セフチオフル塩酸塩
セフチオフル塩酸塩は、**獣医専用の第3世代セファロスポリン系**抗生物質です。主に大動物（特に豚や牛）の細菌性呼吸器疾患、趾間腐爛（フットロット）、急性子宮内膜炎、乳房炎の治療に使用されます。 主な特徴： * **広域スペクトル：** *パスツレラ*、*レンサ球菌*、*ブドウ球菌*、*サルモネラ*、*大腸菌*など、多様なグラム陽性および陰性菌に対して有効です。 * **活性代謝物：** 投与後速やかにデスフロイルセフチオフルに変換され、親化合物と同等の効力を示します。 * **臨床上のポイント：** 一部の製剤（Excenel RTUなど）は、泌乳牛において休薬期間（廃棄乳期間）がゼロであるため、酪農業において非常に有用ですが、屠畜に関する休薬期間は厳守する必要があります。
作用機序: Ceftiofur is a **time-dependent, bactericidal** antibiotic. * **Mechanism:** It binds to **penicillin-binding proteins (PBPs)** located inside the bacterial cell wall → inhibits the third and final stage of bacterial cell wall synthesis → leads to weakened cell walls, cell lysis, and bacterial death. * **Metabolism Pathway:** Parent ceftiofur is rapidly cleaved into furoic acid and **desfuroylceftiofur** (the primary active metabolite). * **Reservoir Effect:** The active metabolite is highly protein-bound, which creates a 'reservoir effect' that maintains active, therapeutic drug concentrations at the site of infection for extended periods.
動物種別の用量
- Susceptible urinary tract infections · 2.2 mg/kg · SC · q24h · Not specified · Authorized for use in dogs in other countries where the main indication is UTI treatment.
- Sepsis/bacteraemia · 4.4 mg/kg · SC · q24h · Not specified · Higher (double) dose indicated to treat sepsis/bacteraemia.
- Bovine respiratory disease and acute bovine interdigital necrobacillosis · 1.1 to 2.2 mg/kg · IM/SC · q24h · 3 days (up to 5 days if needed) · Do not inject more than 15 mL per injection site.
- Bovine respiratory disease (BRD) only · 2.2 mg/kg · IM/SC · q48h · Days 1 and 3 · Do not inject more than 15 mL per injection site.
- Acute post-partum metritis · 2.2 mg/kg · IM/SC · q24h · 5 consecutive days · Do not inject more than 15 mL per injection site.
- Neonatal salmonellosis · 5 mg/kg · IM · q24h · 5 days
- Subclinical mastitis at time of dry off · Infuse one syringe (500 mg) · Intramammary · Once · At dry off · Infuse into each affected quarter.
- Clinical mastitis in lactating dairy cattle · Infuse one syringe (125 mg) · Intramammary · q24h · 2 days (up to 8 consecutive days for extended therapy) · Infuse into each affected quarter.
- Bacterial respiratory disease · 3 to 5 mg/kg · IM · q24h · 3 consecutive days · 1 mL of sterile suspension per 22 to 37 lb body weight.
投与経路
禁忌
- Patients with a documented history of hypersensitivity to cephalosporins
- Use with caution in patients hypersensitive to other beta-lactam antibiotics (e.g., penicillins, carbapenems) due to potential cross-reactivity
有害事象
- Pain on IM injection (especially in small animals)
- Hypersensitivity reactions (rashes, fever, eosinophilia, lymphadenopathy, anaphylaxis)
- Gastrointestinal distress / diarrhea
- Granulocytopenia (rare)
- Thrombocytopenia (rare)
- Injection site discoloration
薬物相互作用
- Aminoglycosides / Nephrotoxic Drugs (e.g., amphotericin B) · Potential for additive nephrotoxicity. In vitro studies show synergistic antibacterial activity, but they must NOT be mixed together in the same syringe or fluid line.
- Probenecid · Competitively blocks the tubular secretion of most cephalosporins, thereby increasing serum levels and prolonging serum half-lives.
- Aminoglycosides · Synergistic antibacterial effect, but should not be mixed in the same syringe due to chemical incompatibility. · moderate
- Amphotericin B · Increased risk of nephrotoxicity. · major
- Loop diuretics (e.g., furosemide) · Increased risk of nephrotoxicity. · major
モニタリング
- Clinical efficacy and resolution of infection
- Weekly CBC monitoring (if used off-label in small animals)
- Renal function parameters in patients with pre-existing renal impairment
- Injection site reactions
過量投与
Cephalosporin overdoses are generally well-tolerated and unlikely to cause significant problems other than gastrointestinal distress. However, extreme overdoses could theoretically induce hypersensitivity or hematologic abnormalities. > **Important:** Use of dosages in excess of those labeled or via unapproved routes may cause violative tissue or milk residues. Contact FARAD for assistance in determining appropriate withdrawal times if an overdose occurs in food-producing animals.
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。