Marbocyl, Zeniquin


  • Zeniquin Tablets: 25 mg, 50 mg, 100 mg, 1200 mg
  • Marbocyl Tablets: 5 mg, 20 mg, 80 mg
  • Suspension: can be made from tablets.
  • Marbocyl Injectable: 200 mg powder for reconstitution gives 10 mg/ml when reconstituted (not as yet approved for use in USA).


Marbofloxacin, 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). While its mechanism of action is not completely understood it is believed to act by inhibiting bacterial DNA-gyrase, preventing DNA supercoiling and synthesis.

It has 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.

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 marbofloxacin is both rapidly and well absorbed. It has not been determined whether the absorption of marbofloxacin is affected when given with food.

Marbofloxacin, like other fluoroquinolones, is able to attain high concentrations within cells in many tissues. It crosses the placenta, is found in breast milk, and can also be found in small concentrations in the cerebral spinal fluid.

Marbofloxacin is eliminated unchanged in the urine, and bile/feces, with only a small percentage being metabolized in the liver.

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 appears 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 the pregnant and nursing doe 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.

The MSDS reported by Pfizer, for marbofloxacin, reveals no evidence of carcinogenic or teratogenic effects in rats.


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

Drug Interactions or Contraindications

  • Concurrent administration of a quinolone, including marbofloxacin, 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 marbofloxacin.
  • Probenecid blocks tubular secretion of marbofloxacin 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 marbofloxacin.

Adverse Reactions

CNS: restlessness, seizures

GI: decreased appetite, diarrhea

GU: crystalluria

Other: itching

Dosage Recommendations

2 mg/kg to 5 mg/kg, PO, SQ, IM, q24h  42


2 mg/kg to 5 mg/kg, PO, SQ, IM, q24hr  32 (anywhere from 5 to 30 days)


4 mg/kg, PO, SQ, q24hrs. (May give injectable orally)  34, 35, 41, 44

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.


  • Unlike enrofloxacin, marbofloxacin when given by injection does not appear to cause skin ulceration at the injection site.
  • Be sure to keep animals well hydrated to prevent crystalluria (formation of crystals in urine).
  • When 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 marbofloxacin: 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.
  • Store tablets at dry, room temperature in closed container.
  • Reconstituted suspension from tablets should be kept refrigerated and has a 14 day expiration time.
  1. Pallo-Zimmerman, L., Byron, J., & Graves, T. (July 2010). Fluoroquinolones: Then and Now. Retrieved April 25, 2011, from
  2. Committee for Veterinary Medicinal Products. (October 1999). Marbofloxacin: Summary Report 2. European Medicines Agency. Retrieved April 25, 2011, from
  3. 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.
  4. 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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