Allergic Rhinitis and Co-morbid asthma: Consideration of Fexofenadin and Montelukast Combination

Allergic rhinitis (AR), a prevalent non-infectious disease condition; is an IgE-mediated response to allergens, causing symptoms like sneezing, rhino rhea, itching, and nasal obstruction. AR significantly contributes to global morbidity and hampers the quality of life. Asthma,characterized by persistent bronchial airway inflammation, manifests with recurrent respiratory symptoms such as wheezing, shortness of breath, chest tightness or cough, and variable airflow limitation. AR and asthma are both systemic conditions with AR being a primary predisposing factor, which often coexists with asthma.

Epidemiology and Key Determinants of Allergic Rhinitis (AR) and Asthma:

Asthma affects approximately up to 18% of the global population (2), while AR impacts nearly 40% of individuals. Notably,over 75% of asthma patients exhibit AR, regardless of its allergic or non-allergic nature. Conversely, up to 40% of those with AR may also have asthma. Asthma tends to be more prevalent in individuals with moderate-to-severepersistent rhinitis than other allergic rhinitis. The ARIA Asia-Pacific workshop report highlights a substantial correlation between AR and asthma in India, indicating coexistence rates of 75% in children and 80% among adults.The CARAS survey revealed a 65.24% prevalence of coexisting AR among 1161asthmatic patients across 10 Indian cities. The study also noted a greater occurrence of concomitant AR and asthma in males than females, emphasising the relevance of allergic sensitisation to various allergens and exposure totrigger factors.

The International Study on Asthma and Allergies in Childhood (ISAAC) identified multiple risk factors for asthma and AR, including maternal smoking, sedentary lifestyle, and paracetamol use during infancy, exposure to pollution, male gender, and being under weight at birth.

Management of Allergic Rhinitis (AR) &co-morbid Asthma:

Individualizing Allergic Rhinitis (AR) therapy is essential, considering the level of disease control and assessment of ongoing treatments. Similarly, asthma-related AR treatment follows a step wise approach(step up or step down), with modifications made based on the degree of disease control. Primary therapeutic options for AR encompass anti-histamines (AH), leukotrienereceptor antagonists (LRA), and cortico steroids, fixed combinations of steroids and anti-histamines, and topical hormones.

Fexofenadine and Montelukast: Practical Pharmacology Glance

Fexofenadine, a second-generation antihistamine(AH) of the piper dine class, acts as an inverse agonist at the H1 receptor,binding to its inactive form for antihistaminic effects. It undergoes minimalhepatic metabolism (<5%) and primarily unchanged urinary excretion, reducing the risk of hepatic cytochrome P (CYP)-mediated interactions. Itsmulti-location H1 receptor binding leads to prolonged dissociation times,extending its duration of action. Moreover, its hydrophilicity prevents easy passage through the blood-brain barrier.

Montelukast, a highly selective leukotriene receptor antagonist (LTRA), exhibits a strong affinity for cysteinylleukotriene receptors, particularly leukotrienes D4 and E4. By binding withhigh affinity, it reduces eosinophil recruitment and activation in the airwaysand suppresses the release of pro-inflammatory cytokines from airway cells.Montelukast's anti-inflammatory effects include reducing sputum eosinophiliaand inflammatory cells in airway mucosa, complementing with other anti-allergicagents like antihistamines.

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