ネオマイシン
**ネオマイシン**は、主にグラム陰性好気性菌に対して有効な広域スペクトルの殺菌性**アミノグリコシド系抗生物質**です。 全身投与時の腎毒性が他のアミノグリコシド系(ゲンタマイシンやアミカシンなど)よりも著しく高いため、獣医学での使用は主に以下に制限されています: * **局所投与**(皮膚、眼、耳) * 腸管感染症や手術前の「腸管滅菌」のための**経口投与** * **肝性脳症**の管理(結腸内のアンモニア産生菌を減少させるため) > **臨床のポイント:** 全てのアミノグリコシド系と同様に、ネオマイシンは**濃度依存性の殺菌作用**と有意なポストアンチバイオティックエフェクト(PAE)を示します。しかし、無傷の消化管からの吸収は非常に悪く(わずか約3%)、全身毒性を最小限に抑えながら腸管内で局所的に作用するのに理想的です。
作用機序: Neomycin actively transports across the bacterial cell membrane (an **oxygen-dependent** process, hence its lack of efficacy against anaerobes). It irreversibly binds to the **30S ribosomal subunit** → causes misreading of mRNA → inhibits protein synthesis → leads to rapid bacterial cell death.
動物種別の用量
- Hepatic encephalopathy · 22 mg/kg q8h PO · PO · q8h
- Hepatic encephalopathy · 20 mg/kg PO q8-12h · PO · q8-12h · Used with or without lactulose.
- Hepatic encephalopathy (stable animals) · 20 mg/kg PO q12h · PO · q12h · Avoid if evidence of intestinal bleeding, ulcerations, or renal failure.
- Campylobacteriosis · 20 mg/kg PO q12h · PO · q12h
- Systemic therapy · 3.5 mg/kg IV , IM or SC q8h · IV/IM/SC · q8h · Caution: Very nephrotoxic.
- Susceptible enteral infections (Young pigs) · 0.75-1 grams/day, PO divided 2-4 times daily at regular intervals · PO · divided 2-4 times daily · Doses are not standardized; use for general guidance only.
- Susceptible enteral infections · 7-12 mg/kg, PO q12h · PO · q12h
- Susceptible enteric infections · 10-20 mg/kg, PO twice to four times daily · PO · q6-12h
- Susceptible enteral infections (Lambs) · 0.75-1 grams/day PO divided 2-4 times daily at regular intervals · PO · divided 2-4 times daily · Doses are not standardized; use for general guidance only.
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Hypersensitivity to aminoglycosides
- Intestinal obstruction (for oral use)
- Rabbits and hares (disrupts GI flora)
- Neonates (avoid oral use due to higher systemic absorption)
- Animals with a perforated tympanic membrane (eardrum)
- Concurrent use with other known ototoxic products
- Known hypersensitivity to aminoglycosides
- Pre-existing renal disease (for systemic use)
- Ruptured tympanic membrane (for otic preparations)
有害事象
- Nephrotoxicity (severe if given parenterally)
- Ototoxicity (irreversible, parenteral or rarely oral)
- Severe diarrhea
- Intestinal malabsorption
- GI superinfections (with chronic oral use)
- Ototoxicity (deafness)
- Vestibular toxicity (ataxia, head tilt, nystagmus)
- Local irritation or erythema at the application site
- Ototoxicity (vestibular and auditory)
- Nephrotoxicity
- Severe diarrhoea or malabsorption syndrome (oral use)
- Bacterial or fungal superinfections
- Local irritation (topical ophthalmic use)
薬物相互作用
- Digoxin · Oral neomycin may decrease digoxin absorption. In a small subset of patients who metabolize digoxin in the GI tract, neomycin may increase serum digoxin levels. · moderate
- Methotrexate · Absorption may be reduced by oral neomycin. · moderate
- Ototoxic or Nephrotoxic Drugs · Concurrent use increases the risk of additive toxicity, even with oral neomycin, and should be done with caution.
- Penicillin VK (oral) · Concurrent use may cause malabsorption of the penicillin.
- Warfarin · Oral neomycin may decrease vitamin K absorption from the gut, potentially increasing anticoagulant effects.
- Other ototoxic drugs (e.g., loop diuretics, other aminoglycosides) · Increased risk of cumulative ototoxicity (deafness and vestibular dysfunction) · major
- Potassium · Decreased absorption of potassium · minor
- Vitamin K · Decreased absorption of vitamin K · moderate
- Furosemide · Synergistic ototoxicity and nephrotoxicity · major
モニタリング
- Clinical efficacy
- Systemic and GI adverse effects with prolonged use
- Renal function parameters (BUN, creatinine, urinalysis) if used parenterally
- Resolution of clinical signs of otitis
- Integrity of the tympanic membrane (via otoscopy)
- Hearing function and vestibular signs (head tilt, ataxia, nystagmus)
- Renal function (BUN, Creatinine, Urinalysis for casts/protein)
- Hearing and vestibular function (head tilt, nystagmus, ataxia)
- Gastrointestinal signs (diarrhoea)
過量投与
Parenteral overdosage carries a high risk of severe **nephrotoxicity** and **ototoxicity**. Oral overdosage is less likely to cause systemic toxicity unless the gut wall is compromised, but can lead to severe diarrhea and malabsorption.
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。