二氟沙星
二氟沙星（Difloxacin）是一種獸醫專用的**氟喹諾酮類抗生素**，主要用於治療犬隻的敏感性細菌感染。 **主要臨床特徵：** * **保護腎臟：** 與許多主要依賴腎臟清除的氟喹諾酮類藥物不同，二氟沙星經歷廣泛的肝膽排泄（超過80%由糞便排出）。這使其對於患有中度至重度腎衰竭的犬隻具有獨特優勢，較不易累積至毒性濃度。 * **抗菌譜：** 對許多革蘭氏陰性及陽性桿菌和球菌（如克雷伯氏菌、葡萄球菌、大腸桿菌、腸桿菌、彎曲桿菌、變形桿菌和巴斯德桿菌）具有良好的療效。 * **局限性：** 對大多數厭氧菌的活性較弱，且通常對腸球菌無效。部分綠膿桿菌菌株也可能具有抗藥性。 > **臨床要點：** 氟喹諾酮類是濃度依賴型殺菌藥物。相對於最低抑菌濃度（MIC），最大化峰值濃度（Cmax）對於臨床療效及預防抗藥性至關重要。
作用機制: 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.
各物種劑量
- Susceptible infections (MIC ≤ 0.25 micrograms/mL) · 7.5 mg/kg · PO · q24h · Administer non-fasted. Appears safe and adequately absorbed, but further investigation is warranted. Unknown if it should be avoided in young, growing horses.
- Susceptible infections · 5-10 mg/kg · PO · q24h · 2-3 days beyond the cessation of clinical signs (maximum 30 days) · Administer preferably on an empty stomach, unless GI upset occurs.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
給藥途徑
禁忌症
- 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)
不良反應
- 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)
藥物相互作用
- Antacids (Mg++, Al+++, Ca++) · May bind to difloxacin and prevent its absorption; separate doses by at least 2 hours.
- Dairy Products · Calcium content may decrease absorption; separate doses by at least 2 hours.
- Aminoglycosides, 3rd-gen Cephalosporins, Extended-spectrum Penicillins · Unpredictable synergism may occur against some bacteria, particularly Pseudomonas aeruginosa.
- Cyclosporine · May exacerbate nephrotoxicity and reduce the metabolism of systemic cyclosporine.
- Glyburide · Severe hypoglycemia is possible.
- Iron and Zinc supplements · Decreased difloxacin 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 · Difloxacin may alter phenytoin blood levels.
- Probenecid · May block tubular secretion and increase the blood level and half-life of difloxacin.
- Sucralfate · May inhibit absorption of difloxacin; separate doses by at least 2 hours.
- Theophylline · Difloxacin may increase theophylline blood levels, potentially leading to toxicity.
監測
- Clinical efficacy (resolution of infection)
- Gastrointestinal signs (appetite, vomiting, diarrhea)
- CNS signs (especially in patients with a history of seizures)
過量
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.
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。