d have to consider but you probably won’t test for that with a standard oven.
    Bottom line is: Don’t ask what others do/think and duplicate but ask what YOU want to see/prove and plan your tests accordingly.
  • OldPerry

    March 30, 2021 at 12:00 am

    Typically, humidity doesn’t matter for cosmetic packaging but try to keep it consistent at each temperature.

  • PhilGeis

    March 30, 2021 at 9:48 am

    Agree with your comment Matt re. in actual package.  Do follow up rapid aging with real time data and decide now what you’ll do if they do not confirm.

    I would stick generally to established protocol - both for liability and compliance if you’re making cosmetic/OTC drugs.

  • MattTheChemist

    March 30, 2021 at 11:10 pm

    @perry @PhilGeis @Pharma thank you so much! I have also reached out to a third-party testing lab for parameters. Real time stability has held up well, it is just accelerated where darkening is occurring. Pharma has been kind to assist in troubleshooting. Again, thank you!

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