Why my potassium citrate gently weeps
December 13, 2014 11:20 PM   Subscribe

My pillbox is gross, and it seems to be coming from a pill. What the heck?

I got organized and stored the potassium citrate and propranalol that I take every morning in a pillbox that has 14 little closed plastic compartments. I did this during the summer with no problems that I recall, but as of a couple of weeks ago, the compartments were wet inside. Initially, I thought I'd had damp hands when I put the pills in, but a couple of days later, I opened a compartment to find beads of moisture on the potassium citrate pills. (In fact, it was dissolving the propranalol...)

Further data:

- 7 of the compartments have potassium citrate and propranolol. The other 7 do too, but they have other stuff in them as well (I'd prefer not to list all of them here, but memail me if you think it's relevant). The compartments with the other medications and supplements did NOT have the weeping effect.

- The rainy season started around the same time that the issues showed up, I guess.

- I did attempt to google it, but all I got was stuff about weeping sores and wet granulation methods. Not useful.

I have no idea what's going on, but I'd really like to be able to save time by using my pillbox, like the good old-lady-in-training that I am. I'm really curious as to what is happening (chemically/physically) and how I can prevent it. Any ideas?
posted by wintersweet to Science & Nature (6 answers total) 3 users marked this as a favorite
Best answer: Potassium citrate pulls moisture out of the air to such an extent that it can "sweat". It's possible that one or more of the pills in the other 7 compartments also acts as a desiccant, keeping the air dry enough to prevent the potassium citrate from sweating.

You can get small desiccant packets (the Do Not Eat packets in dry foods) and place one in the bottom of each compartment.
posted by WasabiFlux at 11:43 PM on December 13, 2014 [3 favorites]

Best answer: I'm really curious as to what is happening (chemically/physically)

To throw some vocabulary around: your potassium citrate is exhibiting deliquescence. More generally, the property of being attractive to water is called hygroscopy (adjective: hygroscopic); I think deliquescence is specific to salts.

So yeah, you need to find something that likes water more than the potassium citrate does and throw that in there as a dessicant.
posted by fermion at 12:02 AM on December 14, 2014 [3 favorites]

Favorited for the title.
posted by Bruce H. at 8:19 AM on December 14, 2014 [9 favorites]

Response by poster: It occurs to me that the potassium citrate doesn't exhibit this behavior in the bottles that it comes in, which are big, fat amber plastic prescription bottles. Any idea why? There is no desiccant in the bottle. (My guess is that those close more tightly than the pill box does, and less air gets in, but I'm totally speculating.)
posted by wintersweet at 9:16 AM on December 14, 2014

Best answer: Most multi-compartment pillboxes are not airtight. If you look carefully, there are a few with gaskets to keep humidity from reaching the contents, such as this vitacarry pillbox. I've had good results with one similar to this airtight Vita-fresh pillbox, after having trouble with pills (not potassium citrate) getting moist in a non-airtight container.
posted by artistic verisimilitude at 9:49 AM on December 14, 2014

Response by poster: Thanks for all the useful answers. I've ordered an airtight and watertight pill case (that would have been SO useful in Korea last fall, when my backpack and other pill box got soaked in the rain!).
posted by wintersweet at 10:52 AM on December 14, 2014

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