[manOman]

I have no academic background whatsoever and just recently have an interest in this sort of thing.
just wondering, what is the shelf life for drugs after they've passed their expiry date? and elicit drugs? supposing i had syringe of heroine or fentanyl or something like that, (i dont have) how long would it stay effective for as a sedative and painkiller? and could it stay effective for longer if kept in the fridge for example? or are there any other ways to lengthen the life of them? i know this question seems suspicious but rest assured i am not mixed up in drugs, im just a curious member of the public. pm me some answers if you want or answer here i dont mind. If this is the wrong part of the forum for this then i apologize.

cheers
Dean

[Borek]

Asking about drugs is a sure way of raising suspicions, so I am going to watch the thread closely, but the question is perfectly valid.

There is no single, simple answer.

In general every drug is just a chemical compound, in most cases an organic one. Most organic compounds will slowly decompose/oxidize in the presence of air, especially at elevated temperatures and in the presence of light. The larger and more complicated the molecule (and most drugs are far from being simple) the easier it decomposes (not a hard rule, but good enough for practical purposes).

Problem is: there are no more rules. Some compounds are quite stable and if properly stored (tightly closed dark bottle far from heat sources) have shelf life of many years. Some are quite fragile and even in low temperatures will decompose in weeks or even days (or even minutes, but these are rather unlikely to have any therapeutical value).

So the best answer that can be given is: question is valid, but it all depends on the exact compound/drug.

[jeffmoonchop]

The expiry date is the shelf life. It will have been experimentally determined by the developers. It depends on their specification as to when they think the drug is no longer usable or within the potency specification. For some drugs, potency may decrease linearly as the active ingredient degrades. But for others, a small degree of degradation may cause a large decrease in potency. All of these things would have been determined by the developer and submitted to the regulatory authorities for acceptance. Normally these regulations are very strict.