恩諾沙星
**恩諾沙星 (Enrofloxacin)** 是一種廣效、濃度依賴型的**氟喹諾酮類抗生素**，專為獸醫使用而開發。 * **抗菌譜**：對多種革蘭氏陰性桿菌（如綠膿桿菌、大腸桿菌、克雷伯氏菌、沙門氏菌）及許多革蘭氏陽性球菌（如葡萄球菌，包括抗甲氧西林菌株）具有高度療效。 * **限制**：對厭氧菌的活性較弱，對鏈球菌的療效不一。 * **臨床要點**：具有高度脂溶性，能提供極佳的組織穿透力，包括前列腺、骨骼、腦脊髓液及細胞內（如巨噬細胞內）等難以到達的部位，對於深層及細胞內感染非常有效。
作用機制: 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).
各物種劑量
- 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
給藥途徑
禁忌症
- 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)
不良反應
- 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)
藥物相互作用
- 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
監測
- 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)
過量
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.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。