So our my niece was visiting for the weekend. She got in late on Friday and a bag of her stuff got left outside in the car for the night. It got below zero here and in the morning of course everything was frozen solid- her insulin, pierced ear care solution, contact lens solution, etc.
How do you tell if it’s OK to let something freeze. Her insulin clearly said not to, but the ear care solution (benzalkonium chloride I assume) and contract lens solution just said "store at room temperature). She had enough insulin in her pump to last the rest of her visit and she opted to replace the other liquid stuff and assumed her solid medication (prozac and seroquel) was OK. so it’s just a question of curiosity at this point.
If something isn’t supposed to be frozen, or alternatively can’t get too hot, how to they ship it? Do they ship it in heated and air conditioned trucks, or just not ship it if the weather isn’t mild, or just ship it anyway and despite the warnings it usually doesn’t get wrecked?
Wouldn’t be easier if everything was labeled with a temperature range it was allowed to be at for either long term storage or temporary shipping or forgetting in the car?
There are many answers to your question. However …
Its bad to freeze protein solutions. They are large biological molecules, and they can be sheared – cut – by growing ice crystals. Also, as the water freezes, the proteins find themselves gradually without water, and may find each other, and clump together. And never dissolve again when thawed. And that might be visible, or not.
Maybe you’ve seen freezer burned meat. Maybe you haven’t. Maybe you ate it anyway. But I think we can all agree – insulin is different.
Sodium chloride in water, when frozen and thawed, should behave the same as if it were never frozen. Its small. Its made of two elements. What would our world be like, if frozen ocean water became toxic? Always be ready to ask yourself this question – even if you’re not a scientist: What would the world be like if {magic happened}… Would we survive these things when they were beyond our control? Pre-industrial societies? Animals? Sub-sapient hominids?
BZK is a problem. Its mid sized. Technically, its hard to generalize. One extreme or the other is the case, and once we know it, “Oh, how obvious.” But not until we check.
Pharmaceuticals are definitely tested to see if they can survive exposure to temperature extremes. If they can’t, they are definitely labeled with restricted ranges. And yes, pharmaceutical manufactures definitely produce, store, warehouse and ship within the temperature ranges required. And document the temperatures the pharmaceuticals have experienced, and store those records in perpetuity.
I’ve received shipments of medicine that needed to be kept cold but not frozen. They come in Styrofoam boxes; there’s some kind of ice pack inside, but the medicine was buffered by padding so it didn’t contact the icepack directly. Shipping was overnight and the ice pack was still solid. I don’t remember what the medicine was, something for my dog, but I assume they do the same for human medicines.
Food delivery services like Blue Apron etc. work the same way, except in cardboard boxes rather than styrofoam. Proteins like chicken breasts usually DO go next to the icepack and in some cases they are partially frozen; I know I had shrimp in a couple of deliveries and it was frozen (on purpose) and remained so until I got it into my freezer.
p.s. Refrigerated pharmacy shipments usually come with an indicator that changes color if the temperature dips below freezing. I never personally saw one that did.
Depending on what brand and model of insulin pump she uses, it would be fairly easy (especially if she’s been on that brand pump as long as she’s been diabetic) to assume there’s enough capacity to last her long enough that she wouldn’t have to refill overnight. The largest consumer-available pumps can hold up to 480 units.
By the time it’s dissolved, it’s not even that: the ions have separated and each of them is surrounded by its own personal ball of water.
Arkcon didn’t mention it directly, but insulin is a protein. The explanation he gave about shearing is one big part of why its solutions should never be frozen. Another part is that proteins are long ribbons, think of a skein of yarn, where every part has to be in a very specific position in order for the protein to be able to work properly: if freezing changes that configuration irretrievably (even without getting to the point of chopping up the molecule), the protein becomes useless. It is not uncommon for the working configuration of a protein to be different from its most-stable one; freezing can shuffle the protein to the more-stable configuration and then, because that one is more stable, it just won’t go back to the other position.
The contact lens solution wasn’t sodium chloride. I don’t want to go outside and dig the bottle out of the trash but it had a bunch of complicated ingredients in it. I guess it’s for sterilization as well as cleaning gunk off. I’m not sure of the model number of her insulin pump but it was pink and by Medtronic and she had just filled it before leaving on the trip so there was enough to last until she got home again last night so she didn’t have to deal with trying to get a replacement prescription filled here.
Is kind of the idea the more complicated the ingredients are (proteins as opposed to sodium chloride) the more likely freezing is going to mess it up?
In short, there was not a difference in effectiveness, but there was an increase in clumping of the protein. Rate of thawing made no difference. Still, I wouldn’t recommend using previously frozen insulin unless in dire circumstances with no other option.
As proteins go insulin is a tiny protein. Very small chain only 51 amino acids long. But that is positively mammoth compared to other chemicals like the benzalkonium chloride in the ear care solution mentioned in the OP.
That’s a factor; another is how soluble they really are. Something like eye drops is a solution: water with some active ingredients which actually are water-soluble. Milk or mayo aren’t solutions: they’re emulsions, where little “blobs” of water-insoluble material float in the water; cold temperatures is one of the situations which are likely to break the emulsion, separating them into two different parts that will not mix back together just by heating them back up.
(I say water-soluble and water-insoluble because any given substance will be soluble or not in different solvents: NaCl is supersoluble in water but very little in oil; fatty acids are highly soluble in oil, very little in water)