Vetdrugs 2.0Norfloxacin is an older fluoroquinolone antibacterial with a history of extra-label veterinary use. Reported applications include selected urinary, respiratory and skin infections caused by susceptible organisms. Its veterinary use has declined because other fluoroquinolones offer more favorable exposure profiles and stronger species-specific clinical experience.
Group
Fluoroquinolone antibacterial
Mechanism of Action
Norfloxacin inhibits bacterial DNA gyrase and topoisomerase-dependent DNA processing. Stabilization of enzyme–DNA cleavage complexes interferes with replication and chromosome organization, leading to bacterial death. Its effect is concentration dependent. The useful spectrum includes susceptible gram-negative bacilli and selected gram-positive organisms, with clinical activity determined by both susceptibility and achieved exposure.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Susceptible bacterial infection | 22 mg/kg | PO | Every 12 h | Do not use in: Growing animals |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Susceptible bacterial infection | 22 mg/kg | PO | Every 12 h | Do not use in: Growing animals |
Indications
- Historical or occasional extra-label treatment of susceptible bacterial urinary tract infections in companion animals.
- Treatment of selected susceptible respiratory, skin or soft-tissue infections where a supported regimen is used; veterinary clinical evidence is limited.
Contraindications
- Growing animals: risk of articular-cartilage injury.
- Use caution in seizure-prone patients or renal failure.
Interactions
- Aluminum, iron, calcium, zinc and sucralfate can reduce absorption through chelation.
Adverse effects
- Gastrointestinal upset, CNS toxicity and juvenile arthropathy.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Norfloxacin 400 mg | Tablet | 400 mg / tablet | PO |
| Norfloxacin ophthalmic solution 0.3% Sterile eye drops only; not an oral or injectable preparation. | Other | 3 mg / mL | TOPICAL |
Monitoring and Administration
Base treatment on susceptibility and clinical response. Avoid mixing with metal-containing solutions.
Sterile norfloxacin 0.3% eye drops are described for established susceptible gram-negative corneal infection; prophylactic perioperative ophthalmic use is not recommended for this indication. A numeric drop amount or application interval is not given.
Topical ocular fluoroquinolones can produce local irritation or hypersensitivity. Systemic retinal-toxicity observations for other fluoroquinolones are not treated as a measured norfloxacin eye-drop risk.