Will Differin (adapalene ) still work after freezing?
January 11, 2020 10:17 AM   Subscribe

Canada Post dropped off a package at my side door without a notification and I didn't see it for what was probably a couple of days. It's been very cold (-15C / 5F). Online instructions say to protect from freezing. How much would it actually impact the efficacy?

Differin isn't available in Canada (I purchased it online and a friend sent it to me). While it wasn't overly expensive I'd like to know if it's still worth using. Thanks in advance!
posted by mireille to Clothing, Beauty, & Fashion (5 answers total)
Hmm, IME, the instructions for most topical medications do say to keep them from freezing. Your Differin will still be safe to use, and likely will still be just as effective, but if it has an unusual (gritty, flaky, or runny) consistency after being thawed, I would probably get another tube if I were you.
posted by un petit cadeau at 12:17 PM on January 11, 2020

An FDA document says freeze-thaw cycle stability for adapalene was found to be 3 cycles at -20C, and long term stability was at least 2 years at -20C. This is testing done to ensure activity/efficacy after extreme temperature changes that can a normal part of transport. See page 22 of this large pdf.

If it stayed cold the whole time it was outside, it's likely fine. Storing something in a kitchen freezer for a while (the frost free type, versus the old school or deep freeze ones that hold a temp and build up frost layers) can subject it to multiple freeze/thaw cycles, depending on the freezing temperatures of the substance. Home kitchen freezers keep frost from building up by cycling the temperature.
posted by neda at 1:50 PM on January 11, 2020

Response by poster: Thank you neda, I was wondering about transport temperatures too so the science backup is really helpful. It hasn't been above freezing here in recent days so I'll use it. Much appreciated!
posted by mireille at 4:31 PM on January 11, 2020

Best answer: Hi, I disagree.

The freeze thaw stability you're looking at in the FDA doc is stability of a sample in blood plasma, *not* a sample of the drug product that you want to put on your skin. These are totally different things and do not necessarily map onto each other. I think this is a pharmacist question and not an ask-the-internet question.

Companies don't want to put warnings on their products unless they have to, which meant when they did the freeze-thaw testing on their drug product, something went out of range, and they were forced to put the "Do Not Freeze" warning on. I just came across a product that required a "Avoid Prolonged Exposure to Light" warning because when they did a photosensitivity test, it lost 50% of its potency.

I work in this field, I used to do a lot of these tests, I wrote the labeling, I now check that other people do the tests correctly. I'd call a pharmacist.
posted by Vatnesine at 8:07 PM on January 11, 2020 [4 favorites]

Response by poster: Decided not to use it after all given your answer, Vatnesine. Appreciate the reply!
posted by mireille at 1:37 PM on February 10, 2020

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