シプロフロキサシン
**シプロフロキサシン**は、第2世代の**フルオロキノロン系抗菌薬**であり、人医療で広く使用され、獣医療でも適応外使用として頻繁に利用されます。 * **抗菌スペクトル**: 広域スペクトルを持ち、多くのグラム陰性桿菌および球菌（緑膿菌、大腸菌、クレブシエラ属など）や一部のグラム陽性菌（メチシリン耐性株を含むブドウ球菌属など）に対して高い有効性を示します。嫌気性菌やほとんどのレンサ球菌に対する活性は弱いです。 * **薬物動態学的特徴**: 犬における経口バイオアベイラビリティはエンロフロキサシンよりも著しく低く不安定です（エンロフロキサシンが80%以上であるのに対し、約40〜50%）。そのため、犬においてエンロフロキサシンの1:1の経口代替薬とは通常みなされません。 * **臨床的有用性**: 真の静脈内（IV）フルオロキノロン製剤が必要な場合、特定の培養結果に基づく治療、またはより大きな経口剤形が望まれる場合によく選択されます。
作用機序: Ciprofloxacin is a **bactericidal**, **concentration-dependent** antibiotic. * It enters the bacterial cell and inhibits two key type-II topoisomerase enzymes: **DNA gyrase** (primary target in gram-negative bacteria) and **Topoisomerase IV** (primary target in gram-positive bacteria). * Inhibition of these enzymes → prevents DNA supercoiling and relaxation → halts DNA replication and transcription → rapid bacterial cell death (within 20-30 minutes of exposure). * Exhibits a significant **post-antibiotic effect (PAE)**, meaning bacterial growth continues to be suppressed even after drug concentrations fall below the minimum inhibitory concentration (MIC).
動物種別の用量
- Susceptible infections · 5-15 mg/kg PO q12h · PO · q12h · Avoid or reduce dosage in severe renal failure; avoid in young animals or pregnant/breeding animals.
- Ocular infections · 1 drop to affected eye · topical · q6h · Not specified · Standard therapy
- Severe ocular infections (intensive therapy) · 1 drop to affected eye · topical · q30-120mins · 1-2 days · For short-term intensive use
- Susceptible infections · 5-15 mg/kg PO twice daily · PO · twice daily
- Susceptible gram-negative infections · 20-40 mg/kg PO twice daily · PO · twice daily · Using ciprofloxacin 500 mg tablets. Crushed tablet goes into suspension well, but must be shaken well before administering.
- Susceptible gram-negative infections · 20 mg/kg PO q12h · PO · q12h · Using crushed tablets
- Susceptible gram-negative infections · 10-15 mg/kg PO q12h · PO · q12h · Using crushed tablets or suspend
- Susceptible infections (Ratites) · 3-6 mg/kg PO twice daily · PO · twice daily
- Susceptible infections (Rabbits) · 5-20 mg/kg PO q12h · PO · q12h
投与経路
禁忌
- Hypersensitivity to fluoroquinolones
- Small and medium breed dogs 2-8 months of age (due to cartilage damage)
- Large and giant breed dogs during their rapid growth phase (past 8 months of age)
- Known hypersensitivity to ciprofloxacin or other fluoroquinolones
有害事象
- GI distress (vomiting, anorexia)
- Cartilage abnormalities in young, growing animals
- CNS stimulation (dizziness, seizures)
- Crystalluria
- Hypersensitivity reactions
- Local irritation after application
- Local burning and itching (reported in humans)
- Lid margin crusting (reported in humans)
- Hyperaemia (reported in humans)
- Taste disturbances (reported in humans)
- Corneal staining (reported in humans)
- Keratitis (reported in humans)
- Lid oedema (reported in humans)
- Lacrimation (reported in humans)
- Photophobia (reported in humans)
- Corneal infiltrates (reported in humans)
薬物相互作用
- Antacids/Dairy Products (Mg++, Al+++, Ca++) · May bind to ciprofloxacin and prevent its absorption; separate doses by at least 2 hours
- Antibiotics (aminoglycosides, 3rd-generation cephalosporins, extended-spectrum penicillins) · Synergism may occur against some bacteria (particularly Pseudomonas aeruginosa)
- Cyclosporine · May exacerbate nephrotoxicity and reduce the metabolism of cyclosporine
- Glyburide · Severe hypoglycemia possible
- Iron, Zinc (oral) · Decreased ciprofloxacin absorption; separate doses by at least two hours
- Methotrexate · Increased MTX levels possible with resultant toxicity
- Nitrofurantoin · May antagonize the antimicrobial activity of fluoroquinolones; concomitant use not recommended
- Phenytoin · May alter phenytoin levels
- Probenecid · Blocks tubular secretion of ciprofloxacin and may increase its blood level and half-life
- Quinidine · Increased risk for cardiotoxicity
- Sucralfate · May inhibit absorption of ciprofloxacin; separate doses by at least 2 hours
- Theophylline · May increase theophylline blood levels
モニタリング
- Clinical efficacy
- Adverse effects (GI signs, CNS stimulation)
- Hydration status
- Clinical resolution of ocular infection
- Corneal healing (via fluorescein staining)
- Signs of local irritation or hypersensitivity
過量投与
Little specific information is available for ciprofloxacin overdosage in veterinary species. Overdoses may result in GI distress, CNS signs (tremors, seizures), or renal toxicity (crystalluria). Treatment should consist of supportive care, maintaining adequate hydration to prevent crystalluria, and gastric decontamination if ingestion was recent. See the enrofloxacin monograph for more extrapolated information.
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。