Enrosite Flavored: Product Information

ENROSITE FLAVORED- enrofloxacin tablet


Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian.

Federal law prohibits the extralabel use of this drug in food-producing animals.


Enrofloxacin is a synthetic chemotherapeutic agent from the class of the quinolone carboxylic acid derivatives. It has antibacterial activity against a broad spectrum of Gram negative and Gram positive bacteria (See Tables I and II). It is rapidly absorbed from the digestive tract, penetrating into all measured body tissues and fluids (See Table III). Tablets are available in three sizes (22.7, 68.0 and 136.0 mg enrofloxacin).

CHEMICAL NOMENCLATURE AND STRUCTURAL FORMULA: 1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid.

Chemical Structure
(click image for full-size original)



Quinolone carboxylic acid derivatives are classified as DNA gyrase inhibitors. The mechanism of action of these compounds is very complex and not yet fully understood. The site of action is bacterial gyrase, a synthesis promoting enzyme. The effect on Escherichia coli is the inhibition of DNA synthesis through prevention of DNA supercoiling. Among other things, such compounds lead to the cessation of cell respiration and division. They may also interrupt bacterial membrane integrity.1

Enrofloxacin is bactericidal, with activity against both Gram negative and Gram positive bacteria. The minimum inhibitory concentrations (MICs) were determined for a series of 39 isolates representing 9 genera of bacteria from natural infections in dogs and cats, selected principally because of resistance to one or more of the following antibiotics: ampicillin, cephalothin, colistin, chloramphenicol, erythromycin, gentamicin, kanamycin, penicillin, streptomycin, tetracycline, triple sulfa and sulfa/trimethoprim. The MIC values for enrofloxacin against these isolates are presented in Table I. Most strains of these organisms were found to be susceptible to enrofloxacin in vitro but the clinical significance has not been determined for some of the isolates.

The susceptibility of organisms to enrofloxacin should be determined using enrofloxacin 5 mcg disks. Specimens for susceptibility testing should be collected prior to the initiation of enrofloxacin therapy.

TABLE I — MIC Values for Enrofloxacin Against Canine and Feline Pathogens (Diagnostic laboratory isolates, 1984)
Organisms Isolates MIC Range (mcg/mL)
Bacteroides spp. 2 2
Bordetella bronchiseptica 3 0.125-0.5
Brucella canis 2 0.125-0.25
Clostridium perfringens 1 0.5
Escherichia coli 5* ≤ 0.016-0.031
Klebsiella spp. 11* 0.031-0.5
Proteus mirabilis 6 0.062-0.125
Pseudomonas aeruginosa 4 0.5-8
Staphylococcus spp. 5 0.125

*Includes feline isolates.

The inhibitory activity on 120 isolates of seven canine urinary pathogens was also investigated and is listed in Table II.

TABLE II — MIC Values for Enrofloxacin Against Canine Urinary Pathogens (Diagnostic laboratory isolates, 1985)
Organisms Isolates MIC Range (mcg/mL)
E. coli 30 0.06-2.0
P. mirabilis 20 0.125-2.0
K. pneumoniae 20 0.06-0.5
P. aeruginosa 10 1.0-8.0
Enterobacter spp. 10 0.06-1.0
Staph. (coag. +) 20 0.125-0.5
Strep. (alpha hemol.) 10 0.5-8.0

Distribution in the Body: Enrofloxacin penetrates into all canine and feline tissues and body fluids. Concentrations of drug equal to or greater than the MIC for many pathogens (See Tables I, II and III) are reached in most tissues by two hours after dosing at 2.5 mg/kg and are maintained for 8-12 hours after dosing. Particularly high levels of enrofloxacin are found in urine. A summary of the body fluid/tissue drug levels at 2 to 12 hours after dosing at 2.5 mg/kg is given in Table III.

Table III — Body Fluid/Tissue distribution of Enrofloxacin in Dogs and Cats
Single Oral Dose = 2.5 mg/kg (1.13 mg/lb)
Post-treatment Enrofloxacin Levels
Canine (n = 2) Feline (n = 4)
Body Fluids (mcg/mL) 2 Hr. 8 Hr. 2 Hr. 12 Hr.
Bile 2.13 1.97
Cerebrospinal Fluid 0.37 0.10
Urine 43.05 55.35 12.81 26.41
Eye Fluids 0.53 0.66 0.45 0.65
Whole Blood 1.01 0.36
Plasma 0.67 0.33
Serum 0.48 0.18
Tissues (mcg/g) Hematopoietic System
Liver 3.02 1.36 1.84 0.37
Spleen 1.45 0.85 1.33 0.52
Bone Marrow 2.10 1.22 1.68 0.64
Lymph Node 1.32 0.91 0.49 0.21
Urogenital System
Kidney 1.87 0.99 1.43 0.37
Bladder Wall 1.36 0.98 1.16 0.55
Testes 1.36 1.10 1.01 0.28
Prostate 1.36 2.20 1.88 0.55
Ovaries 0.78 0.56
Uterine Wall 1.59 0.29 0.81 1.05
Gastrointestinal and Cardiopulmonary Systems
Lung 1.34 0.82 0.91 0.33
Heart 1.88 0.78 0.84 0.32
Stomach 3.24 2.16 3.26 0.27
Small Intestine 2.10 1.11 2.72 0.40
Large Intestine 0.94 1.10
Fat 0.52 0.40 0.24 0.11
Skin 0.66 0.48 0.46 0.17
Muscle 1.62 0.77 0.53 0.29
Brain 0.25 0.24 0.22 0.12
Mammary Gland 0.45 0.21 0.36 0.30
Feces 1.65 9.97 0.37 4.18
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