Expired insulin: 9-month-old open Novolog pen experiment

Medicines Insulin
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It is our turn to report on our expired insulin experiment. We focused on evaluating what happens to insulin that has been opened, then left in the fridge.

We opened a Novolog insulin pen in August 2016, used it once, and left it ouf of the fridge for a week. We have left it in the fridge ever since. About once a month (very approximately), we have taken it out of the fridge, brought it to room temperature for a few minutes, then put it back in the fridge.

Yesterday we experimented with it. What we found:

  • The plunger had a little bit of initial friction. We had a hard time getting it going. For a few seconds, we even thought it was actually frozen.

  • We were able to inject after about one minute of experimentation. The insulin (a 6-unit dose) was effective, although my son went a touch high. it could well be due to his being a bit sick right now – or it could be that the insulin has lost a bit of efficiency. But – what is clear is that it still works.

We will continue experimenting with it over the next few weeks/months, and report.

[EDIT] added the first week out of the fridge which I had forgotten to mention.

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I inadvertently did a similar “experiment” about eight months ago.

I had accidently left my bag in the shopping cart at the grocery store. I didn’t realize it until late that night, so I started a new penfill carpule in a spare pen.

I picked up my bag two days later and just put the pen back in the refrigerator. I was hesitant to use it because of the loss of chain of custody. (Ok, so I’m a bit paranoid).

Long story less long, I finally relented and put the pen back in use about two weeks ago (it was about half full). Noticed no difference in efficacy.

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I can understand that. I don’t think paranoid :slight_smile: – or maybe I am too?

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