Baytril Tablets (150 mg) (Canada)

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Baytril Tablets (150 mg)

This treatment applies to the following species:
Manufacturer: Bayer

(enrofloxacin)

Antimicrobial Tablets and Injectable Solution

FOR VETERINARY USE ONLY

DIN 02169428 - 50 mg/mL

DIN 02239524 - 15 mg

DIN 02239525 - 50 mg

DIN 02239526 - 150 mg

Description

Enrofloxacin is a synthetic chemo-therapeutic 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 Table 1). It is rapidly absorbed from the digestive tract, penetrating into all measured body tissues and fluids. (See Table 2). Tablets are available in three sizes (15.0, 50.0 and 150.0 mg enrofloxacin). Each mL of injectable solution contains: enrofloxacin 50 mg, n-butyl alcohol 30 mg, potassium hydroxide for pH adjustment and water for injection, q.s.

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

ACTIONS:

Microbiology: Enrofloxacin, a 4-fluoroquinolone compound, is bactericidal with activity against a broad spectrum of both Gram negative and Gram positive bacteria.

Fluoroquinolones elicit their bactericidal properties through interactions with two intercellular enzymes - DNA gyrase (DNA topoisomerase II) and DNA topoisomerase IV - which are essential for bacterial DNA transcription, synthesis and replication. It is believed that fluoroquinolones activity bind with DNA:ENZYME complexes and thereby inhibit the essential processes catalyzed by the enzymes (DNA supercoiling and chromosomal decatenation)1. The ultimate outcome of fluoroquinolone intervention is DNA fragmentation and bacterial cell death.2,3

Enrofloxacin minimum inhibitory concentrations (MICs) were determined for canine and feline bacterial isolates originating from natural infections of the dermal, gastrointestinal, respiratory and urinary systems. Seven hundred and thirty eight (738) isolates were collected from 14 different diagnostic laboratories located throughout the United States. Bacterial identity was confirmed by colony morphology, Gram stain and biochemical testing; for mycoplasmas, identity was confirmed by colony morphology and Dienes stain. The in vitro susceptibilities of all bacterial and mycoplasma isolates were determined by enrofloxacin microbroth dilution methods and the resultant enrofloxacin MIC50 and MIC90 values are presented in Table 1. In vitro susceptibility testing was performed in accordance with guidelines established by the National Committee for Clinical Laboratory Standards (NCCLS; Document M31-P, Volume 14, November 20).

Table 1 - MIC Values for Enrofloxacin Against Canine and Feline Pathogens (Diagnostic laboratory isolates, 1997)

Organism

Isolates

MIC50 (µg/ml)

MIC90 (µg/ml)

Bordetella spp.

25

0.5

0.5

Enterococcus spp.

40

1

2

Escherichia coli

138

0.03

0.06

Klebsiella pneumoniae

32

0.06

0.12

Mycoplasma spp.

76

0.25

0.5

Pasteurella spp.

16

0.015

0.03

Proteus spp.

88

0.12

0.25

Pseudomonas aeruginosa

69

1

8

Salmonella spp.

15

0.06

0.25

Staphylococcus intermedius

119

0.12

0.25

Staphylococcus spp.

120

0.12

0.25

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 1 and 2) 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 at 2.5 mg/kg is given in Table 2.

Table 2 - Blood Fluid/Tissue distribution of Enrofloxacin in Dogs and Cats:

Single Oral Dose is 2.5 mg/kg (1.13 mg/lb)

Body Fluids (mcg/mL)

Post-treatment Enrofloxacin Levels

Canine (n=2)

Feline (n=4)

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

Other

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

Pharmacokinetics: In dogs, the absorption and elimination characteristics of the oral formulation are linear (plasma concentrations increase proportionally with dose) when enrofloxacin is administered at up to 11.5 mg/kg, twice daily.4 Approximately 80% of the orally administered dose enters the systemic circulation unchanged. The eliminating organs, based on the drug's body clearance time, can readily remove the drug with no indication that the eliminating mechanisms are saturated. The primary route of excretion is via the urine. The absorption and elimination characteristics beyond this point are unknown. In cats, no oral absorption information is available at other than 2.5 mg/kg, administered orally as a single dose. Saturable absorption and/or elimination processes may occur at greater doses. When saturation of the absorption process occurs, the plasma concentration of the active moiety will be less than predicted, based on the concept of dose proportionality.

Following an oral dose in dogs of 2.5 mg/kg (1.13 mg/lb), enrofloxacin reached 50% of its maximum serum concentration in 15 minutes and peak serum level was reached in one hour. The elimination half-life in dogs is approximately 2 1/2-3 hours at that dose, while in cats it is greater than 4 hours. In a study comparing dogs and cats, the peak concentration and the time to peak concentration were not different.

A graph indicating the mean serum levels following a dose of 2.5 mg/kg (1.13 mg/lb) in dogs (oral and intramuscular) and cats (oral) is shown in Figure 1.

Figure 1 - Serum Concentrations of Enrofloxacin Following a Single Oral or Intramuscular Dose at 2.5 mg/kg in Dogs and a Single Oral Dose at 2.5 mg/kg in Cats.

Breakpoint: Based on in-vitro susceptibility, pharmacokinetics and clinical response, the following breakpoints are recommended for canine and feline isolates. These breakpoints have been approved by the National Committee for Clinical Laboratory Standards (NCCLS) and are published in NCCLS document M-31:

Zone Diameter (mm)

MIC µg/mL

Interpretation

≥ 23

≤ 0.5

Susceptible (S)

18 - 22

1 - 2

Flexible Label (F)

≤ 17

≥ 4

Resistant (R)

A report of ‘Susceptible’ indicates that the pathogen is likely to be inhibited by plasma levels generally attained with the lower end of the dose range (2.5 mg/kg BW twice daily or 5.0 mg/kg BW once daily). A report of ‘Flexible Label’ indicates that the pathogen is likely inhibited by plasma levels generally attained with adherence to the principles of FDA-approved Professional Flexible Labeling in dogs. With enrofloxacin, conditions due to ‘F’ bacteria can be treated successfully by administration of an intermediary dose within the lower (>5.0 mg/kg BW once daily) and upper (≤ 20 mg/kg BW once daily) limits of the approved flexible dose range. Determination of the precise dosage is based upon a careful assessment of the interrelationships amongst host (immunocompetency, stress, site of injection, etc.), pathogen (virulence, MIC, emerging resistance, etc.) and chemotherapeutic (dose-dependant vs time-dependant efficacy, postantibiotic effects, toxicity etc.). A report of ‘Resistant’ indicates that the pathogen is unlikely to be inhibited by plasma levels attained with administration of the highest approved dose (20 mg/kg BW once daily) and alternative antimicrobial therapy should be selected.

Standardized procedures require the use of laboratory quality control organisms for both standardized disk diffusion assays and standardized dilution assays. The 5 µg enrofloxacin disk should give the following zone diameters and enrofloxacin powder should provide the following MIC values for reference strains. The indicated ranges for quality control organisms are NCCLS-approved.

QC Strain

Zone Diameter (mm)

MIC µg/mL

E. coli ATCC 25922

32 - 40

0.008 - 0.03

P. aeruginosa ATCC 27853

15 - 19

1 - 4

S. aureus ATCC 25923

27 - 31

. . .

S. aureus ATCC 25913

. . .

0.03 - 0.12

Baytril Tablets (150 mg) Indications

Dogs and Cats: Baytril (brand of enrofloxacin) Antibacterial Tablets and Injectable Solution are indicated for the management of diseases in dogs and cats associated with bacteria susceptible to enrofloxacin.

EFFICACY CONFIRMATION:

Dogs: Clinical efficacy was established in dermal infections (wounds and abscesses) associated with susceptible strains of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Staphylococcus intermedius; respiratory infections (pneumonia, tonsillitis, rhinitis) associated with susceptible strains of Escherichia coli and Staphylococcus aureus; and urinary cystitis associated with susceptible strains of Escherichia coli, Proteus mirabilis, and Staphylococcus aureus.

Cats: Clinical efficacy was established in dermal infections (wounds and abscesses) associated with susceptible strains of Pasteurella multocida, Staphylococcus aureus, and Staphylococcus epidermidis.

Contraindications

Enrofloxacin is contraindicated in dogs and cats known to be hypersensitive to quinolones.

Dogs: Based on the studies discussed under the section on Animal Toxicology, the use of enrofloxacin is contraindicated in small and medium breeds of dogs during the rapid growth phase (between 2 and 8 months of age). The safe use of enrofloxacin has not been established in large and giant breeds during the rapid growth phase. Large breeds may be in this phase for up to one year of age and the giant breeds for up to 18 months. In clinical field trials utilizing a daily oral dose of 5.0 mg/kg, there were no reports of lameness or joint problems in any breed. However, controlled studies with histological examination of the articular cartilage have not been conducted in the large or giant breeds.

Adverse Reactions

Dogs: Two of the 270 (0.7%) dogs treated with Baytril® (brand of enrofloxacin) Tablets at 5.0 mg/kg per day in the clinical field studies exhibited side effects, which were apparently drug related. These two cases of vomition were self-limiting.

Post Approval Experience: The following adverse experiences, although rare, are based on voluntary post-approval adverse drug experience reporting. The categories of reactions are listed in decreasing order of frequency by body system.

Gastrointestinal: Anorexia. diarrhea, vomiting, elevated liver enzymes

Neurologic: ataxia, seizures

Behavioral: Depression, lethargy, nervousness

Cats: No drug-related side effects were reported in 124 cats treated with Baytril® (brand of enrofloxacin) Tablets at 5.0 mg/kg per day for 10 days in clinical field studies.

Post Approval Experience: The following adverse experiences, although rare, are based on voluntary post-approval adverse drug experience reporting. The categories of reactions are listed in decreasing order of frequency by body system.

Ocular: Loss of vision, retinal abnormalities (retinal degeneration, retinal atrophy, attenuated retinal vessels, and hyperreflective tapeta have been reported), mydriasis

Gastrointestinal: vomiting, anorexia, elevated liver enzymes, diarrhea

Neurologic: ataxia, seizures

Behavioral: Depression, lethargy, vocalization, aggression

ANIMAL TOXICOLOGY:

Dogs: Adult dogs receiving enrofloxacin orally at a daily dosage rate of 52 mg/kg for 13 weeks had only isolated incidences of vomition and inappetence. Adult dogs receiving the tablet formulation for 30 consecutive days at a daily treatment of 25 mg/kg did not exhibit significant clinical signs nor were there effects upon the clinical chemistry, hematological or histological parameters. Daily doses of 125 mg/kg for up to 11 days induced vomition, inappetence, depression, difficult locomotion and death while adult dogs receiving 50 mg/kg/day for 14 days had clinical signs of vomition and inappetence.

Adult dogs dosed intramuscularly for three treatments at 12.5 mg/kg followed by 57 oral treatments at 12.5 mg/kg, all at 12 hour intervals, did not exhibit either significant clinical signs or effects upon the clinical chemistry, hematological or histological parameters.

Oral treatment of 15 to 28 week old growing puppies with daily dosage rates of 25 mg/kg has induced abnormal carriage of the carpal joint and weakness in the hindquarters. Significant improvement of clinical signs is observed following drug withdrawal. Microscopic studies have identified lesions of the articular cartilage following 30 day treatments at either 5, 15 or 25 mg/kg in this age group. Clinical signs of difficult ambulation or associated cartilage lesions have not been observed in 29 to 34 week old puppies following daily treatments of 25 mg/kg for 30 consecutive days nor in 2 week old puppies with the same treatment schedule.

Tests indicated no effect on circulating microfilariae or adult heartworms (Dirofilaria immitis) when dogs were treated at a daily dosage rate of 15 mg/kg for 30 days. No effect on cholinesterase values was observed.

No adverse effects were observed on reproductive parameters when male dogs received 10 consecutive daily treatments of 15 mg/kg/day at 3 intervals (90, 45 and 14 days) prior to breeding or when female dogs received 10 consecutive daily treatments of 15 mg/kg/day at 4 intervals; between 30 and 0 days prior to breeding, early pregnancy (between 10th & 30th days), late pregnancy (between 40th & 60th days), and during lactation (the first 28 days).

Cats: Cats in age ranges of 3 to 4 months and 7 to 10 months received daily treatments of 25 mg/kg for 30 consecutive days with no adverse effects upon the clinical chemistry, hematological or histological parameters. In cats 7-10 months of age treated daily for 30 consecutive days, 2 of 4 receiving 5 mg/kg, 3 of 4 receiving 15 mg/kg, 2 of 4 receiving 25 mg/kg and 1 of 4 nontreated controls experienced occasional vomition. Five to 7 month old cats had no side effects with daily treatments of 15 mg/kg for 30 days, but 2 of 4 animals had articular cartilage lesions when administered 25 mg/kg/day for 30 days.

Doses of 125 mg/kg for 5 consecutive days to adult cats induced vomition, depression, incoordination and death while those receiving 50 mg/kg for 6 days had clinical signs of vomition, inappetence, incoordination and convulsions, but they returned to normal.

Enrofloxacin was administered to thirty-two (8 per group), six to eight month-old cats at doses of 0, 5, 20, and 50 mg/kg once a day for 21 consecutive days. There were no adverse effects observed in cats administered 5 mg/kg body weight of enrofloxacin. The administration of enrofloxacin at 20 mg/kg body weight or greater, resulted in mild to severe retinal degeneration, abnormal electroretinograms, and microscopic changes in the retina.

DRUG INTERACTIONS:

Compounds that contain metal cations (e.g., aluminum, calcium, iron, magnesium) may reduce the absorption of some quinolone-class drugs from the intestinal tract. Concomitant therapy with other drugs that are metabolized in the liver may reduce the clearance rates of the quinolone and the other drug.

Dogs: Enrofloxacin has been administered to dogs at a daily dose rate of 10 mg/kg concurrently with a wide variety of other health products including anthelmintics (praziquantel, febantel, sodium disophenol), insecticides (fenthion, pyrethrins), heartworm preventatives (diethylcarbamazine) and other antibiotics (ampicillin, gentamicin sulfate, penicillin, dihydrostreptomycin). No incompatibilities with other drugs are known at this time.

Cats: Enrofloxacin was administered at a daily dose rate of 5 mg/kg concurrently with anthelmintics (praziquantel, febantel), an insecticide (propoxur) and another antibacterial (ampicillin). No incompatibilities with other drugs are known at this time.

Baytril Tablets (150 mg) Caution

Quinolone-class drugs should be used with caution in animals with known or suspected Central Nervous System (CNS) disorders. In such animals, quinolones have, in rare instances, been associated with CNS stimulation which may lead to convulsive seizures.

Quinolone-class drugs have been associated with cartilage erosions in weight-bearing joints and other forms of arthropathy in immature animals of various species.

In rare instances, use of this product in cats has been associated with retinal toxicity. Safety in breeding or pregnant cats has not been established.

Warnings:

Keep out of reach of children.

Baytril Tablets (150 mg) Dosage And Administration

Dogs: The dose range of Baytril (brand of enrofloxacin) Tablets in dogs is 5 to 20 mg/kg (2.27-9.07 mg/lb) of body weight, either as a single dose or divided into two (2) equal daily doses administered at twelve (12) hour intervals. Selection of a dose within this range should be based on clinical experience, the severity of disease, and susceptibility of the pathogen.

Animals which receive doses in the upper-end of the dose range should be carefully monitored for clinical signs that may include inappetence, depression, and vomition. For dogs, Baytril Injectable Solution may be used initially as an intramuscular dose at 2.5 mg/kg.

Cats: The dose of Baytril® (brand of enrofloxacin) Tablets in cats is 5 mg/kg (2.27 mg/lb) of body weight, either as a single dose or divided into two (2) equal daily doses administered at twelve (12) hour intervals. In rare instances, use of this product in cats has been associated with retinal toxicity. Based on post approval experience, cats should be carefully monitored for clinical signs of mydriasis and/or changes in the retina.

TABLETS:

Dogs & Cats: The duration of treatment should be selected based on clinical evidence. Generally, administration of Baytril Tablets should continue for at least 2-3 days beyond cessation of clinical signs. For severe and/or complicated infections, more prolonged therapy, up to 30 days, may be required. If no improvement is seen within five days, the diagnosis should be reevaluated and a different course of therapy considered.

The lower limit of the dose range in dogs and the daily dose for cats was based on efficacy studies in dogs and cats where enrofloxacin was administered at 2.5 mg/kg twice daily. Target animal safety and toxicology studies were used to establish the upper limit of the dose range and treatment duration.

INJECTABLE SOLUTION:

Dogs Only: The optimum dose of Baytril (enrofloxacin) has been established at 2.5 mg/kg (1.13 mg/lb) of body weight administered twice daily (every 12 hours). Baytril Injectable Solution (2.27% or 5%) may be used in dogs twice daily (every 12 hours) by intramuscular injection for up to three days (6 doses). Different injection sites must be used for each treatment. Twelve hours following the last injection dosing should continue with Baytril Tablets given once daily for 2-3 days beyond the cessation of clinical signs. Total treatment with Baytril should not exceed 30 days. If no improvement is not seen within five days, the diagnosis should be re-evaluated and a different course of therapy considered.

Storage

Protect injectable from direct sunlight. Do not freeze.

How Supplied

Code Number

Baytril Injectable Solution
50 mg/mL Vial Size

 

180049

50 mL

Code Number

Baytril Tablets Tablet Size

Tablets/Bottles

1368892

15 mg

100 Single Scored

1368914

50 mg

100 Single Scored

1407235

50 mg

250 Single Scored

1368949

150 mg

50 Single Scored

1368965

150 mg

250 Single Scored

References

1 Hooper DC and Wolfson JS. Mechanisms of quinolone action and bacterial killing, in Quinolone Antimicrobial Agents. Washington DC, American Society for Microbiology, 2nd ed., 1993, 53-75.

2 Gootz TD and Brightly KE. Fluoroquinolone antibacterials: sar. mechanism of action, resistance and clinical aspects. Medicinal Research Reviews 1996; 16(5): 433-486.

3 Drlica K and Zhoa X. DNA gyrase, topoisomerase IV and the 4- quinolones. Microbiology and Molecular Biology Reviews 1997; 61(3): 377-392.

4 Walker RD et al, Pharmacokinetic evaluation of enrofloxacin administered orally to healthy dogs. American Journal of Veterinary Research 1992; 53(12): 2315-2319.

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® Baytril, Bayer and the Bayer Cross are registered trademarks of Bayer AG, used under license.

™ trademarks of Bayer HealthCare LLC, used under license.

Bayer Inc., 77 Belfield Road, Toronto, Ontario M9W 1G6

Phone: 1 800-622-2937

NAC No.: 12230071

BAYER HEALTHCARE
Animal Health Division, Bayer Inc.

77 BELFIELD ROAD, TORONTO, ON, M9W 1G6
Telephone:   416-248-0771 or 800-268-1331
Toll-Free:   800-62-BAYER
Order Desk:   800-387-9179
Order Desk Fax:   800-361-3306
Fax:   416-240-4918
Website:   www.animalhealth.bayer.ca
Every effort has been made to ensure the accuracy of the Baytril Tablets (150 mg) information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the Canadian product label or package insert.

Copyright © 2014 North American Compendiums. Updated: 2014-07-28

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