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Antimicrobial Agents
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Tablets: 100 mg, 250 mg, 500 mg (tablets may be crushed to make a suspension)
Injectable: 10 mg/mL vials (avoid giving by injection, in rats, if possible)


Ciprofloxacin, a second-generation1 fluoroquinolone, is a broad-spectrum, concentration dependent bactericidal antibiotic with significant post-antibiotic effect (meaning it lends itself to once-daily application of the total daily dose or pulse-dosing regimens where deemed appropriate). The mechanism of action is believed to inhibit bacterial DNA-gyrase, prevent DNA supercoiling and synthesis.

Ciprofloxacin is structurally related to enrofloxacin and has a similar spectrum of activity. Both of these antimicrobials have shown activity against some Gram-positive aerobes such as staphylococci, and a wide range of Gram-negative bacilli and cocci, which include klebsiella spp., pasteurella spp., pseudomonas spp., salmonella, and other organisms such as mycoplasma, and chlamydia.
Due to the fluoroquinolones variable activity against most streptococci, as well as their weak activity against many anaerobic bacteria, they are generally not recommended for use in treating infections where these types of microbes are present.

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

Both enrofloxacin and ciprofloxacin are well distributed throughout the body, and can be found in small concentrations in the cerebral spinal fluid.

Ciprofloxacin is a metabolite of enrofloxacin, and like enrofloxacin is eliminated by both renal and hepatic mechanisms, as well as in breast milk.

It is known that the quinolone class of drugs have been shown to produce erosions of articular cartilage in weight bearing joints, as well as producing other signs of arthropathy in immature animals of various species, including juvenile rats (Kashida et al., 1997). However, evidence of cartilage abnormalities appear to be dose related (high dosages over extended period).

It is also important to note that although the use of fluoroquinolones have not been recommended for initial treatment in pregnant and nursing does or juvenile rats (under 4 months) due to the risks of cartilage abnormalities (Egerbacher et al., 2000), 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.


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

Although ciprofloxacin may be used as a substitute when enrofloxacin is not available it should be noted that there are some pharmacologic differences. Notably that ciprofloxacin is less reliably absorbed than enrofloxacin.

Clinical Note

Effective drug of choice for pseudomonas.

Drug Interactions or Contraindications

Concurrent administration of a quinolone, including ciprofloxacin, with cation-containing GI products such as magnesium/aluminum antacids or sucralfate, or GI products containing calcium, iron, or zinc may reduce its absorption. 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 IM or SQ

Other:  itching

Dosage Recommendations

7 mg/kg to 20 mg/kg ; PO, or IM , q12hrs.  1 26 27 28


5 mg/kg to 20 mg/kg ; PO , q12-24hrs. 34


10 mg/kg; PO , q12hrs.  2 26


2.5 mg/lb to 5 mg/lb ; PO , BID (twice a day)  4

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


  • Store tablets in tight moist free container.
  • Dilute SQ injections with NaCl or LRS.  1
  • Injections may cause skin ulceration.
  • Be sure to keep animals well hydrated in order to prevent crystalluria (formation of crystals in urine).
  • Reconstituted suspension from tablets should be kept refrigerated and has a 14 day expiration time.
  • Ciprofloxacin can be used simultaneously with doxycycline in the treatment of Mycoplasma.

    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 ciprofloxacin: aminoglycosides (e.g., amikacin or gentamicin), or aminopenicillins (e.g., amoxicillin or ampicillin), or third generation cephalosporins, or clindamycin, 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.
  • 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.
  • Pallo-Zimmerman, L., Byron, J., & Graves, T. (July 2010). Fluoroquinolones: Then and Now. Vetlearn.com. Retrieved April 25, 2011, from www.vetlearn.com/Portals/0/PV0710_zimmerman_CE.pdf
  • Kashida Y, Kato M. Toxic effects of quinolone antibacterial agents on the musculoskeletal system in juvenile rats. Toxicol Pathol 1997;25:635-43. Retrieved 2011.

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