Enrofloxacin
**Enrofloxacin** is a broad-spectrum, concentration-dependent **fluoroquinolone antibiotic** developed exclusively for veterinary use. * **Spectrum of Activity**: Highly effective against a wide range of Gram-negative bacilli (e.g., *Pseudomonas aeruginosa*, *E. coli*, *Klebsiella*, *Salmonella*) and many Gram-positive cocci (e.g., *Staphylococcus* spp., including methicillin-resistant strains). * **Limitations**: It has weak activity against anaerobes and variable efficacy against *Streptococcus* spp. * **Clinical Pearl**: Enrofloxacin is highly lipophilic, allowing for excellent tissue penetration. It achieves therapeutic concentrations in difficult-to-reach sites such as the prostate, bone, cerebrospinal fluid (CSF), and intracellular compartments (e.g., inside macrophages), making it highly effective for deep-seated and intracellular infections.
Mecanismo: Enrofloxacin exerts its rapid bactericidal effect by targeting key bacterial enzymes involved in DNA replication and transcription: * Inhibits **DNA gyrase (Topoisomerase II)** → prevents the negative supercoiling of bacterial DNA required for replication. * Inhibits **Topoisomerase IV** → interferes with the separation of interlinked replicated DNA molecules. **Result**: Disruption of DNA synthesis → double-strand DNA breaks → rapid bacterial cell death within 20-30 minutes of exposure. > **Pharmacodynamic Pearl**: Enrofloxacin exhibits a significant **post-antibiotic effect (PAE)** for both Gram-negative and Gram-positive bacteria, meaning bacterial growth continues to be suppressed even after drug concentrations fall below the Minimum Inhibitory Concentration (MIC).
Dosificación por especie
- Susceptible infections · 5 mg/kg per day PO · PO · q24h or divided q12h · At least 2-3 days beyond cessation of clinical signs, max 30 days · Do not exceed 5 mg/kg/day due to risk of blindness.
- Hemoplasmosis · 5-10 mg/kg PO · PO · q24h · 14 days
- Susceptible infections · 5 mg/kg · SC · q24h · Not specified · Do not exceed 5 mg/kg/day due to risk of irreversible retinal blindness.
- Susceptible infections · 2.5 mg/kg · PO · q12h · Not specified · Do not exceed 5 mg/kg/day total.
- Susceptible infections · 5 mg/kg · PO · q24h · Not specified · Do not exceed 5 mg/kg/day total.
- Susceptible infections · 10-20 mg/kg PO, IM, SC · PO, IM, SC · q12h
- Susceptible infections in alpacas (Camelids) · 5 mg/kg SC or 10 mg/kg PO · SC, PO · q24h
- Susceptible infections · 5 mg/kg IV q24h; 5-7.5 mg/kg PO q24h · IV, PO · q24h · Use in horses is controversial. Only use in adults when other antibiotics are inappropriate.
- Susceptible respiratory infections · 7.5 mg/kg PO or IV · PO, IV · q24h
Vías de administración
Contraindicaciones
- Small and medium breed dogs 2 to 8 months of age (risk of cartilage damage)
- Large and giant breed dogs during their rapid-growth phase (may extend past 8 months)
- Patients hypersensitive to quinolones
- Foals (highly susceptible to arthropathic effects)
- Food-producing animals (extra-label use is strictly prohibited by the FDA)
- Dairy cattle or veal calves
- Growing dogs (<1 year of age; large-breed dogs <18 months of age)
- Cats <8 weeks of age
- Animals with known seizure disorders (relative contraindication)
Efectos adversos
- Gastrointestinal distress (vomiting, anorexia, diarrhea)
- CNS stimulation (seizures, depression, lethargy, nervousness, ataxia)
- Cartilage abnormalities in young, growing animals
- Ocular toxicity/blindness in cats (at doses >5 mg/kg/day)
- Crystalluria (especially in dehydrated patients)
- Hypersensitivity reactions
- Elevated hepatic enzymes
- Tissue damage or pain at injection site (especially SC)
- Irreversible retinal blindness (cats)
- Cartilage abnormalities (growing dogs)
- Gastrointestinal upset (vomiting, diarrhea, anorexia)
- CNS toxicity / seizures (especially at high doses or with NSAIDs)
Interacciones farmacológicas
- Antacids / Dairy Products (Mg++, Al+++, Ca++) · Cations bind to enrofloxacin and prevent its absorption; separate doses by at least 2 hours.
- Other Antibiotics (aminoglycosides, 3rd-gen cephalosporins, extended-spectrum penicillins) · Synergism may occur, though unpredictable against some bacteria like Pseudomonas aeruginosa.
- Cyclosporine · May exacerbate nephrotoxicity and reduce the metabolism of systemic cyclosporine.
- Flunixin · Increases the AUC and elimination half-life of both enrofloxacin and flunixin in dogs.
- Glyburide · Severe hypoglycemia is possible.
- Iron, Zinc (oral) · Decreased enrofloxacin absorption; separate doses by at least 2 hours.
- Methotrexate · Increased methotrexate levels possible, resulting in toxicity.
- Nitrofurantoin · May antagonize the antimicrobial activity of fluoroquinolones; concomitant use is not recommended.
- Phenytoin · May alter phenytoin blood levels.
- Probenecid · Blocks tubular secretion of ciprofloxacin (active metabolite), increasing its blood level and half-life.
- Quinidine · Increased risk for cardiotoxicity.
- Sucralfate · May inhibit absorption of enrofloxacin; separate doses by at least 2 hours. · major
Monitorización
- Clinical efficacy (resolution of infection)
- Adverse effects (GI upset, CNS signs)
- In cats: Monitor closely for mydriasis (dilated pupils) and/or retinal changes/vision loss
- Vision and pupillary light reflexes in cats
- Neurological status, especially in patients with a history of seizures
- Joint pain or lameness in young animals (if inadvertently administered)
Sobredosis
Acute overdoses in **dogs** typically result in gastrointestinal signs (anorexia, vomiting). Dogs receiving 10X the labeled dose for 14 days developed only vomiting and anorexia. However, extreme overdoses (25X the labeled rate for 11 days) resulted in death. In **cats**, overdoses can be severe and irreversible. Doses of 20 mg/kg or more can cause **retinopathy, blindness, and seizures**. Common signs of toxicity reported to poison control include vomiting, lethargy, seizures, anorexia, depression, and diarrhea in dogs; and seizures and recumbency in cats.
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