モンテルカストナトリウム
**モンテルカストナトリウム**はロイコトリエン受容体拮抗薬です。獣医療では主に**猫**の以下の炎症性疾患に対する適応外使用として用いられます： * **猫喘息** * **炎症性腸疾患（IBD）** * 慢性上気道感染症 * **犬糸状虫随伴性呼吸器疾患（HARD）** > **臨床のポイント：** 炎症性メディエーターを阻害するため猫喘息に理論上は有効ですが、臨床的な有効性は期待外れであることが多く、通常は第一選択薬ではなく二次または三次の補助療法として考慮されます。再発性気道閉塞（RAO）の馬を対象とした小規模試験でも有効性は示されませんでした。ヒトではアレルギー性鼻炎および喘息の治療薬としてFDAに承認されています。
作用機序: Montelukast acts as a highly selective and competitive **cysteinyl leukotriene receptor (CysLT1) antagonist**. * Arachidonic acid → 5-lipoxygenase pathway → **Cysteinyl leukotrienes (LTC4, LTD4, LTE4)**. * These leukotrienes are potent inflammatory mediators released by **mast cells** and **eosinophils**. * By blocking the **CysLT1 receptor** in the airways and gastrointestinal tract, montelukast prevents leukotriene-mediated bronchoconstriction, mucosal edema, vascular permeability, and eosinophil recruitment.
動物種別の用量
- Feline asthma · 0.5-1 mg/kg PO once daily (q24h) · PO · q24h · Anecdotal reports of efficacy; more conclusive evidence is needed before regular use.
- Adjunctive treatment of the chronic 'snuffler' · 0.25-0.5 mg/kg PO q24h · PO · q24h · i.e., 1/8th of a 10 mg Singulair tablet.
- Inflammatory Bowel Disease (IBD) · 0.5-1 mg/kg PO once daily · PO · q24h · For mild cases involving eosinophils and lymphocytes. May be used in combination with other drugs.
- Adjunctive treatment of feline heartworm · 2 mg total dose (PO) once daily · PO · q24h · Anecdotal evidence suggests it may help thwart acute, fatal lung injury when an adult worm dies.
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 montelukast or any component of the product
- Not for use in reversing acute bronchospasm (asthma attacks)
有害事象
- No significant adverse effects reported in cats to date
- Humans (rare): behavioral effects (aggression, suicidal thoughts), palpitations, cholestatic hepatitis, allergic granulomatous angiitis
薬物相互作用
- Phenobarbital · CYP-450 enzyme inducer; may reduce montelukast plasma concentrations and efficacy.
- Rifampin · CYP-450 enzyme inducer; may reduce montelukast plasma concentrations and efficacy.
- Prednisone / Prednisolone · Severe peripheral edema has been reported in a human receiving both drugs, presumably due to increased renal tubular sodium and fluid retention. Clinical significance in veterinary patients is unclear.
モニタリング
- Clinical efficacy (improvement in respiratory or GI signs)
過量投与
**Overdose Toxicity:** Montelukast is relatively safe in overdose situations. * **Animal Data:** Rats and mice survived oral doses of approximately 230X to 335X the usual human adult dose. * **Human Data:** Doses as high as 1,000 mg have been reported with the majority having no adverse effects. * **Clinical Signs (if present):** Headache, vomiting, psychomotor hyperactivity, thirst, somnolence, mydriasis, hyperkinesia, and abdominal pain. * **Treatment:** Basically supportive. No specific antidote is known.
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。