Montelukast Sodium
**Montelukast sodium** is a leukotriene receptor antagonist. In veterinary medicine, it is primarily used off-label in **cats** for inflammatory conditions such as: * **Feline asthma** * **Inflammatory bowel disease (IBD)** * Chronic upper respiratory infections ("snufflers") * **Heartworm-associated respiratory disease (HARD)** syndrome > **Clinical Pearl:** While theoretically promising for feline asthma by blocking inflammatory mediators, clinical efficacy has been largely disappointing. It is generally considered a second- or third-line adjunctive therapy rather than a primary treatment. A small trial in horses with Recurrent Airway Obstruction (RAO) also failed to show efficacy. In humans, it is FDA-approved for allergic rhinitis and asthma.
Mecanismo: 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.
Dosificación por especie
- 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.
Las dosis son una referencia clínica para médicos veterinarios. Confirme siempre con la información vigente del producto y el paciente individual.
Vías de administración
Contraindicaciones
- Hypersensitivity to montelukast or any component of the product
- Not for use in reversing acute bronchospasm (asthma attacks)
Efectos adversos
- No significant adverse effects reported in cats to date
- Humans (rare): behavioral effects (aggression, suicidal thoughts), palpitations, cholestatic hepatitis, allergic granulomatous angiitis
Interacciones farmacológicas
- 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.
Monitoreo
- Clinical efficacy (improvement in respiratory or GI signs)
Sobredosis
**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.
La referencia de fármacos de VetSheet está destinada a médicos veterinarios como apoyo a la decisión clínica; no sustituye el juicio profesional ni la información vigente del fabricante.