UKC

why do drugs like antibiotics etc go out of date - do the chemicals decay/change or is ot a marketing/health/safety thing ?

In reply to lithos:

First couple of links answer your question:

https://www.google.co.uk/search?q=why+do+drugs+like+antibiotics+etc+go+out+...

In reply to lithos:

Do you have spare antibiotics lying around? If so why?

In reply to mattrm:

thanks ive now read them, they dont tell me why but they tell me that (assuming its not niro, insulin and a few other things)...

* they are safe to take
* they may not be 100% potent
* there seems to be only 1 study !

In reply to MG:

yes cos i didnt take them cos i didnt need them as they were prescribed as an in case
it flares up which it didn't. It got me wondering thats all

In reply to lithos:
Various reasons for drug shelf life limits:

1) The active ingredient degrades over time to become less effective.
2) The active ingredient degrades over time into impurities which may not be safe.
3) The drug develops rather more biology than you'd like.
4) The carrier or mechanism for taking the drug becomes less effective over time.
5) Because the manufacturer didn't want to invest time in doing long shelf life studies because they are pricey and awkward. If you've got a short supply chain and fast turn over then why would you waste time registering a 3 year shelf life if people don't stockpile the drug?

Depending on the type of drug which of these issues is most important will vary. Generally I'd avoid taking out of date medications unless you know why the shelf life was set that way and I doubt that information is available unless your hands on the registration documents.

In reply to myself:

actually i've no idea as I havent checked the date i just assumed it

In reply to lithos: The point is that taking less than a full course of antibiotics is anti-social because if not all the bacteria are killed, it encourages resistant strains to develop. Throw them away.

http://blog.practicalethics.ox.ac.uk/2010/08/the-ethics-of-prescribing-anti...

In reply to lithos:
Much depends on the formulation and storage.

Couple of examples: most tablets aren't going to go off quickly if stored in the dry. But the same is not true of liquids.

In my lab days, I found that antibiotics such as penicillins in liquid solution will deteriorate very quickly (1 day or less) at room temp, losing all potency. Will last a couple of weeks in the fridge, and indefinitely if frozen. What this means for clinical use I can only guess: that they would be probably still safe to use, just totally ineffective.

In reply to bullybones:

interesting how fast they loose their potency - i presume (my chemistry is non existant
O level 35 yeas ago) they cant find a more stable solution ? I dont know how anti biotics work or what they are chemically so how they 'degrade' is open - ill have a poke about when i've done some work

In reply to lithos:


blimey this makes interesting reading - injecting their cows antibiotics !

http://www.backwoodshome.com/forum/vb/showthread.php?t=27058

In reply to lithos:

Maybe it's just me but I'm sure I heard banjo's playing when I opened that link ;O)

In reply to lithos:

Penicillins contain a beta-lactam ring which isn't the most stable of systems. Newer analogues of penicillin are more stable, but some effort had to be put in to increase their resistance to stomach acid.

In reply to MG:

Sometimes people are prescribed antibiotics 'in case' they need them, as in this case. I have a course of antibiotics at home for just that reason. Having 'just in case' drugs in the house doesn't automatically mean that a person will fail to take the full course.

In reply to Taurig:

thank you for that (and TC is far more polite than i was before deleting my response, and spot on)

In reply to MG:


There are plenty of legitimate reasons for having prescription antibiotics 'lying around'. Two obvious ones are:

i) your doctor issues you with such a prescription so that you have them and can self-administer when required to treat a recurring problem (my doctor has offered me such a service).

ii) for anyone travelling to remote locations where a medical kit might sensibly contain antibiotics.

I'm sure you can think of others.

In reply to bullybones:

I've got some drops for a recurring ear infection, that are now over three years past their use by date. I only need two goes with them and the problem is sorted for a while 6 months or so. I keep them in the fridge but when I go on holidays they've been in a hot tent all week too. The original package says once opened discared after 30 days!! never done me any harm - what??

In reply to lithos:

I work in drug stability testing and there is a very good reason for an expiry.
Essentially the drugs will degrade over time (different rates of degradation happen based on the local conditions, temp, humidity etc). As a result they lose their potency and can frequently break down into unsafe byproducts. Mainly it is that the drug will break down to a level below that specified in their drug stability profile that is submitted when the drug is sent for regulatory approval.
Basically best case is that the drug won't work, worst case is that they can cause you harm.
From someone who tests the things do yourself a favour and bin expired drugs please.

In reply to Graham T:

thanks for the info - they aint by their expiry date

In reply to lithos:

What about compounds like mdma? I heard that compounds don't break down unless you do something to them and therefore last indefinitely. But I've always wondered how true that was.

In reply to stp:

Depends entirely on the compound, hard to make any generalised statements about it. Some, generally more simple than you would find as a drug, could potentially last for decades with little degradation, if stored well. However, unfortunately for chemists, most will react and break down over time in the presence of light, oxygen, moisture etc. without anything being 'done' to them. Like I say though, hard to generalise.

In reply to lithos:

I store a range of meds in the freezer, I think it keeps them for many years past the use by date. I only do it with diamox and antibiotics though, not nifedipine or anything else I might have to actually rely on to save my life, better off sticking to the rules on those I think.