Despite what the documentation says, if you store an opened vial in a refrigerator, you can continue using it for at least a year. At least that’s been my experience over many, many years. I would run it dry.
Not only that, I’ve used vials that have been at room temperature for months without issue.
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A year? Seriously?
I figured the documentation was overly conservative but… wow.
You don’t believe that insulin will last a year, opened, in the fridge?? Trust paytone.
I find it somewhat surprising that it would last that long, yes. Why? Because I actually have read a lot about the nature of insulin chemistry and because my wife’s a microbiologist who deals with proteins like this quite a bit.
Many of them are very, very sensitive to minor changes in temperature over pretty short periods of time. That’s why you get a fever when you get sick because your body “knows” that certain parts of bacteria and virus lifecycles require proteins that have a very narrow band of temperature within which they can function for long. If your body raises it’s temperature long enough all the bacteria/viruses will die because of a few degrees (F) temperature elevation. At that point it’s a question of which creature survives that temperature longer: you or the disease. Usually you win that one.
Insulin is known to be somewhat temperature sensitive ( “somewhat” compared to some other known life proteins some of which are many times more sensitive). Where exactly the demarcations are for insulin no one actually seems to know, at least not that I’ve found. There’s data that’s kind of all over the place on this in the lab literature.
From what I have found and read in serious research literature on it, it seems that what is known however is that insulin does have some serious susceptibility to heat with some studies showing a massive decrease in bioavailability as temperature rises, with decreases in effective concentration accelerated by from 4x to 14x as temperature increases by increments of 10C. The reasons for this variation seem to be unknown.
This however has created an overall model of insulin’s life at various temperatures. The theoretical models produced indicate that exposure from fridge temp of ~5C changed to room temperature, say 25C, should cause an acceleration in the breakdown of the insulin of between 4 and 28 times the speed it would breakdown if it were stored constantly at 5C and never exposed to light. Those same theoretical models suggest that if never exposed to light and kept at 5C the entire time insulin should lose no more than 10% of what we see as its “effectiveness” in 69 years… but practical laboratory experience highly suggets that such a thing isn’t actually true and that insulin, in practice, breaks down much faster than predicted by the model when the actual insulin is under the conditions the model provides.
Considering that to actually use the stuff you have to remove it from the fridge and it warms over time (though in short bursts), and the way this is suspected (suspected, not known) to affect the insulin it seems it should have an additive effect each time you do it. Plus the clear nature of the vial/pen ampule means it gets hit by light which is also known to break down insulin at what are, effectively, unknown rates because of the variation in the wavelengths of light that might hit the insulin, through what medium and for how long and at what temperature. So while the model suggests that the fridge should keep this stuff good practically forever, we know it doesn’t. We can also see that the predicted effects of temperature rarely work out as the models suggest, with insulin, in practice, surviving less time at each indicated temperature than the model suggests it should.
So without getting way, way further into the weeds here, from what I’ve seen it would seem that the model is a bit generous on survival times for temperature but there’s not a lot of data on what light does. That would seem, at least from my initial pass at this stuff, to be a much bigger player since you don’t generally jump into the fridge to do your injection nor do you do it in a darkroom.
So, yeah, in short it’s a pretty difficult kinetics problem that, from what I’ve seen of the actual lab research on it, I’d expect the manufacturers data to be quite conservative (for obvious reasons) but not conservative to the tune of 1/12th of reality and we know darn right well that it’s not 1/828th of reality or insulin would effectively last a lifetime and fairly extensive lab work indicates that it doesn’t actually do that.
When it comes to how the manufacturers recommend to treat the stuff… the manufactures would be wise to assume that everything is “worst case” for their breakdown scenarios and I have seen nothing that quantifies what those assumptions would be so I have no clue how realistic their “worst case” is. One kind of suspects that it would be based on higher temperatures for longer periods than would be reasonable and also include more light exposure than would be expected… but as I said, there’s no real papers on what assumptions go into those recommendations so I have no idea.
As such, I figure they’re overly cautious but I have no idea how much and I wouldn’t have expected it to be 12x reality.
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Can’t counter any of that other than share the experience in my personal “laboratory” aka myself, over 46 years. No issues. Of course that doesn’t mean it won’t happen someplace, sometime in the future. For my personal situation, I just consider the likelihood remote.
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I didn’t even read all of your post. Suffice it to say, that EXPERIENCE ALWAYS TRUMPS TECHNO JARGON. EVERY TIME.
I’ve had diabetes for 27 years and I haven’t ever thrown a bottle away before it was empty. I currently have in my purse a bottle of R and it’s been there since February. I only use a few units of it a day (as an adjunct to my Afrezza) which is why it’s been in there so long but I can’t tell any difference from the first day I used it. Even if it goes bad the decline from being out of the fridge with simple precautions will be gradual. Unless it got left in a burning hot car all day or frozen then you will not be likely to ever see a lessened effect.
I can’t say that I blame you for any of that. When experience shows that what you’re being told is overly conservative you go with experience.
Hence why I came here to ask people with more experience since I don’t have much.
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Yet you bothered to reply. The real question here is, as opposed to someone like paytone who answered honestly instead of flippantly, why would I care what you have to say?
I wouldn’t because you have nothing of value to contribute to this, or probably any other, conversation with your gross generalizations.
I actually know that because I bothered to read what you had to say before replying.
Fair enough. I don’t have the experience which is why I ask the questions of those who do since the information generally available is contradictory in many cases and doesn’t really answer questions.
“When in doubt throw it out” really isn’t much of an answer. Folks like yourself, Paytone, CJ114 and others have actually provided answers that I can’t really get anywhere else.
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This is what I had been thinking because I only have that problem with one batch of pens all from the same lot number. So I was wondering if that was something lots of people experienced. However, Paytone has pointed out a variable I hadn’t considered which is that it’s possible that the pen’s measurement system (internal screw) wasn’t dosing correctly and that the problem with that lot was actually the pen rather than it’s contents.
That seems pretty reasonable since it fits all the facts, explains the issue and still fits with people saying that generally insulin is, in years and years of experience, far more resistant to temperature than advertised.
It also just makes sense that the weak link would be a plastic widget.
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That makes sense to me as well. I did very occasionally have this same odd issue when I had been on boxed pre-filled pens and had forgotten about it because for the last decade or so have used a digital pen that doses Humalog/Lantus cartridges in 0.1u increments.
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ah, another resident for my Ignore list.