頭孢他啶
頭孢他啶 (Ceftazidime) 是一種強效的**第三代頭孢菌素類注射用抗生素**，主要用於治療對其他藥物具抗藥性的嚴重**革蘭氏陰性菌**感染（特別是綠膿桿菌 *Pseudomonas aeruginosa*）。由於其在爬蟲類體內的半衰期極長，在特寵獸醫學中特別受歡迎，允許較長的給藥間隔（例如每三天一次）。通常以靜脈、肌肉或皮下注射給藥。
作用機制: Ceftazidime is a **bactericidal** time-dependent antibiotic. It binds to specific **penicillin-binding proteins (PBPs)** located inside the bacterial cell wall → inhibits the third and final stage of bacterial cell wall synthesis (peptidoglycan cross-linking) → weakens the cell wall → leads to cell lysis and death due to osmotic instability. *Note: While it retains some gram-positive activity from earlier generations, its primary strength is its expanded gram-negative spectrum, including antipseudomonal activity.*
各物種劑量
- Initial antibiotic therapy of gram-negative infections · 25 mg/kg · IM or SC · q8-12h
- Initial treatment of orthopedic infections · 25 mg/kg · IV, IM · q8-12h
- Initial treatment of soft tissue infections · 30-50 mg/kg · IV, IM · q8-12h
- Initial treatment of sepsis, bacteremia · 15-30 mg/kg · IV, IM · q6-8h
- Susceptible infections · 30 mg/kg · IV/IM/SC · q8h · Empirical dose; maintain tissue concentrations above MIC.
- Pseudomonas aeruginosa infections · 30 mg/kg · IV/IM/SC · q4h · Increased frequency required for Pseudomonas.
- Pseudomonas aeruginosa infections (CRI) · 4.4 mg/kg loading dose followed by 4.1 mg/kg/h · IV · CRI · Continuous rate infusion to maintain time > MIC.
- Initial treatment of systemic infections · 25-30 mg/kg · IV, IM or intraosseous · q8-12h
- Susceptible infections · 30 mg/kg · IM · q8h · Empirical dose.
- Pseudomonas infections · 30 mg/kg · IM · q2-4h · More frequent dosing recommended for Pseudomonas.
- Susceptible infections · 20 mg/kg · IM or SC · q72hours (every 3 days)
- Bacterial infections in snakes (particularly Enterobacteriaceae or Pseudomonas aeruginosa) · 20 mg/kg · IM · q72h · Maintain at 30°C
- Chelonians · 50 mg/kg · IM · q24h
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
- Known hypersensitivity or prior allergic reaction to cephalosporins
不良反應
- Pain at IM injection site (SC may be less painful)
- Gastrointestinal effects (diarrhea, vomiting)
- Hypersensitivity reactions (allergic reactions)
- Granulocytopenia
- Thrombocytopenia
- Mild azotemia
- Pseudomembranous colitis (C. difficile)
- Increased serum liver enzymes (reported in humans)
藥物相互作用
- Aminoglycosides / Nephrotoxic drugs (e.g., amphotericin B) · Potential additive nephrotoxicity. In vitro synergy exists against certain bacteria, but they must NOT be mixed in the same syringe or fluid bag (administer separately).
- Chloramphenicol · May be antagonistic to ceftazidime's bactericidal effects on gram-negative bacilli; concurrent use is not recommended.
- Oxytetracycline · Bacteriostatic agents may antagonize the bactericidal activity of ceftazidime. · moderate
- Erythromycin · Bacteriostatic agents may antagonize the bactericidal activity of ceftazidime. · moderate
- Amphotericin B · Increased risk of nephrotoxicity when used concurrently. · major
- Furosemide · Loop diuretics may increase the risk of nephrotoxicity. · moderate
- Aminoglycosides · Synergistic in vivo against Pseudomonas; however, chemically incompatible in vitro (do not mix in the same syringe). · major
監測
- Clinical efficacy (resolution of infection signs)
- Baseline and ongoing renal function (BUN, Creatinine, Urinalysis)
- Injection site for signs of pain or inflammation
過量
An acute overdose in patients with normal renal function is unlikely to be of great concern. However, in patients with **renal failure**, overdosage of ceftazidime has caused seizures, encephalopathy, coma, neuromuscular excitability, asterixis, and myoclonia. **Treatment:** Primarily symptomatic and supportive. Hemodialysis could be used to enhance elimination.
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。