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

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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