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## Freezing Point of a medication solution

Hi there, I'm hoping to finally get a definite answer in this forum for a question I've been trying to help my uncle with for quite some time now.  I've posted on other boards across the web and can't find an answer or I get chastised for not doing all the math myself but I've done the best I can. I'm just trying to help my uncle find an answer to a simple question he has.  My uncle was prescribed a glucagon rescue medication in case he has a severe low blood sugar. It is a pre-mixed solution in a pen device. According to the package insert this particular medicine uses Dimethyl Sulfoxide as a diluent. My uncle works outside quite a bit in a part of the country that gets pretty cold in the fall and winter and he needs to keep this with him at all times. He wants to make sure it won't freeze up in case he needs to use it.  When we looked up the freezing point of Dimethyl Sulfoxide, we found out it was 66° F. Does that mean this medicine could possibly freeze at a point slightly below 66°? The package insert says the storage temperature should be between 68 and 77 but it does say temperature excursions are allowed down to 59°. We just need to know the temperature that the solution will freeze at to see if he needs to try to switch to a different medication.  We have asked his pharmacist, physician, and called the company and no one can tell us what the freezing point is of this medication.

According to the package insert, the solution is as follows:

A 0.2 mL solution that consists of 1 mg of glucagon, 11.1 mg of trehalose dihydrate USP and 1.2 mg of 1N sulfuric acid, NF in dimethyl sulfoxide diluent.

I tried my best to figure this out on my own but I'm certain I'm doing something wrong.  I came up with an approximate freezing point of 65° F but that just doesn't seem right to me.

Contributor III

## Re: Freezing Point of a medication solution

Yes, DMSO has a melting/freezing point of only 66'F, and the small amounts of solutes in the mixture would depress that very much.  Of course, it will take some time to lower the temperature of a pre-loaded syringe from maybe 75'F to 66'F.  With a normal body temperature of around 96'F, simply keeping it in an interior pocket of any garment should prevent it from reaching a temperature low enough to freeze it.