Injection Pen storage question (glargine)

[Kathryn Elizabeth]

Instructions for the JuniorStar injection pen say that the pen itself should not be stored in the fridge because it can cause the mechanics of the pen to malfunction.

I understand that the glargine insulin cartridge only last 28 days outside of the fridge yet can last a lot longer for veterinary use if stored in the fridge, but if using with a pen, what is the optimum way to do this? I am not sure that inserting and then removing the 3ml cartridge of glargine into the pen every single time is a good thing to do either, but it seems like that would be the only way to store the insulin in the fridge whilst not storing the pen in the fridge.

Vet suggested storing whole unit in fridge with cartridge permanently inside and just removing whole unit one hour prior to use to allow it to come to room temperature, but i think that is unrealistic for the lifestyle of the people i am assisting with their cat. (Syringes and vials are not an option for them either at this stage, so need to get pen usage correct, and avoid wastage, as cat is only on 1 unit twice daily).

Thank you.

 

[Sienne and Gabby (GA)]

We advise against using the pen with pen needles. Instead, we use a syringe to draw the insulin out of the pen. The pens do not allow you to use a dose that is in increments of less than 1 unit (i.e., 0.5u, 1.25u). If you look at some of our members' spreadsheets, you'll see that doses are not only in whole unit increments. In addition, I don't think any of us have ever had an issue with the pen mechanism not working if the insulin is stored in the refrigerator. In fact, until you purchase a pen or box of pens, they are refrigerated.

In addition, if you are concerned about waste, you have to prime the pen with every use. You are waiting a unit of insulin twice a day if you use the pen to inject.

I'm very glad you switched from glipizide. It's not a great insulin for cats. With Lantus, please be sure to always get a pre-shot blood glucose test and to get at least one additional test during both the AM and PM cycles.

 

[Kathryn Elizabeth]

Thanks for your reply.
This pen (JuniorStar) does allow dosages of 0.5units, it is not a disposable one but a reusable one, and the refrigerated glargine cartridges are inserted into it. It may be stored in fridge at time of purchase but idea being that it is removed from fridge and then kept at room temperature and that the mechanism of the pen works best this way (at least that is my understanding after reading manufacturer's information).

We are using 8mm needles so should be enough to penetrate to the subcutaneous layer.
The owners feel too afraid/lacking in confidence/competence to use regular needles at this point, and myself and their vet are doing our best to guide them to cope with what feels manageable for them.

It's good to know that you don't recall hearing of anyone having issues with pen mechanisms stored in the refrigerator, although i imagine the issue wouldn't be overtly obvious at time of administering and may just affect the dosage without one being able to tell specifically that that is occurring (instead for example might one see greater fluctuations in blood glucose that may otherwise have not been there if the dosage had worked better, but i am just hypothesising here).

I have been reading a vet research paper which says that wastage with reusable pens has been measured to be less overall than with a syringe - granted, maybe not for all the pro users on this board, but probably for the majority of less detail oriented people out there. Mind you, this quote they provide is I think from a human study and obviously human doses are bigger in general hence more likelihood for wastage in human usages, but anyway, the point is that we are trying to keep wastage minimal within the reality of using a pen and in awareness of the fact that the pen will indeed waste some of the insulin during priming).

"The perceived wastage of insulin with the air shot
is a misconception. A human study comparing wastage of
insulin in people using vials and syringes versus pens and
cartridges showed an overall wastage of almost 30% less
in those using pens.33 The decreased insulin wastage with
pens was thought to be due to improved accuracy when dos-
ing." (source:
Krahulec B, Strbová L, Seböková E, Cárský J, Klimes I. [Comparison
of insulin loss in treatment of diabetics using the classical syringe or the
insulin pen (Novopen II)]. Vnitr Lek. 1996;42(9):640–645. Slovak)


We will keep feeling our way forward with the info and experience we can find and create

 

[Sienne and Gabby (GA)]

It sounds like the pens you're using are not what we typically encounter. The Lantus cartridges are not available in the US thus we would not be using a reusable pen housing. Whether this particular variety of insulin pen is more temperamental than a Solostar or other pen that is disposable is not something I can reliably comment on. It sounds like you are helping Gandi's caregivers get comfortable with the entire process of feline diabetes management so thank you for doing that!

Not to be a research snob, I have no clue how good the journal is where the paper is published. It's also a 1996 article which in my world is old. I have access to a veterinary library and can't find the article.

 

[Larry and Kitties]

The problem with refrigeration in-use pens is that the temperaturing cycling can result in air getting into the actual insulin vial/cartridge in the pen. Air is compressible unlike the actual insulin and that can result in real dose of insulin be different than the dialed dose of insulin. This is a concern especially with cats because the dose is typically very low.