セフォキシチン
セフォキシチンは、獣医療において重度または混合性の細菌感染症の治療に使用される**第2世代の注射用セファロスポリン**（厳密にはセファマイシンに分類されます）です。 主な薬理学的特徴は以下の通りです： * **嫌気性菌への有効性**：他の多くの初期世代セファロスポリンとは異なり、セフォキシチンはバクテロイデス・フラジリス（*Bacteroides fragilis*）を含む**嫌気性菌**に対して非常に有効です。 * **グラム陰性菌スペクトル**：第1世代薬に耐性を示す可能性のある大腸菌（*E. coli*）、クレブシエラ（*Klebsiella*）、プロテウス（*Proteus*）の多くの株に対して良好な活性を示します。 * **グラム陽性菌スペクトル**：グラム陽性球菌に対する活性も維持していますが、重量あたりの効力は第1世代セファロスポリンに比べてわずかに劣ります。 > **臨床のポイント**：強力な嫌気性菌スペクトルを持つため、セフォキシチンは誤嚥性肺炎、腸管穿孔、重度の軟部組織感染症や敗血症などの混合感染症に頻繁に選択されます。
作用機序: Cefoxitin is a **bactericidal** antibiotic that works by inhibiting bacterial cell wall synthesis. * It covalently binds to specific **Penicillin-Binding Proteins (PBPs)** located inside the bacterial cell wall. * Binding to PBPs → **inhibits the transpeptidation enzyme** responsible for cross-linking peptidoglycan strands. * Lack of cross-linking → weakens the bacterial cell wall → leads to osmotic instability, cell lysis, and bacterial death. * As a cephamycin, cefoxitin is highly resistant to degradation by many **beta-lactamases**, particularly those produced by *Bacteroides* species.
動物種別の用量
- Systemic infections · 25-30 mg/kg IV or IM q8h · IV/IM · q8h · Use as long as necessary to control initial infection, then switch to oral drugs
- Sepsis · 30 mg/kg IV q5h · IV · q5h
- Susceptible infections · 30 mg/kg IV q8h · IV · q8h
- Non-tuberculosis mycobacteria (NTM) - second line treatment · 30-40 mg/kg IV, IM or SC q6-8h · IV/IM/SC · q6-8h · Causes pain on injection with IM or SC
- Susceptible infections (Foals) · 20 mg/kg IV q4-6h · IV · q4-6h
- Mixed infections (e.g., aspiration pneumonia, bowel perforation) · 30 mg/kg SC q8h; 30 mg/kg IV q4-6h · SC/IV · q8h or q4-6h
- Sepsis · 30 mg/kg IV q5h · IV · q5h
- Soft tissue infections · 30 mg/kg SC q8h or 30 mg/kg IV q5h · SC/IV · q8h or q5h
- Bacteremia · 15-30 mg/kg IV, IM SC q6-8h · IV/IM/SC · q6-8h
- Orthopedic infections · 22 mg/kg IV, IM q6-8h · IV/IM · q6-8h · Use as long as necessary to control initial infection, then switch to oral drugs
投与経路
禁忌
- Patients with a history of hypersensitivity to cephalosporins
- Use with extreme caution in patients documented to be hypersensitive to other beta-lactams (penicillins, carbapenems)
有害事象
- Hypersensitivity reactions (rashes, fever, eosinophilia, lymphadenopathy, anaphylaxis)
- Pain at the injection site (IM)
- Sterile abscesses or local tissue reactions
- Thrombophlebitis (IV administration)
- Antibiotic-associated diarrhea or altered gut flora
- Superinfections
- Nephrotoxicity (rare at clinical doses)
- Neurotoxicity, neutropenia, thrombocytopenia, hepatitis (associated with high doses or prolonged use)
薬物相互作用
- Aminoglycosides / Nephrotoxic Drugs · Potential for additive nephrotoxicity. While in vitro synergy exists against certain bacteria, they should not be mixed in the same syringe or fluid bag.
- Probenecid · Competitively blocks the tubular secretion of cefoxitin, thereby increasing serum levels and prolonging elimination half-lives.
モニタリング
- Clinical efficacy (resolution of infection signs)
- Renal function (BUN, creatinine, urinalysis) in patients with diminished renal capacity
過量投与
Acute oral cephalosporin overdoses are unlikely to cause significant problems other than **gastrointestinal distress**. Massive parenteral overdoses or prolonged accumulation (especially in renal failure) may lead to: * Neurotoxicity (seizures) * Neutropenia or thrombocytopenia * Hepatitis * Nephrotoxicity (tubular necrosis) Treatment is supportive and symptomatic.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。