Long term efficacy of expired antibiotic medication

[TubeDriver]

A 2006 report published in the Journal of Pharmaceutical Sciences summarized SLEP’s (the Shelf Life Extension Program is a program run by the government) findings from the previous 20 years. Below are the antibiotics included in the report.

You’ll notice that there’s quite a variation in extension times. If one lasts 10 years, that doesn’t mean they all will, by any stretch. If an antibiotic you’re curious about isn’t included in this list, you can’t make any assumptions. There’s even variability from lot to lot. One lot may last five years; another lot of the same medication may not.

One note: You may wonder what “powder” refers to in this list. That’s a powdered form of the drug, which pharmacists use to make injectable solutions. Also note that these antibiotics were stored under ideal conditions (cool, dry, dark place).


Extension Time (Mos.)
Antibiotic Dosage Form No. Lots Tested Mean Range
Amoxicillin sodium Tablets 21 23 22–23
Ampicillin Capsules 5 49 22–64
Ampicillin sodium Injection-solution 8 57 29–87
Cefazolin sodium Powder 10 82 63–110
Ceftriaxone sodium Powder 4 60 44*–69
Cefoperazone sodium Powder 4 46 25–57
Cefoxitin sodium Powder 10 24 24–55
Cephalexin Capsules 6 57 28–135
Cephaprin sodium Powder 13 74 50–114
Chloroquine HCl Injection-solution 4 64 27–98
Ciprofloxacin Suspension 7 32 25–40
Ciprofloxacin Tablets 242 55 12–142
Clindamycin phosphate Injection-solution 31 44 18–77
Doxycycline hyclate Capsules 13 50 37–66
Doxycycline hyclate Powder 31 27 14–52
Doxycycline hyclate Tablets 169 27 15–91
Erythromycine lactobinate Powder 4 60 38–83
Neomycin and polymyxin B sulfates and bacitracin zinc Ophthalmic ointment 5 28 12–40
Penicillin G Powder 15 49 22–95
Penicillin G benzathine Suspension 4 70 61–84
Penicillin G procaine Powder 7 70 67–72
Primaquine phosphate Tablets 12 55 41–80
Spectinomycin HCl Suspension 8 83 55–109
Sulfacetamide sodium Ophthalmic ointment 4 39 35–44
Sulfadiazine silver Cream 37 57 28–204
Sulfadozine and pyrimethamine Tablets 8 67 34–93
Sulfisoxazole Tablets 4 56 45–68
Tetracycline HCl Capsules 11 50 17–133

[LaurelLynn]

I'm just wondering about the tetracycline and doxycycline though? When I was a pharmacy technician my pharmacist had explicitly said these can become toxic past expiration.... they can possibly cause renal tubular acidosis?

A few vets I've worked with have also mentioned to not use those after expiration date for this reason although they are happy to give me other expired meds

[TubeDriver]

I don't know, perhaps Patti can comment?


I'm just wondering about the tetracycline and doxycycline though? When I was a pharmacy technician my pharmacist had explicitly said these can become toxic past expiration.... they can possibly cause renal tubular acidosis?

A few vets I've worked with have also mentioned to not use those after expiration date for this reason although they are happy to give me other expired meds

[HRT4SQRLS]

There is a lot of information published regarding expired tetracycline drugs. Doxycycline, which we would be more likely to use is a 'tetracycline class' antibiotic.

Supposedly, the tetracycline drugs degrade into nephotoxic products. Expired tetracycline has been linked with Fanconi syndrome which is a kidney disorder. Because of this association, the tetracycline class should not be used after the expiration date when they are most like to begin degrading.

Here's an interesting little tidbit I found today while getting some info for another question about expired antibiotics. Unfortunately, I couldn't post because it's in the Rehabbers forum. I can see it but not post. Anyway, I found some info that surprised me.

http://www.fda.gov/downloads/Drugs/EmergencyPreparedness/BioterrorismandDrugPreparedness/UCM462484.pdf

Doxycycline is in the Shelf Life Extension Program. (SLEP) This FDA memo extends the expiration date of specific lots #'s of doxycycline up to 4 years beyond the expiration date. This was very surprising to me, to say the least. This was a very recent memo (9/15) and it seems to contradict the warnings that have been in place.

As far as I'm concerned, I won't be using doxycycline beyond the expiration date. This info is TOO new so I won't be embracing it any time soon. I'll wait for the recall memo... OOPS ... about that 'Fanconi syndrome thing' ... :tilt

I replaced my expired doxycycline in December. The new batch expires in 1/2017... about a year. I am going to split this purchase with 2 other local squirrel peeps. I doubt I will use it, but by supplying 3 people with one purchase, it's not a big deal to replace it yearly. Others might consider this also.

I figure, why take a chance.