# Expired fenbendazole



## sbarbee54 (Jan 12, 2012)

Not true, my friends wife is a chemical engineer with a emphasis on pharmaceuticals and the strengths starts dropping after that date or shortly after...

Throw it out.


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## Darkblade48 (Jan 4, 2008)

It is hard to say - sometimes the drug may or may not work.

At the recommended dosage, the drug will be effective prior to the printed expiration date. However, afterwards, it may or may not work, depending on how much it has degraded, etc. There is no guarantee it will work, but sometimes, it might be OK, if it was stored in optimal conditions.

I have used (expired) antibiotic (discs) in the lab for KB testing, and they still showed the same MIC as brand new discs.


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## ravensgate (May 24, 2012)

If you talk to vets just about any vet will tell you with most dewormers (and some other meds) you have a year from the manufacturers expiration date. At least that's what my vets say and having a farm and house animals as well I use about 5 different vets Some strength will be lost but not total efficacy. With other products it varies though, like eye meds, some of them can lose strength some of them can GAIN strength after the expiration date.

Wouldn't bother me to use it but its cheap enough to go buy fresh if you're concerned.


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## Hobbes1911 (Mar 2, 2009)

According to regular biochemistry you will see some decline in dosage strength after the expiration date. Any chemical substance has a half-life and usually the expiration date is set such that with the half-life in mind, the effective dosage of the drug delivered will be the same before the expiration date. Afterwards, the strength decreases as the active compound degrades into different compounds that might not act in the same mechanism as the drug initially was intended to do. That's why there are expiration dates. Now, there will always be active drug around in the pill/paste/solution, whatever, but the point being it is now not at the same strength and the degradation products are starting to increase in concentration. To be safe, throw it. If you want to chance it, start at the regular dose and see what happens. My advice, especially for higher grade shrimps, don't chance it, for a tank where a couple of losses don't matter, try it.


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## Chulios66 (Jan 3, 2013)

I use expired water conditioner and so far I haven't seen any harm to this.


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