Enrofloxacin
(Baytril)
(for veterinary
information only)
BRAND NAME: BAYTRIL
Available in 22.7 mg, 68 mg and 136 mg tablets
BACKGROUND
Until penicillin came on the scene in the 1940s, our efforts to combat bacterial
infection were largely ineffective. As different antibiotics were developed,
different types of bacteria were conquered, yet one bacterial species remained
seemingly invincible: Pseudomonas aeruginosa. Eventually antibiotics (the
aminoglycoside class) were developed that could kill Pseudomonas but they
were available only as injectable products and had potential to cause significant
kidney damage if used too long. With these kinds of side effects and the
ability to treat Pseudomonas limited to hospitalized patients (where injections
could be given regularly), the battle with Pseudomonas was far from won.
A major breakthrough was the development of the fluoroquinolone class of
antibiotics (including enrofloxacin, its counterpart for human use ciprofloxacin,
and several others). These medications are active against many bacterial
types including Pseudomonas. They are available as tablets and are not associated
with the serious side effects that plagued the aminoglycoside group.
Fluoroquinolones act by deactivating bacterial enzymes necessary for the
transcription of DNA. DNA is very tightly coiled in order to fit inside a
cell. Segments to be used must be uncoiled by an enzyme called DNA gyrase.
The fluoroquinolone antibiotic deactivates DNA gyrase making the reading
of DNA impossible. The bacterial cell dies. Mammalian DNA gyrase is of a
completely different shape and remains unharmed.
USES OF THIS MEDICATION
This medication may be used in either dogs or cats to combat different types
of infections, especially those involving Pseudomonas. Enrofloxacin is also
active against Staphylococci, and thus is commonly used for skin infections.
SIDE EFFECTS
At approximately ten times the recommended dose vomiting and diarrhea may
be seen with this medication. At normal doses, this should not be seen. Dogs
with Pseudomonas ear infections require very high doses of enrofloxacin and
nausea may indeed become a problem.
In immature dogs (less than 8 months of age) damage to joint cartilage can
occur. This phenomenon is only seen in growing dogs and does not seem to
be a problem in cats. It is preferable not to use this medication in puppies
unless the severity of the infection present warrants it.
The use of enrofloxacin can produce crystals in urine. These crystals may
show up on a laboratory test thus it is important to be aware of this side
effect.
See retinal damage below regarding the recently described feline retinal
problem associated with enrofloxacin at higher doses.
INTERACTIONS WITH OTHER DRUGS
Sucralfate (a medication used to treat stomach ulcers) may bind enrofloxacin
and prevent it from entering the body. These medications should be given
at least 2 hours apart if they are used together.
Theophylline (an airway dilator) blood levels may be higher than usual if
this medication is used concurrently with enrofloxacin. The dose of theophylline
may need to be reduced.
If enrofloxacin is used with oral cyclosporine (an immunosuppressive medication
used for inflammatory bowel disease), the kidney damaging properties of cyclosporine
may become worse.
Medications or supplements containing iron, zinc, magnesium or aluminum will
bind enrofloxacin and prevent absorption into the body. Such medications
should be separated from enrofloxacin by at least 2 hours.
CONCERNS AND CAUTIONS
Enrofloxacin tablets are enteric coated to hide the drug's naturally bitter
taste. If the tablets are crushed for some reason, the bitter taste is more
readily apparent. Crushing tablets to put in an animal's food is unlikely
to be an effective way to administer enrofloxacin. Recently, Bayer has manufactured
an alternative called a flavor-tab that is much more palatable than the purple-colored
enteric coated tablets. The tan colored flavor-tabs are more easily crushed
and mixed in food.
Pseudomonas infections are especially common in ears. In this location, especially
high doses of enrofloxacin are needed to clear this infection. Expect to
give a lot of pills and be prepared for expense.
Enrofloxacin has toxic properties in humans. It is for veterinary use only.
Enrofloxacin should not be used in pregnant, or nursing pets or in immature
dogs unless the severity of the infection warrants it.
Enrofloxacin may lower the seizure threshold (meaning that it can facilitate
seizures). This is not a problem for normal animals but fluoroquinolones
are best not used in animals with known seizure disorders.
Retinal damage has been seen in cats when higher doses (such as might be
used to treat a Pseudomonas ear infection) are used. This reaction is not
common even with very high doses, but there is no way to predict which cats
will react. Blindness, temporary or permanent, can result. This reaction
has only been reported with enrofloxacin and not with other fluoroquinolones,
as it is theorized that the biochemical structure of enrofloxacin leads to
especially high concentrations in the feline eye (in other words, this reaction
is theoretically possible with any fluoroquinolones but enrofloxacin is especially
predisposed to causing this reaction).
We periodically receive e-mail asking about the urinary crystals that can
be produced with the use of enrofloxacin. Two chief questions are generally
asked.
1) Might enrofloxacin contribute to the development of struvite crystals
and thus exacerbate feline lower urinary tract disease (FUS)?
The answer is probably not. The type of urinary crystals associated with
enrofloxacin use is not struvite or even oxalate crystals; the crystals formed
would be enrofloxacin crystals. The relationship between crystals and feline
lower urinary tract disease is controversial as are the assorted treatments
commonly prescribed for the symptoms of this condition. There is simply no
universally accepted treatment for this condition and the condition is felt
to have many possible causes.
2) What references do we have that enrofloxacin causes urinary crystals?
Not only does enrofloxacin cause crystals; entire bladder stones can be formed
out of enrofloxacin. Granted, a urinary stone composed of enrofloxacin is
somewhat unusual but it is important to realize that enrofloxacin crystals
might be found in a urine sample of a patient on enrofloxacin and that these
crystals should be recognized as such.
Iatrogenic Disorders of the Urinary Tract--Treating our Treatments.ACVIM
1999, C.A. Osborne, D.J. Polzin, J. P. Lulich, S.J. Ross, F. Jacob, A. C.
O'Keefe.
Pharmacologic Treatment of Uroliths -- Cause or Cure.ACVIM 1998, C. Osborne,
J. Lulich, et. al.
Drug-Induced UrolithiasisOsborne, C.A., Lulich, J.P., Bartges, J.W. et al.
Veterinary Clinics of North America Small Animal Practice 29[1]:251-66, xiv
1999 Jan.
It is our policy
not to give dosing information over the Internet.
Date
Published: 1/1/2001
Copyright
2001 - 2007 by the Veterinary Information Network, Inc. All rights reserved.
This work was originally published by Veterinary Information
Network, Inc. (VIN) and is republished with VIN's permission.
