Is it Safe to Store Insulin in the Butter Compartment?

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Where do you store medications that need to be refrigerated? (Insulin, EpiPens, hormones, biologics…) In most households, they have firmly taken over the butter compartment. The door storage room is super practical for smaller items that you might not use that often and need their own space away from food and out of reach for children.

However, the door compartment actually has been designed to be a good deal warmer than the rest of the fridge, so butter would always be easy to spread — is it really the best place to store medications?

Most newer fridges have designated areas for different kinds of food with different temperature requirements: fish & meat, fruit & vegetables,… When medicine manufacturers and regulatory organizations such as FDA, EMA and ICH, refer to “refrigerated products”, they mean specifically a temperature of 2–8°C/36–46°F. Since we often store medications in our homes for 3–4 months, this might be worth a closer look.

🏁 Let’s test!

We wanted to see what the temperature actually was in a modern household fridge and if it really makes a difference where items are stored.

I spent a weekend at my parents’ and took advantage of their big and well-stocked refrigerator to test. It is a fairly new fridge, so it should be quite reliable. I decided to put MedAngel temperature sensors in four different places:

One MedAngel sensor for each spot in the fridge! In the fridge, the optimal range is 2–8°C. On the left, the sensors are still at room temperature, hence the app shows “too hot”. Test spots are the vegetables drawer at the bottom, the fish & meat drawer (supposed to stay around freezing point), on the center shelf and of course the butter compartment. (note the Nutella jar and variety of sausages, can you guess this is a German household? 🙂

The fridge was set to 8°C, which is on the warmer end of the optimal 2–8°C. However, the drawers promise to stay much cooler, “+0°C”.

Test Results are in!

Here we have a time/temperature graph over two days in the four different spots. The fridge was set to 8°C and it was used like a normal kitchen fridge — opened for breakfast, lunch, dinner and late night snacks:

The door compartment was overall the warmest, a good 3-4°C warmer than the center of the fridge. Also, this area is more sensitive to an open fridge door, since it is directly exposed to the room. Every time the door was opened, we can see a rise in temperature in all areas, but there is an extreme fluctuation in the door compartments in comparison to the center or drawers.

The middle shelf did quite well in the test of keeping approximately the set 8°C, fluctuating only little. Nice!

With these settings, the cool drawers came closest to keeping in the 2–8°C range. However, the lower drawer dropped really close to freezing point one night, for no apparent reason — not good.


So? Does this really matter?

Just how sensitive are our medications? They have been tested by the manufacturer to be “good” at 2–8°C until expiration date. If medications go below 90% of effective compound (eg insulin), they aren’t considered of acceptable quality any more.

When storage temperatures differ from the optimal range, medication quality diminishes gradually. For most medications, that doesn’t mean they become harmful, they simply lose some of their effect. From which point exactly it becomes critical? Hard to say  —  stability data is product specific and owned by the manufacturer, so it is not publicly available.

The InDependent Diabetes Trust however, has compiled information on this for insulin in general. They published a statement and a temperature excursion table by Novo Nordisk, one of the biggest insulin manufacturers. Note that this table refers to long term storage of insulin, not the one in-use:

“This table with permitted temperature and exposure times applies to single exposures only and repeated exposures to higher temperatures will gradually reduce the efficacy of the insulin.

It shows permitted temperature and exposure times that will not reduce the efficacy of the insulin, PROVIDED it is then returned to the refrigerator.” (read the whole statement here)

Information provided by Novo Nordisk originally and taken from an article by InDependent Diabetes Trust.

According to this table, insulin in the butter compartment of my parents’ fridge is not considered “refrigerated” after 4 days  —  and should be treated like insulin in-use, so taken within 28 days, or the respective in-use shelf life. Ouch!

But is this really true, would you see a difference when you take perfectly stored insulin vs a pen or vial that has spent a few weeks at 12°C?

Variations in medication effectiveness are not necessarily dramatic, you might not even notice them. Sometimes though, they can be. Diabetes blogger Sophie documented her freezing cold fridge and her son’s fluctuating blood sugar values in this post also on our blog.

“Given that we often store medications in our fridge for a couple of months, and that many factors can influence our wellbeing, why not rule out the temperature factor?”

Want to keep your insulin safe, no matter which fridge it’s in? Learn how MedAngel’s smart sensors work by monitoring the temperature and sending alerts to your phone.

Nov 6, 2017
Pharmaceutical sciences, now solving problems around meds and temperature.