Wednesday, February 23, 2011

Q & A: How Long Can Glargine and Detemir Insulins Really be Used Once Vial is Started?

Our pharmacist is telling me that determir insulin (Levemir) expires after 30 days. He claims that this is because of the risk of contamination.

At $112 a bottle, this short expiration date would make detemir cost prohibitive for my clients. Is detemir insulin actually stable for longer periods if kept refrigerated, as has been found with glargine insulin (Lantus)?

My Response:

Glargine is marketed for human use with a 28-day shelf-life at room temperature after opening. Similarly, detemir is marketed with a 6-week shelf-life at room temperature after opening of the vial.

The recommended shelf-lives for both detemir and glargine are relatively short, not because of lack of efficacy, but because of the increased risk of bacterial contamination with these multiple-use, injectable medication vials. The FDA believes that the insulin vials may have a high probability of becoming contaminated with microbes by the daily multiple punctures needed to withdraw medication when used past the insulin's expiration date.

For veterinary use, we generally recommend that both insulins be kept refrigerated, although the antimicrobial preservative in these insulins may actually be more effective at room temperature. Owners of diabetic cat or dogs use refrigerated glargine or detemir routinely for up to 3 months without evidence of problems occurring. The insulin should be discarded immediately, however, if any cloudiness or discoloration is noted.

This issue with bacterial contamination seems to be extremely rare. Pet owners are much more likely to accidentally drop and break the vial, than to have to throw it away because it develops discoloration.

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