マルボフロキサシン
**マルボフロキサシン**は、主に獣医療で使用される合成の広域スペクトル**フルオロキノロン系抗菌薬**です。グラム陰性菌およびグラム陽性菌の両方に対して**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。細菌増殖の静止期および対数増殖期の両方で活性を示します。 * **抗菌スペクトル**：広範囲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、エンテロバクター、プロテウス、サルモネラなど）や、一部のグラム陽性菌（ペニシリナーゼ産生株を含むブドウ球菌など）に対して高い有効性を示します。 * **臨床上のポイント**：他のフルオロキノロン系と同様に、ほとんどの嫌気性菌に対する活性は弱く、レンサ球菌に対する有効性は不安定または不良です。嫌気性菌やレンサ球菌の感染症には推奨されません。 * **耐性**：主に染色体突然変異（特に緑膿菌、クレブシエラ、腸球菌）によって生じます。プラスミド介在性の耐性はまれです。
作用機序: Marbofloxacin exerts its bactericidal effect by targeting key bacterial enzymes involved in DNA replication and transcription: * Inhibits **DNA-gyrase** (topoisomerase II) → prevents DNA supercoiling. * Inhibits **Topoisomerase IV** → prevents separation of interlinked daughter DNA molecules. * **Result**: Disruption of DNA replication, transcription, and repair → rapid bacterial cell death (typically within 20-30 minutes of exposure).
動物種別の用量
- For susceptible infections (urinary tract, skin and soft tissue) · 2.75-5.5 mg/kg PO once daily · PO · q24h · Give for 2-3 days beyond cessation of clinical signs (skin/soft tissue); at least 10 days (urinary tract). Max 30 days. · If no improvement noted after 5 days, reevaluate diagnosis.
- First-line treatment for feline tuberculosis or non-tuberculous mycobacteria (NTM) · 2 mg/kg PO once daily · PO · q24h · Pending definitive diagnosis. Not effective against MAC infection.
- For hemoplasmosis · 2.75 mg/kg PO once daily (q24h) · PO · q24h
- Susceptible bacterial infections · 2 mg/kg · IV/SC/PO · q24h · Not specified · Do not use 20 mg or 80 mg tablets. May allow clearance of Mycoplasma haemofelis in persistently infected cats.
- Susceptible infections · 10 mg/kg PO at least every 48 hours · PO · q48h · Study done in Ball pythons (Python regius). Further studies required to determine effective doses and toxicity.
- For susceptible infections (urinary tract, skin and soft tissue) · 2.75-5.5 mg/kg PO once daily · PO · q24h · Give for 2-3 days beyond cessation of clinical signs (skin/soft tissue); at least 10 days (urinary tract). Max 30 days. · If no improvement noted after 5 days, reevaluate diagnosis.
- For susceptible Pseudomonas otitis · 5.5 mg/kg PO once daily · PO · q24h · Dose at the high end of the flexible dosing label for severe/chronic cases or when topical therapy is not possible.
投与経路
禁忌
- Hypersensitivity to fluoroquinolones
- Small and medium breed dogs up to 8 months of age
- Large breed dogs up to 12 months of age
- Giant breed dogs up to 18 months of age
- Cats under 12 months of age
- Food-producing animals (FDA prohibited)
- Cats (do not use 20 mg and 80 mg tablets)
- Dogs < 12 months of age
- Giant-breed dogs < 18 months of age
- Cats < 16 weeks of age
有害事象
- Gastrointestinal distress (vomiting, anorexia, soft stools, diarrhea)
- Decreased activity/lethargy
- Cartilage abnormalities in young, growing animals
- Elevated hepatic enzymes (rare)
- Ataxia, seizures, depression, nervousness (rare)
- Hypersensitivity reactions (rare)
- Crystalluria (rare)
- Potential ocular toxicity/blindness in cats (rare/unproven, but reported)
- Gastrointestinal signs (nausea, vomiting)
- Potential CNS toxicity (seizures)
- Cartilage abnormalities in growing animals
- Potential retinal toxicity/blindness in cats (at high doses)
薬物相互作用
- Antacids / Dairy Products · Cations (Mg++, Al+++, Ca++) may bind to marbofloxacin and prevent its absorption; separate doses by at least 2 hours
- Antibiotics (aminoglycosides, 3rd-gen cephalosporins, extended-spectrum penicillins) · Unpredictable synergism may occur against some bacteria, particularly Pseudomonas aeruginosa
- Cyclosporine · May exacerbate nephrotoxicity and reduce the metabolism of systemically used cyclosporine
- Flunixin · May increase AUC and elimination half-life of the fluoroquinolone, and vice versa (extrapolated from enrofloxacin)
- Glyburide · Severe hypoglycemia possible
- Iron, Zinc (oral) · Decreased marbofloxacin 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 · Marbofloxacin may alter phenytoin levels
- Probenecid · Blocks tubular secretion and may increase blood level and half-life of marbofloxacin
- Quinidine · Increased risk for cardiotoxicity
- Sucralfate · May inhibit absorption of marbofloxacin; separate doses by at least 2 hours · major
モニタリング
- Clinical efficacy (resolution of infection)
- Adverse effects (GI distress, CNS signs)
- Joint health/lameness in younger animals (if inadvertently used)
- Clinical efficacy and resolution of infection
- Culture and susceptibility results
- Signs of gastrointestinal upset
- Neurological signs (especially in patients with a history of seizures)
- Vision changes or mydriasis in cats
過量投与
Acute overdoses of marbofloxacin are unlikely to result in signs more serious than **anorexia or vomiting**, though other adverse effects (like CNS stimulation) could theoretically occur. * **Chronic Toxicity**: In safety studies, dogs receiving massive overdoses (55 mg/kg per day for 12 days) developed anorexia, vomiting, dehydration, tremors, red skin, facial swelling, lethargy, and weight loss. * **Treatment**: Management of overdose consists of drug withdrawal and symptomatic/supportive care. If ingestion was recent, gastrointestinal decontamination (emesis or activated charcoal) may be considered.
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