About Stability Testing

Hi there! 

I really need some help on cosmetic accelerated stability testing. 

I know that there ain't no official guideline about it, so sometimes you can get a little lost/confused when you truly have to conduct a stability testing. I already studied some guidelines, like the IFSCC Monograph, the Colipa guideline, and ANVISA stability guide (Brazil), but I'm still confused about some topics. I know that there's a lot of cosmetic systems, and they are all complexes, but I'm talking specifically about the stability of emulsions and shampoos/liquid soaps, since I normally don't formulate make-up products. 

So, my main question is: how do you truly 'predict' the expiration date of a cosmetic formulation? If my formulation (a emulsion) remains stable at 45ºC for three months (in an incubator) how long can I predict at normal conditions? 2 years? 3 years? What is the 'rule' that you guys follow?

The second one is: how can I conduct a 'in real time' stability testing? I mean, when the product is already being sold at the market. What is the periodicity of the readings?

Thanks in advande! :smile:

Best regards, 

Comments

  • PerryPerry Administrator, Professional Chemist
    There's no real specific rule, just industry standards, or at least what the big companies do.

    Roughly, sample stored at 45C for 12 weeks = 1 year stability at Room Temperature. 

    This is vaguely based on the Arrhenius equation which predicts chemical reaction rates of systems. Reaction rates double every 10C.

    So if RT = 25C and lasts 1 year
    the same system at 35 C would last 6 months
    the same system at 45 C would last 3 months

    Of course, this is just a rough guideline because you don't really know what would be causing something to become unstable. If it is microbial contamination then these numbers wouldn't really hold up.  But it's a rough guess.

    I think the guideline for longer stability is 1 year at 45C = 3 year RT.  However, big companies don't expect cosmetic products to last more than 1 year.

    See this post on cosmetic stability testing
     


  • Thank you so much, @Perry !
  • PhilGeisPhilGeis Member, Professional formulator
    Consider 1 and 3 months at 45C as relevant to 1 and 2 year exp. dates.  Wouldn't presume anything in rapid aging predicts 3 years.
    Get 1,2 and 3 year real time data.  1 and 2 confirm rapid aging and 3 is instructive to preservative systems even if product no longer on market.

    Also see how US FDA sees stability testing of OTC drugs.

    https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/inspection-technical-guides/expiration-dating-and-stability-testing-human-drug-products
  • We do the standard Stability Test at 45ºC for three months (in an incubator). Then our QC Manager uses retained samples for Real Time testing. Every month she will monitor and record data from some basic lab tests plus organoleptic tests. We now have data from 10+ years of testing.

    In all cases, the Rapid Stability testing has been 100% accurate.  And for some of the brands we manufacture for, we have been able to extend the use-by-dates where necessary,
    Dr. Mike Thair
    Cofounder & Chief Formulator
    Indochine Natural
  • PhilGeisPhilGeis Member, Professional formulator
    As Mike observed, rapid aging data are almost always confirmed with products in real time BUT decide now (not when the data has you in a panic) what you'll do if NOT confirmed.
  • PhilGeis said:
    Consider 1 and 3 months at 45C as relevant to 1 and 2 year exp. dates.  Wouldn't presume anything in rapid aging predicts 3 years.
    Get 1,2 and 3 year real time data.  1 and 2 confirm rapid aging and 3 is instructive to preservative systems even if product no longer on market.

    Also see how US FDA sees stability testing of OTC drugs.

    https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/inspection-technical-guides/expiration-dating-and-stability-testing-human-drug-products
    Thank you @Ph@PhilGeis! :smile:
  • tecnico3viniatecnico3vinia Member
    edited January 24
    mikethair said:
    We do the standard Stability Test at 45ºC for three months (in an incubator). Then our QC Manager uses retained samples for Real Time testing. Every month she will monitor and record data from some basic lab tests plus organoleptic tests. We now have data from 10+ years of testing.

    In all cases, the Rapid Stability testing has been 100% accurate.  And for some of the brands we manufacture for, we have been able to extend the use-by-dates where necessary,
    Thanks @mikethair! :smiley:
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