ピペラシリンナトリウム
ピペラシリンは、主に重度または耐性菌による感染症に使用される**広域アシルアミノペニシリン**系抗生物質です。 * **広域スペクトル**: 多くの好気性および嫌気性のグラム陽性・陰性菌に対して拡張された抗菌力を持ち、特に**緑膿菌 (Pseudomonas aeruginosa)** や腸内細菌科の多くの株を含みます。 * **臨床用途**: 獣医療での経験は限られていますが、培養および感受性試験の結果が出るまでの重症患者に対する経験的治療、または混合感染やグラム陰性菌の汚染が懸念される外科的予防において非常に有用です。 * **β-ラクタマーゼ感受性**: 他のアミノペニシリンと同様に、ピペラシリン単独ではβ-ラクタマーゼ酵素によって分解されやすいです。この耐性を克服するため、しばしばβ-ラクタマーゼ阻害剤（タゾバクタムなど）と組み合わせて使用されます。 * **投与方法**: 経口ではほとんど吸収されないため、非経口（静脈内、筋肉内、または皮下）で投与する必要があります。
作用機序: Piperacillin is a **bactericidal** time-dependent antibiotic. * It binds to specific **Penicillin-Binding Proteins (PBPs)** (especially PBP-3) located inside the bacterial cell wall. * Binding to PBPs → inhibition of the third and final stage of bacterial cell wall synthesis (cross-linking of **peptidoglycan** strands). * This weakens the cell wall → activation of bacterial autolysins → **cell lysis and death**. * *Note*: Its efficacy is highly dependent on the amount of time the drug concentration remains above the Minimum Inhibitory Concentration (MIC) of the target pathogen.
動物種別の用量
- For bacteremia with or without endocarditis · 30 mg/kg IV q6h for 7-14 days · IV · q6h · 7-14 days
- For respiratory infections · 25-50 mg/kg IV q8h · IV · q8h
- For susceptible infections · 15-50 mg/kg IV or IM q6-12h · IV/IM · q6-12h
- For Bordetella avium infections · 150 mg/kg IM q8-12h · IM · q8-12h · minimum treatment period is two weeks
- For susceptible infections · 100 mg/kg IM two to three times daily · IM · BID-TID
- For empirical treatment in Psittacines of gram-negative bacterial infections · 100 mg/kg IM 3-4 times a day if immunocompetent; 4 times a day if immunocompromised · IM · TID-QID
- For bacteremia with or without endocarditis · 30 mg/kg IV q6h for 7-14 days · IV · q6h · 7-14 days
- For respiratory infections · 25-50 mg/kg IV q8h · IV · q8h
- For systemic treatment of otitis media or proliferative otitis externa complicated by gram-negative (especially Pseudomonas) bacteria · 20 mg/kg SC three times daily · SC · TID
投与経路
禁忌
- Patients with documented hypersensitivity to beta-lactam antibiotics (penicillins, cephalosporins)
有害事象
- Hypersensitivity reactions (allergic reactions)
- Local tissue irritation, pain at IM injection site
- Thrombophlebitis (with IV administration)
- Antibiotic-associated diarrhea (due to alterations in gut flora)
- Coagulation abnormalities (rare, mostly in renal failure)
- Neurotoxicity/seizures (at very high doses or in renal impairment)
- Clostridium difficile superinfections (rare)
薬物相互作用
- Aminoglycosides (amikacin, gentamicin, tobramycin) · Synergistic against certain bacteria in vitro, but penicillins can chemically inactivate aminoglycosides in vivo (especially in renal failure or at massive doses). Do not mix in the same syringe/bag.
- Anticoagulants (heparin, warfarin) · Piperacillin may rarely affect platelets; increased monitoring of coagulation parameters is suggested.
- Methotrexate · Piperacillin may increase methotrexate serum levels.
- Probenecid · Reduces renal tubular secretion of piperacillin, maintaining higher systemic levels for longer periods.
- Vecuronium · Piperacillin may prolong neuromuscular blockade.
モニタリング
- Clinical efficacy (resolution of clinical signs, fever)
- White blood cell count (WBC)
- Renal function (if prolonged use or pre-existing impairment)
- Coagulation parameters (if on concurrent anticoagulants or high doses)
過量投与
Single overdoses are unlikely to pose much risk. * **Massive Overdoses**: May cause vomiting, diarrhea, or neurotoxicity (seizures). * **Chronic High Doses**: Dogs receiving up to 800 mg/kg/day of piperacillin/tazobactam for 6 months demonstrated no serious toxic effects. Doses ≥400 mg/kg/day caused transient liver effects (glycogen granules in cytoplasm, increased smooth endoplasmic reticulum) that mostly reversed after one month. * **Treatment**: Supportive care. Monitor renal and neurological status.
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。