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How does one use the results of Accelerated stability testing for chemicals to determine the typical Shelf life and Expiry Date?

e.g. Suppose the typical storage is going to be at 25 C and the expected shelf life is 2 years (as printed on the labels or the best-before date).

Now in the interest of time suppose we test at a higher temperature how do we extrapolate those numbers to the typical shelf life at room temperature.

Any standard protocols for this? Also what's a reasonable high temperature to use for the accelerated tests. I am dealing with a fairly temperature stable & nonreactive material here. 60 C?

Stability testing seems quite common in the Pharma industry etc. so I'm sure there's norms out there.

Note that I'm not dealing with a drug / medicine / food etc. This is strictly for an intermediate which will not be consumed directly by the end user.

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    $\begingroup$ What kind of intermediate is it? Packaging, excipient, processing additive (removed later)? Have you checked for FDA and USP guidance docs (or whatever applicable govt. body or pharmacopoeia is applicable where you live)? ASTM has documentation of accelerated aging, but I think it is mainly for materials. $\endgroup$ – J. Ari Mar 24 '17 at 13:08
  • $\begingroup$ @J.Ari Thanks. It's a molecule that goes through 3-4 more processing steps to lead to the API. $\endgroup$ – curious_cat Mar 24 '17 at 13:09
  • $\begingroup$ The molecule itself does not have a USP / FDA standard monograph. My two big questions are what temperature to test it at and how to extrapolate the accelerated testing results to typical temperatures. $\endgroup$ – curious_cat Mar 24 '17 at 13:11
  • $\begingroup$ Your accelerated test temperature will likely be a function of what the final product (or some representative intermediate hold state) must be kept at. If everything has to be kept cold (for ease we will say cold = not room temp), then studying at room temperature could be sufficient. I'm less sure about room temperature stable products. I would propose going to worst case storage temp of the product. This article below may help you figure out the extrapolation. biopharminternational.com/… $\endgroup$ – J. Ari Mar 24 '17 at 14:06
  • $\begingroup$ @J.Ari Sorry, I should have been clearer: Sure studying at Room Temp. would be sufficient. The accelerated testing is only to save time. e.g. We believe 2 years is a reasonable shelf life based on what we know. But we don't want to wait for two years for test results. So we raise T and extrapolate results to room temperature. That, I believe, is the motivation behind accelerated testing. $\endgroup$ – curious_cat Mar 24 '17 at 14:08
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Yes, there are guidelines. For example from ICH and WHO for pharma, and from CIPAC for pesticides. Some can be downloaded freely.

Yes, there are guidelines. For example, from ICH and WHO for Pharma, and from CIPAC for pesticides. Some can be downloaded freely. Accelerated stability tests are generally not accepted as replacements for full-scale stability tests, but can provide an indication of the formation of undesirable by-products etc.

As a rule of thumb, a very general rule, chemical reaction rates in-/decrease by a factor of 2 for every 10C the temperature changes. According to this rule, if the test temperature is raised from 20C to 30C, the test period could theoretically be halved. However, if you look through the temperature/time combinations in the guidelines, you will find this relationship hard to find :-).

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