Pharmacotherapeutic group: Antibacterials for systemic use, quinolone and quinoxaline antibacterials, fluoroquinolones.
ATCvet code: QJ01MA90
Enrofloxacin is bactericidal in action with activity against Gram positive and Gram negative bacteria and mycoplasmas. The mechanism of action of the quinolones is unique among antimicrobials – they act primarily to inhibit bacterial DNA gyrase, an enzyme responsible for controlling the super coiling of bacterial DNA during replication. Resealing of the double standard helix is inhibited resulting in irreversible degradation of the chromosomal DNA. The fluoroquinolones also possess activity against bacteria in the stationary phase by an alteration of the permeability of the outer membrane phospholipid cell wall.
Susceptibility of selected target pathogens (MIC) is as follows:
-Pasteurella multocida: 0.03 mg/L;
-Escherichia coli: 0.03-0.06 mg/L;
-Staphylococcus pseudointermedius: 0.125 mg/L;
-Pseudomonas aeruginosa: 2.0 mg/L.
Susceptibility breakpoints are: sensitive ≤0.5 mg/L; intermediate 1-2 mg/L; resistant ≥4 mg/L.
Bacterial resistance to fluoroquinolones most commonly occurs by alteration of the target, DNA-gyrase, via mutation. Less commonly mutation occurs at the topoisomerase-IV target. Other mechanisms of resistance occur when bacteria decrease the ability of the drug to enter the cell or increase active transport out of the cell. Resistance is usually chromosomally developed and, therefore, remains after antimicrobial therapy ends. Cross-resistance of enrofloxacin with other fluoroquinolones can occur. Changes in levels of resistance to fluoroquinolones over time by Campylobacter and Salmonella species are being monitored because of their possible impact on human health.
The pharmacokinetics of enrofloxacin in dogs and cats are such that oral and parenteral administration leads to similar serum levels.
Enrofloxacin is rapidly absorbed after oral, intramuscular and subcutaneous administration. In the study performed with the product in cats, the dose of enrofloxacin administered in cats was 3.36 (±0.30) mg/kg. The corrected maximal plasma concentration was 1654.37± 247.92ng/mL and it was reached within 1.28(±0.58) h (Tmax). AUC was 8433.55(±1851.80) ng h/mL and the value of T1/2 was 3.75 h (harmonic mean).
Approximately 40% of the oral or intravenous enrofloxacin dose administered in dogs is metabolised to ciprofloxacin.
Maximal plasma concentration for ciprofloxacin in cats was 173.18±34.08 ng/mL. T max was 2.42±0.89 h and terminal half life was 4.88 h (harmonic mean).
Enrofloxacin possesses a high distribution volume. Tissue levels 2-3 times higher than that found in the serum, have been demonstrated in laboratory animals and target species. Organs in which high levels can be expected are lungs, liver, kidney, skin, bone and lymphatic system. Enrofloxacin also distributes into the cerebrospinal fluid, the aqueous humour and the foetus in pregnant animals.
The elimination of enrofloxacin is renal, primarily through glomerular filtration and tubular secretion.