Why do drugs have expiration dates?
 

I keep a bottle of A.S.A (aspirin) in my desk drawer at work for those rare days when I need to quell a headache. I've long since passed the expiration date on the bottle yet they seem to still take care of that headache. So what is it that "goes bad" in an aspiring after a long period of time? I would think that the ASA in the tablet is still there and will still be there forever. Does the chemical act with the air and deteriorate?

slow degradation of the active compounds. Usually hydrolysis products.

Yes.
As ASA ages, it get a very vinegary smell.
A lot of drugs lose potency due to exposure to heat and or oxygen.

For the non-chemists, that means that the drug reacts with water, which is absorbed from the air. That's why some drugs come with dessicant packets.

Sometimes they react with light, sometimes they just change crystal structure but not molecular structure.

The experition date is usually valid, and not just a moneymaking strategy.

It's all a conspiracy so you have to buy more drugs from the big, evil pharmaceutical companies...

After a while, they all turn into deadly poison!!! BWAHAHAHAHAHA!!!

Henri,

Missed you at yesterdays DE. Your 911 will expire if you don't drive it often enough...

Hope all is well with you.

If your thinking about aspirin (aka Acetylsalicylic Acid) than Nostatic is correct, they do undergo oxidation - like all things. You will know when your aspirin goes bad cuz it will smell like vinegar (aka Acetic acid). This is due to the aspirin oxidizing. Take a whiff of an old aspirin bottle. If it smells like vinegar then they have lost some potency.

Most all drugs have a few carbon rings and some carbon chains - few are complexes with metals but the majority are an arrangement of carbon and hydrogen atoms and maybe something else to a small degree. Carbon Hydrogen bonds are susceptible to oxidation and water vapor and heat and even light act as a very nice catalyst. That is why you are supposed to store then in a dry, cool place and why the bottles are normally dark. This is to protect them form oxidizing - when they oxidize they loose their reactivity or potency. The dosage is balanced out for peak efficiency but if it is a little less reactive (potent) than design it may be very ineffective.

BTW - 10 grains (2 tablets) of Aspirin is all you need for reducing inflammation, any more and the body just doesn’t process it

Plausibly. ;)

Depending on what substances and in what form and package - some will go a looong time past the exp. date with most of its effect intact.

I am a wicked doctor. I have given for example antihistamines (for allergy) and cortisone to my kids that expired up to five years ago. Intact response and no ill effects. From now on you may call me Dr. Mengele. and please don´t try this at home. ;)

I thought the expiration date was the date it's supposed to still have 100% effectiveness. So if you use it after the date, it's just not as effective.

Essentially yes. Many medications will form degradation by products after a certain amount of time. And FDA mandates that drugs undergo testing to determine how long they remain stable under certain storage conditions, hence the expiry date.

It is also, sometimes, the date beyond which the drug company cannot guarantee a certain level of clinical efficacy.

If you have no kids, put them in ziplocks with a bit of rice in the back of the top shelf fridge.

Heh, I use expired meds all the time. I just don't use meds enough to keep the fresh ones around. I also have not noted any differences in efficacy.

But please don't try this at home, we are professionals :p

Jorian, I took the car cover off and drove the Duffy Lake Road with my wife a few weeks ago. We left at 7:30AM and got back by 5:30PM. Beautiful and fun drive. Yep, all is well, thanks.