Montelukast for Allergies with Elevated Eosinophils
Montelukast can help with allergic conditions when eosinophils are elevated, but it is not the preferred first-line therapy for most allergic conditions and has limited efficacy in reducing eosinophilia compared to inhaled corticosteroids.
Role of Montelukast in Allergic Conditions
Montelukast is a leukotriene receptor antagonist (LTRA) that works by blocking cysteinyl leukotriene receptors, which are involved in allergic inflammation. Its effects on eosinophils and allergic conditions include:
- Montelukast inhibits bronchoconstriction due to inhaled LTD4 in asthmatics 1
- It can decrease peripheral blood eosinophil counts by 9-15% in asthma patients compared to placebo 1
- In patients with seasonal allergic rhinitis, montelukast shows a 12.3% difference in peripheral blood eosinophil counts compared to placebo 1
- It can decrease sputum eosinophils from 7.5% to 3.9% in some asthma patients 2
Effectiveness by Condition
For Asthma:
- Montelukast is considered an alternative, but not preferred therapy for mild persistent asthma (step 2 care) 3
- It is less effective than inhaled corticosteroids (ICS) as first-line therapy for asthma control 4
- Can be used as adjunctive therapy with ICS, but for adults and adolescents ≥12 years, it is not the preferred adjunctive therapy compared to long-acting beta-agonists (LABAs) 3
For Allergic Rhinitis:
- Montelukast has demonstrated efficacy similar to loratadine (antihistamine) but less than intranasal corticosteroids 5
- Combination with antihistamines may provide better results than either agent alone 5
For Eosinophilic Esophagitis (EoE):
- Not recommended for clinical use in EoE outside of clinical trials 3
- One RCT with adult participants (n=41) showed no difference in symptoms when used as maintenance therapy after histologic remission 3
Limitations in High Eosinophilia States
- Adding montelukast to existing high-dose corticosteroid therapy in subjects with elevated sputum eosinophils does not provide additional reduction of airway eosinophilia 6
- In eosinophilic esophagitis, montelukast has shown limited efficacy and is only recommended in the context of clinical trials 3
Mechanism of Action
Montelukast works by:
- Inhibiting cysteinyl leukotriene type-1 (CysLT1) receptors found in the human airway 1
- Blocking leukotriene-mediated effects including airway edema and smooth muscle contraction 1
- Potentially inhibiting IL-5 mRNA expression and reducing CysLT secretion by peripheral blood mononuclear cells from asthmatic patients 7
Practical Recommendations
For patients with allergies and elevated eosinophils:
For asthma: Consider montelukast as an alternative to ICS for mild persistent asthma if patients are unable or unwilling to use ICS 4
For allergic rhinitis: Montelukast can be effective, particularly when combined with antihistamines 5
For exercise-induced bronchoconstriction: Montelukast provides protection without developing tolerance 4
For patients with both asthma and allergic rhinitis: Montelukast may be particularly beneficial as it treats both conditions 5
Cautions and Monitoring
- Monitor for neuropsychiatric events including agitation, depression, and suicidal thinking 1
- Be alert for eosinophilia, vasculitic rash, worsening pulmonary symptoms, cardiac complications, and/or neuropathy 1
- In rare cases, patients with asthma on montelukast may present with systemic eosinophilia, sometimes with features of Churg-Strauss syndrome 1
In conclusion, while montelukast can help with allergic conditions and has some effect on eosinophil levels, it is generally not the first-line treatment for conditions with high eosinophilia, where corticosteroids typically show superior efficacy.