Expired anti-biotics

[mistermack]

Does anybody have any info on whether antibiotics are safe, long after the use-by date? I'm talking about tablets or capsules that are stored at room temperature in comfortable dry conditions. 

Last night I had a horrendous toothache, I was nearly hopping round the room, I was downing Ibuprofen but it hardly touched the pain. In desperation, I dug out some old drugs that never got used, and I found a bottle of antibiotics that looked brand new, and I had written " for toothache" on the label. I would have used them, I was that desperate, but I looked at the date, and it was 2002 !!    Even so, I was in so much pain, I was hovering on the verge of taking them, but I resisted in the end.

Amazingly, I eventually passed out and got some sleep at about five O'Clock, and when the alarm went off at 8:30, pain gone !! And it hasn't returned. So I've been counting my blessings all day. But if I had taken the expired antibiotic, and woke up with no pain, I would of course have put it down to rapid action from the antibiotic. How could you not ??

So the moral of that story is that if you try a treatment, and get miraculously better, be very wary about concluding that the treatment worked.

But I'm left wondering about expired antibiotics. Does anyone have any info about whether it's safe? 

[CharonY]

The answer is for the most part, we do not know. Pharma companies have to provide expiration date based on specific testing regimen, that vary by region. But roughly, they are stored at specified conditions and then tested for quality and purity after time has expired. So if a company wants to claim e.g. a 3yr shelf life, they have to provide test data for samples that shows that the quality is maintained for at least 3 years.

There are also accelerated schemes (usually only allowed for claimed stability times of less than 3 years, I believe) where samples are stored at what is called accelerated temperature (to increase degradation rate).

Samples are analyzed at set intervals and based on that information manufacturer have to show what the maximum time is where they ensure no drop in quality. 

Unfortunately that data is generally not publicly available, AFAIK, so we cannot really project stability much. That being said, these estimates are conservative (as they have to show no difference between the beginning and whatever expiry date they want to submit). And degradation is rarely sudden. So even after expiry there is usually a fair amount of potency left, that drops over time. The one thing to look out for is if there are known degradation products that might be harmful, and there was some discussion about that surrounding tetracycline, for example (but as far as I recall it was no clearly linked to the drug).

[TheVat]

Another problem with decreased potency is that, if it's an antibiotic, say amoxicillin, you might actually help any offending bacteria develop an immunity to that compound by offering a weakened sample.  You really want the full potency.  For a toothache, you also want a dentist - the problem might not be bacterial at all.  

NSAIDs are probably okay for a few years after expiration, and I've used old acetaminophen (paracetamol to you Limeys) to good effect up to seven years iirc.  There are no hazardous decay products, they're just weaker.  

[geordief]

My partner got an attack of shingles ,naturally on a Sunday at the beginning of this year.  We were unable  to even see a doctor until the following day.

I knew how important it is to take the antiviral as soon as possible and I happened to have some left over medication from my own bout of shingles around 8 years previous to that.

 

I had kept them for such an eventuality(I have already had shingles twice)

I thought I should ring around the hospitals and the all night medical numbers for advice as to whether we should use these date expired medicines until such time as we could get  proper medicine from a doctor.

I was repeatedly  told not to do this (some circumlocutions) and as a result we started the treatment some 36 hours later than  we otherwise might have.

Should I have disregarded this advice and started the treatment anyway with the old medication? (acyclovir ,from memory).

As it turned out my partner has had to be prescribed the shingles antiviral 3 times since and ,some 10 months on from the initial infection  is just now ,hopefully putting it behind her.

I understand that the medication I had had doubtless lost efficacy but felt they might have been of some use in the circumstances .

But I didn't want  to go against the  medical advice I was given over the phone.

[StringJunky]

@geordief Are you aware there's a vaccine now for it and existing sufferers can take it to deal with future eruptions? Over 70 it's free in the UK.

[geordief]

6 hours ago, StringJunky said:

@geordief Are you aware there's a vaccine now for it and existing sufferers can take it to deal with future eruptions? Over 70 it's free in the UK.

Yes ,I know it is available

I have read that it is effective but less so than the Covid vaccine.

I have a penchant for putting things on the long finger  and especially so when it comes to visiting the doctor....

The reason ,incidentally that my second shingles infection also went untreated was that it also , naturally showed up on a Sunday -as well as my being convinced that you could not get shingles twice. (so that I ignored the signs until it was quite late and so had to go to hospital for a week)

[CharonY]

20 hours ago, TheVat said:

Another problem with decreased potency is that, if it's an antibiotic, say amoxicillin, you might actually help any offending bacteria develop an immunity to that compound by offering a weakened sample.

So, the conventional wisdom is that if you shorten the treatment you can promote the selection of resistant bacteria. Generally speaking there is a minimum inhibitory concentration (MIC) at which they inhibit bacterial growth which is dependent on the strain, but can also be influenced by their growth condition (in the lab standardized media are used to measure MIC, which might not be exactly the same in the body).

Now if the effective concentration of the compound drops below MIC, the effects are actually a little bit weird. If you look at defined cultures, e.g. mixing non-resistant with resistant bacteria, you still see a selective effect. But if you take a more complex sample, say fecal cultures or wastewater, the studies have been quite mixed whether there is a selective pressure (and/or there are other factors that would override it). It is fairly fascinating, actually.

[guidoLamoto]

Tetracycline oxidizes and becomes toxic with age, although it's rarely prescribed anymore. I'm not sure if the newer minocycline, doxycycline etc forms show the same thing. (Most drugs don't generally deteriorate significantly with age-- although ASA & NTG are notable exceptions, oxidizing and losing potency rapidly (weeks) once the bottle is opened.

The problem of antibiotic resistance and short courses of treatment is more theoretical than practical. Every time an antibiotic is used, the  pressure is for an increase in the gene frequency of resistant alleles in the population of surviving bugs.....Resistance is, after all, a phenomenon of neo-Darwinian evolution, not Lamarckian.

The population curve of a bug being treated shows an exponential decay over time, so, for a short course, a larger surviving population remains at the end of the course...but the survivors, no matter how few after even a longer course, have as much time as they need to re-populate... The med can't give 100% mortality-- It's purpose is to cut down the population of invaders enough that the natural immune response will finally polish them all off.--Resistance actually occurs out in the environment, not so much in the patient, when the free-living bugs are exposed to the "spillage" of the antiobiotic and the final "mop up operation" of the immune system is not available.

Edited December 3, 2023 by guidoLamoto