Antibiotic use in UTI's

Re: Antibiotic use in UTI's

John Flynn — Sun, 02 Feb 2014 19:06:42 GMT

OK, you all got me thinking, so have tried to dig deeper to see if I'm alone in considering oxytetracycline (OTC henceforth) for UTIs.

[quote user="Michael Woodhouse"]IIRC oxytet excreted via the gut so no advantage there.[/quote]

[quote user="Linda Filshie"]According to the BSAVA formulary oxytet is excreted unchanged via urine and bile.[/quote]

I can't find much on canine pharmacokinetics, but the little I found seemed to indicate that:

80% of OTC was eliminated unchanged in the urine after intra-arterial administration in beagles, and greater than 8% of OTC from oral dosing was eliminated in the urine (reflecting the presumed poor and variable bioavailability of oral administration of approx 10%). Dissertation Abstracts International, B 1983 Vol. 43 No. 12 pp. 3937

On the sensitivity front:

An RVC study into urine cultures found OTC to have an "impact Factor" [which if I've interpreted correctly higher is better for an in vitro sensitivity] of 59, which compared to other antibiotics which were also on the "first-line sensitivity testing", beats amoxiclav, ampicillin, cefuroxime and cephalexin, losing only to enrofloxacin and TMPS. Veterinary Record Volume: 173 Issue: 22 (2013-01-01) p. 549

[Obviously that study's findings do not translate easily into GP clinical prescribing, but it is interesting nonetheless]

Re: Antibiotic use in UTI's

James Laidlaw — Sat, 01 Feb 2014 23:35:02 GMT

I don't think I've used oxytet since stopping large animal work and going to the dark side of small animal only practice... (Possibly being mocked as a Kiwi in Australia for apparently pronouncing it oxy-tit may have discouraged me as well)

Re: Antibiotic use in UTI's

Linda Filshie — Sat, 01 Feb 2014 20:45:27 GMT

[quote user="Michael Woodhouse"]

IIRC oxytet excreted via the gut so no advantage there.

We stopped even stocking oxytet tabs as the pots of 1000 kept going OOD.

[/quote]

According to the BSAVA formulary oxytet is excreted unchanged via urine and bile. Apparently there is also (not well documented) evidence of dose related functional changes in renal tubules in several species, so I would guess you might want to avoid in your CRF beasts with concurrent UTIs. BSAVA manual also says OOD oxytet has been associated with severe tubular damage due to degradation products - a good reason to practice good pharmacy protocols!

Re: Antibiotic use in UTI's

Michael Woodhouse — Sat, 01 Feb 2014 19:44:01 GMT

We were taught at college to use amoxycillin as 1st line as it concentrates in urine and urine concentration becomes very much higher than plasma.

Dredging my brains on TMPS and I seem to remember issues with ion trapping, but I think it is excreted via the urinary tract.

IIRC oxytet excreted via the gut so no advantage there.

We stopped even stocking oxytet tabs as the pots of 1000 kept going OOD.