Medication Guide: Enrofloxacin / Baytril

Enrofloxacin / Baytril

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Brand

Baytril

Availability

Tablets: 5.7 mg, 22.7 mg, 68 mg, & 136 mg

Can be made into suspension.

Also comes as 22.7 mg/mL in 20 mL vials, or 5% solution in 20 mL vials for injection.

Pharmacology

Enrofloxacin, a third generation fluoroquinolone, is a broad-spectrum, bactericidal antibiotic. Its activity is concentration dependent. The mechanism of action is to inhibit bacterial DNA-gyrase, prevent DNA supercoiling and synthesis.

It has activity against some Gram-positive aerobes and a wide range of Gram-negative bacilli and cocci, which include klebsiella, pseudomonas, salmonella, and other organisms such as mycoplasma, staphylococci and chlamydia.

Because the fluoroquinolones have shown variable activity against most Streptococci, as well as weak activity against many anaerobic bacteria, they are not generally recommended for use in treating these types of infections.

When taken orally enrofloxacin is well absorbed, and although the presence of food in the stomach may delay rate it does not seem to effect its absorption capability.

Enrofloxacin is well distributed throughout the body, and can be found in small concentrations in the cerebral spinal fluid. About 30-40% of the drug is metabolized to the human approved drug, ciprofloxacin.

Enrofloxacin is eliminated by both renal and hepatic mechanisms, as well as in breast milk.

The quinolone class of drugs have been shown to produce erosions of cartilage in weight bearing joints and other signs of arthropathy in immature animals of various species.

The use of fluoroquinolones has not been recommended for initial treatment in pregnant and nursing does, or rats under 4 months due to the risks of cartilage abnormalities (Egerbacher et al., 2000), however, in cases where other antibiotics are not helping, or if the infection is deemed severe, the benefit of using fluoroquinolones (alone or in combination with other compatible antimicrobials) may in fact outweigh the risks.

Studies reported by Bayer, in their insert for enrofloxacin, reveal no evidence of carcinogenic or teratogenic effects in rats at higher doses of up to 50mg/kg.

Refer to Baytril insert by Bayer: http://www.bayerdvm.com/products/baytril/baytril.cfm

Indications

Useful in: respiratory infections, urinary tract infections, and soft tissue injury.

Drug Interactions or Contraindications

Antacids and dairy products containing Magnesium, Calcium, and Aluminum may prevent absorption of enrofloxacin. It is suggested to separate dosing from any of these products by 2 hours.

Theophylline blood levels may be increased when used with enrofloxacin.

Probenecid blocks tubular secretion of enrofloxacin and may cause an increase in its blood level and half life.

Synergism can occur when aminoglycosides, cephalosporins, and extended-spectrum penicillins are used with fluorinated quinolones such as enrofloxacin.

Adverse Reactions

CNS: restlessness, seizures

GI: decreased appetite, diarrhea

GU: crystalluria

Skin: Can cause tissue damage when given undiluted in IM or SQ injections in pet rats.

Other: itching

Dosage Recommendations

*Note: If choosing to use Baytril 10%, keep in mind it has a concentration of 100 mg per 1 mL. Also, because the 10% concentration can be so caustic to tissue it must be diluted for all routes.

5 mg/kg to 10 mg/kg , PO , IM , q12hr ¹ ²⁶ ²⁷ ²⁸; anywhere from 5 to 30 days (injectable form may be given orally). May be combined with doxycycline for treatment of mycoplasma. ²⁶ ²⁷

5 mg/kg to 20 mg/kg , PO , SQ , q24hr ²⁶ ²⁷

5 mg/lb , PO , BID (as recommended on RMCA Drug Chart) ⁴

Baytril 2.27% =.20 mL/lb 14 to 30 days (as recommended on RMCA Drug Chart) ⁴

2.5 mg/kg to 10 mg/kg , PO , q12hr ²

Per Rat Health Care by Debbie Ducommun:”Best reserved for older animals and more severe infection”, Baytril 10mg/lb (20 mg/kg) , PO or SQ , BID ³

Enrofloxacin in Treatment Regimen

The following dosage guideline, for use of enrofloxacin in rats with serious respiratory infection suspected to have Mycoplasma as the pathogen, is recommended by Dr. Michael Hutchinson, DVM; Animal General, Cranberry Township, PA. ¹⁸ , and is based on his experience treating rats and current literature:

Treatment is initiated early, and aggressively, starting with 15 mg/kg for 10 days followed by assessment of the rat’s progress, and may be continued at that dose based on veterinary discretion.

For repeated respiratory infection unresponsive to enrofloxacin alone or when serious to advanced lung infection is present, treatment regimen incorporating enrofloxacin (Baytril) 15 mg/kg , PO , BID ,along with doxycycline, nebulized agents (Gentocin and albuterol), and dexamethasone can be initiated. For information on Dr.Hutchinson’s treatment regimen see articles: Mycoplasma or Pneumonia in the Health section of the Rat Guide.

Because Mycoplasma is probably never eliminated entirely from the airways, it often becomes necessary to use pulse antibiotic therapy (long term, intermittent, dosing), or a continuing maintenance schedule of antibiotics for rats with chronic Mycoplasmosis.

Dr. Hutchinson has had some success with the long term, maintenance dosing of enrofloxacin 15 mg/kg BID PO (or in the presence of renal disease 8 mg/kg to 10 mg/kg BID) in conjunction with doxycycline 5 mg/kg BID PO, and based on his experience no discernible side effects have been noted.

For appropriate dosing in pulse antibiotic therapy for chronic illness, discuss with veterinarian

Note: see warning for young, pregnant or nursing rats in Pharmacology section above.

Considerations

Because enrofloxacin may cause skin ulceration at the injection site, when giving SQ, it is recommended to dilute the injectable solution with NaCl or LRS. ¹
Be sure to keep animals well hydrated to prevent crystalluria (formation of crystals in urine).
Reconstituted suspension from tablets should be kept refrigerated and has a 14 day expiration time.
Enrofloxacin can be used simultaneously with doxycycline in the treatment of Mycoplasma. ²⁶ ²⁷
Also, in treating suspected polymicrobial infections, where a broader coverage may be needed, synergistic or combination drugs may be used. The following drugs may be seen used simultaneously with enrofloxacin: aminoglycosides (e.g., amikacin or gentamicin), or aminopenicillins (e.g., amoxicillin or ampicillin), or third generation cephalosporins, or clindamycin, or doxycycline (for mycoplasma), or metronidazole. ¹
Please note that it is imperative to discuss the changing or adding of any medications during your rat’s treatment with your veterinarian to prevent future resistance of microbes to the drugs prescribed.

Reference

Egerbacher, M., Seiberl, G., Wolfesberger, B., & Walter, I. (2000). Ciprofloxacin causes cytoskeletal changes and detachment of human and rat chondrocytes in vitro. Arch Toxicol, 73(10-11), 557-63. Retrieved December 20, 2008, from the PubMed database.