Difloxacin
Difloxacin hydrochloride
Also known as: Dicural · A-56619 · Abbott-56619 · Difloxacin HCl
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 5-10 mg/kg | PO | q24h | 2-3 days beyond the cessation of clinical signs (maximum 30 days) | 🌎 NA |
- Susceptible infections: Administer preferably on an empty stomach, unless GI upset occurs.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections (MIC ≤ 0.25 micrograms/mL) | 7.5 mg/kg | PO | q24h | — | 🌎 NA |
- Susceptible infections (MIC ≤ 0.25 micrograms/mL): Administer non-fasted. Appears safe and adequately absorbed, but further investigation is warranted. Unknown if it should be avoided in young, growing horses.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Difloxacin is a veterinary-labeled fluoroquinolone antibiotic primarily indicated for the treatment of susceptible bacterial infections in dogs.
Key Clinical Features:
- Renal Sparing: Unlike many other fluoroquinolones that rely heavily on renal clearance, difloxacin undergoes extensive hepatobiliary excretion (>80% eliminated in feces). This makes it uniquely advantageous for dogs with moderate to severe renal failure, as it is less likely to accumulate to toxic levels.
- Spectrum of Activity: It exhibits good efficacy against many gram-negative and gram-positive bacilli and cocci (e.g., Klebsiella, Staphylococcus, E. coli, Enterobacter, Campylobacter, Proteus, and Pasteurella).
- Limitations: It has weak activity against most anaerobes and is generally ineffective against Enterococcus spp. Some strains of Pseudomonas aeruginosa may also be resistant.
Clinical Pearl: Fluoroquinolones are concentration-dependent bactericidal drugs. Maximizing the peak concentration (Cmax) relative to the minimum inhibitory concentration (MIC) is crucial for clinical efficacy and preventing resistance.
Mechanism of action
Difloxacin is a concentration-dependent bactericidal agent.
- It actively enters the bacterial cell and targets DNA-gyrase (a type-II topoisomerase) and topoisomerase IV.
- Inhibition of these enzymes → prevents DNA supercoiling and uncoiling → halts DNA synthesis and transcription.
- The net result is rapid disruption of bacterial cell replication and subsequent cell death.
Safety & warnings
Contraindications
- Hypersensitivity to difloxacin or other quinolones
- Immature dogs during the rapid growth phase (2-8 months in small/medium breeds; up to 18 months in large/giant breeds)
- Cats (relative contraindication due to nausea/vomiting and unknown ophthalmic/retinal safety)
- Food-producing animals (extra-label use prohibited by federal law)
Adverse effects
- Anorexia
- Vomiting
- Diarrhea
- Cartilage abnormalities (arthropathies) in growing animals
- CNS stimulation or seizures (rare)
- Facial erythema and edema (at high doses)
- Weight loss (at high doses)
Precautions
Use with caution in animals with known or suspected CNS disorders (e.g., seizure disorders), as fluoroquinolones have rarely been associated with CNS stimulation and seizures. Use with caution in patients with hepatic insufficiency, renal insufficiency, or dehydration. Safety in breeding or pregnant dogs has not been established.
Drug interactions
May bind to difloxacin and prevent its absorption; separate doses by at least 2 hours.
Calcium content may decrease absorption; separate doses by at least 2 hours.
Unpredictable synergism may occur against some bacteria, particularly Pseudomonas aeruginosa.
May exacerbate nephrotoxicity and reduce the metabolism of systemic cyclosporine.
Severe hypoglycemia is possible.
Decreased difloxacin absorption; separate doses by at least 2 hours.
Increased methotrexate levels possible, resulting in toxicity.
May antagonize the antimicrobial activity of fluoroquinolones; concomitant use is not recommended.
Difloxacin may alter phenytoin blood levels.
May block tubular secretion and increase the blood level and half-life of difloxacin.
May inhibit absorption of difloxacin; separate doses by at least 2 hours.
Difloxacin may increase theophylline blood levels, potentially leading to toxicity.
Potential for increased anticoagulant effects.
Monitoring
- Clinical efficacy (resolution of infection)
- Gastrointestinal signs (appetite, vomiting, diarrhea)
- CNS signs (especially in patients with a history of seizures)
Pharmacokinetics
Half-life
Absorption
Well absorbed orally in dogs (bioavailability >80%) with peak serum levels occurring about 3 hours post-dosing. In horses, oral bioavailability is approximately 70%.
Distribution
Widely distributed. Volume of distribution (Vd) is 2.8-4.7 L/kg in dogs and ~1 L/kg in horses. Marginally bound to plasma proteins in dogs (16-52%).
Metabolism
Undergoes extensive hepatobiliary processing.
Elimination
Primarily eliminated via biliary excretion, with >80% of a dose eliminated in the feces. Only ~5% is excreted by the kidneys, though urine levels remain well above MICs for susceptible organisms for at least 24 hours.
Overdose
In dogs, doses up to 2.5X the maximum recommended dose (25 mg/kg) for 30 days did not cause overly significant adverse effects. Observed signs included facial erythema/edema, diarrhea, decreased appetite, and weight loss. Treatment should be supportive and symptomatic.
Available products
Formulations
- Oral tablets
- Oral suspension (compounded/investigational in horses)
Veterinary
- Difloxacin Oral Scored Tablets: 11.4 mg (single scored)
- Difloxacin Oral Scored Tablets: 45.4 mg (single scored)
- Difloxacin Oral Scored Tablets: 136 mg (double scored)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Commercially available tablets should be stored between 15-30°C (59-86°F) and protected from excessive heat.
Client information
Difloxacin is an antibiotic used to treat bacterial infections.
- Administration: It is best to give this medication on an empty stomach. However, if your dog vomits or acts sick after receiving it, you can give future doses with a small amount of food.
- Important Interactions: Do not give this medication at the same time as dairy products (like cheese or yogurt), antacids, or supplements containing iron, zinc, or calcium. These can bind to the drug and prevent it from working. Space them out by at least 2 hours.
- Completion of Therapy: Give the medication exactly as prescribed for the full length of time, even if your pet seems completely better. Stopping early can cause the infection to return and become harder to treat.
- Side Effects: Contact your veterinarian if your pet experiences severe diarrhea, loss of appetite, facial swelling, or any unusual neurological signs (like tremors or seizures).
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.