I have a question – we all know that if you freeze insulin you’ll destroy it. So as you cool down insulin from room temperature there will come a point where it’s no longer any use. Is this a gradual thing – i.e. insulin becomes less effective the more “damaged” it becomes; or is it a binary thing – i.e. it’s fine until suddenly its ineffective?
Given insulin is a protein (I think!) I guess it would be more a binary thing – like frying an egg, it’s either runny or cooked.
In case anyone’s interested, I was wondering about this after leaving my spare insulin in the mini-bar of the hotel room I was staying in Oxford last week. It was a much colder mini-bar than I thought it would be.
Insulin is indeed a protein, suspended in an aqueous solution. Once it freezes, it is rendered ineffective – because once it thaws, the insulin molecules clump in a different way, and dont work properly. But it does actually have to freeze and thaw before that happens. (And I believe the freezing point to be just below that of water.)
@tim when I was on pen cartridges & renting a place with an really, really over enthusiastic fridge I quite often froze novorapid to the back of the fridge through the cardboard & plastic packaging.
Only the end vial closest to the element would freeze & even then not fully because of the mass of insulin & the heat transfer propertys. That cartridge would seem less effective & I’d need a few extra units, played havoc with the lantus though.
Kept our insulin in many a minibar over the years w/o any problems & if you think about it miniatures aren’t that different in volume to insulin… The bigger problem is getting back to find your insulins been replaced by a bottle of bells ‘scotch’