頭孢唑林
頭孢唑林是一種主要透過注射給藥的**第一代頭孢菌素類**抗生素，在獸醫學中被廣泛使用。雖然它未獲 FDA 批准專門用於獸醫物種，但它是臨床上用於**外科手術預防性投藥**（特別是骨科與軟組織手術）以及治療全身性感染（包括敗血症）的主力藥物。 **臨床重點：** * **抗菌譜：** 對大多數革蘭氏陽性病原體（如中間型葡萄球菌、金黃色葡萄球菌、鏈球菌屬）具有極佳的覆蓋率，但對革蘭氏陰性病原體的覆蓋率則不穩定或較差。它對大多數厭氧菌非常有效，但脆弱擬桿菌（*Bacteroides fragilis*）除外。 * **藥效學：** 它是一種**時間依賴型**殺菌抗生素。其療效取決於在給藥間隔的大部分時間內，將感染部位的藥物濃度維持在最低抑菌濃度（MIC）以上。目前越來越多地採用恆速靜脈輸注（CRI）方案來優化此參數。 * **給藥方式：** 由於口服吸收不佳，必須透過腸胃外途徑（IV、IM、SC、IO）給藥。靜脈注射應在 3-5 分鐘內緩慢進行，以減少不良反應。
作用機制: Cefazolin is a **bactericidal beta-lactam antibiotic**. **Mechanism of Action:** * **Target:** Binds to specific **Penicillin-Binding Proteins (PBPs)** located inside the bacterial cell wall. * **Pathway:** Beta-lactam ring binds PBPs → Inhibition of the transpeptidation enzyme → Prevention of peptidoglycan cross-linking → Weakening of the bacterial cell wall. * **Result:** The defective cell wall makes the bacteria highly susceptible to osmotic pressure, leading to **cell lysis** and death. As a time-dependent antibiotic, its bacterial killing is maximized by optimizing the duration of time that free drug concentrations remain above the MIC (T > MIC).
各物種劑量
- Gram-positive infections · 10 mg/kg or 10-30 mg/kg · IV, IM · q8h · 10 mg/kg IV or IM q8h; OR 10-30 mg/kg IV q8h
- Gram-negative infections · 30 mg/kg or 10-30 mg/kg · IM, SC, IV · q8h · 30 mg/kg IM or SC; OR 10-30 mg/kg IV q8h
- Surgical prophylaxis (Orthopedic procedures) · 20 mg/kg at induction followed by 20 mg/kg every 90 minutes until wound closure · IV · q90m · Perioperative
- Surgical prophylaxis (Soft tissue surgery) · 20 mg/kg at time of surgery followed by a second dose of 20 mg/kg 6 hours later · IV/SC · Once then 6 hours later · Perioperative · First dose IV, second dose SC
- Sepsis · 20-25 mg/kg · IV · q4-8h
- Systemic infections · 33 mg/kg · IV, IM · q8-12h · As long as necessary
- Susceptible infections · 20-25 mg/kg · IM, IV · q8h
- Infections in neonates · 10-30 mg/kg · IV, IO · q8h
- Susceptible infections · 25 mg/kg · IV, IM · q6h
- Susceptible infections · 25 mg/kg · IV, IM · q6-8h
- Susceptible infections (Foals) · 20 mg/kg · IV · q8-12h
給藥途徑
禁忌症
- Patients with a known history of hypersensitivity to cephalosporins
不良反應
- Hypersensitivity reactions (rashes, fever, eosinophilia, anaphylaxis)
- Pain at the IM injection site
- Sterile abscesses or local tissue reactions (rare)
- Thrombophlebitis (following IV administration)
- Nephrotoxicity (minimal risk at clinical doses)
- Neurotoxicity or seizures (associated with very high IV doses)
- GI flora disruption (in nursing neonates)
藥物相互作用
- Aminoglycosides · Potential for additive nephrotoxicity; use concurrently with caution.
- Amphotericin B · Potential for additive nephrotoxicity; use concurrently with caution.
- Probenecid · Competitively blocks the renal tubular secretion of cefazolin, thereby increasing serum levels and prolonging the elimination half-life.
監測
- Clinical efficacy (resolution of clinical signs, normalization of WBC count, fever reduction)
- Renal function (BUN, creatinine, urinalysis) in patients with pre-existing renal impairment
- Signs of hypersensitivity or injection site reactions
過量
Cephalosporin overdoses are unlikely to cause significant problems. However, **very high doses given rapidly IV could potentially cause seizures** or neurotoxicity. Treatment for overdose 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。