Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Lmnre on 10/07/2012 23:27:01
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We all know the warnings about medications and temperature extremes (see quotes below). And key chain pill containers are convenient, especially for truly emergency pills like nitroglycerin for heart attacks.
Women tend to keep their keys in their purses, which are mostly safe by these standards unless left in the sun or a hot car. HOWEVER, men usually keep their keys in their pants pockets — and tightly against their bodies — for most of the day, and I'm thinking doing so would incubate their meds at 98.6F/37C for 16 hours every day, which is even beyond the more relaxed 86F/30C limit.
So, are "pills kept in pockets" really effective and safe? Are the nitro pills on grandpa's key chain merely duds?
Besides, when we take pills, they obviously reach 98.6F/37C inside our bodies and are bathed in moisture. Why all this concern about heat (and moisture)? Why is 24 hours at 98.6F/37C in our bodies okay, but the month of July at 98.6F/37C in a kitchen cabinet is not okay? What chemical reaction occurs after a week or a month, that doesn't occur within 24 hours?
Aspirin should be stored at room temperature, 20-25 C (68-77 F)
source (http://www.medicinenet.com/acetylsalicylic_acid/article.htm)
Pharmaceutical manufacturers recommend most of their products be stored at a controlled room temperature of 68 to 77 degrees, said Skye McKennon, clinical assistant professor at the University of Washington School of Pharmacy. In truth, that is the range in which manufacturers guarantee product integrity. Anywhere from 58 to 86 degrees is still fine, she said.
“During heat waves and cold spells, storage locations can go above or below those ranges, causing medicines to physically change, lose potency or even threaten your health,” Dr. McKennon said.
For patients with such chronic illnesses as diabetes or heart disease, a damaged dose of a crucial medicine, like insulin or nitroglycerin, can be life-threatening. But even common medicines can break down with potentially harmful effects, and you can’t always tell by looking at the pill or liquid that a problem has occurred, said Janet Engle, a pharmacist and past president of the American Pharmacists Association.
source (http://www.nytimes.com/2011/08/16/health/16consumer.html)
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Unless you live in a particularly hot climate, a pill in your pocket will be cooler than a pill in your mouth.
...And if you do live in a hot climate, sweat will keep a pill in your pocket cooler than one in a handbag - but the moisture may not be good for the medication either!
Similar reactions will happen at 37C as happen at 20C - only a lot faster.
The rates depend on the precise chemical reaction, but a rough "rule of thumb" is that chemical reactions double in speed for every 6C rise in temperature.
So a chemical kept at 30C will degrade as much in 1 day as it would in a week if kept at 20C.
If you are interested in the mathematics: http://en.wikipedia.org/wiki/Arrhenius_equation
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Do you realise that, once in the body, nitroglycerine has a half life of about 5 minutes?
It's the water and the enzymes in the liver that wreck it.
Obviously it's not the most stable of materials and the rate of decomposition increases with temperature.
Keeping drugs too cold is not usually so much of a problem unless they are solutions in water and you freeze them (just thawing them won't bring them back).
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Most pills are water-soluble, and are designed to dissolve and release their contents in a particular part of the gut where they will be best absorbed, and where the active ingredients won't be broken down by the wrong pH, or digestive enzymes.
Most pill packaging is not totally hermetic, and so if you keep them in a too-moist environment, some moisture will enter the packaging, and will start to be absorbed by the pills. This means that a pill designed to dissolve in the intestine may actually dissolve in the stomach, and be inactivated by stomach acids.
So its a good idea to store pills in a cool, dry environment.
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Thanks for your very good explanations.
PS — I noticed that my thread's title was changed, I'm sure, to make it more British-friendly, which is perfectly reasonable. The funny thing is that "to go off" means "to decompose" in British English, but means "to explode" in American English, which has a double meaning here if my heart pills are nitroglycerin!
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Talking to a guy who does Quality certification for a pharmaceutical company, one of the worst things you can do is leave your pills in a locked car, in the sun. This can break down the active ingredients very quickly.
Also, see the recent story about using silk to preserve vaccines at higher than normal temperatures - http://www.thenakedscientists.com/forum/index.php?topic=44806.0