Description

Montelukast sodium is an oral medication that belongs to a class of drugs called leukotriene receptor antagonists (LTRAs). It is a highly potent and selective agent that targets the inflammatory pathways involved in asthma and allergic rhinitis. It is not a bronchodilator for the immediate relief of asthma attacks but is used for long-term maintenance and prevention of symptoms. It is available in various oral formulations, including tablets, chewable tablets, and granules.

Indication

Montelukast is indicated for the treatment of several conditions, often as part of a long-term management plan:

• Asthma: It is used as a maintenance treatment for the prevention and long-term control of asthma in adults and children (typically 12 months of age and older). It helps to prevent symptoms like wheezing and shortness of breath and to reduce the frequency of asthma attacks.

• Exercise-Induced Bronchoconstriction (EIB): It is indicated for the prevention of EIB in adults and children who are at least 6 years of age.

• Allergic Rhinitis: It is used for the relief of symptoms of seasonal allergic rhinitis in adults and children (2 years of age and older) and perennial allergic rhinitis in adults and children (6 months of age and older).

Mechanism of Action

Montelukast’s mechanism of action is based on its ability to block the effects of leukotrienes, which are potent inflammatory mediators released during an allergic or asthmatic reaction. The process is as follows:

1. Leukotriene Synthesis: During an allergic or asthmatic trigger (e.g., an allergen, exercise), mast cells and eosinophils in the airways and nasal passages produce and release leukotrienes, specifically cysteinyl leukotrienes (LTC4​, LTD4​, LTE4​).
2. Receptor Antagonism: These leukotrienes then bind to and activate cysteinyl leukotriene receptors (CysLT1​) on various cells, including smooth muscle cells in the airways. This activation triggers a cascade of inflammatory responses, including:
   • Bronchoconstriction: The smooth muscles in the airways contract, leading to a narrowing of the airways.

• • Increased Mucus Secretion: Mucus production increases, further obstructing the airways.

• • Airway Inflammation and Edema: The airways become inflamed and swollen.

3. Montelukast’s Action: Montelukast is a potent and selectiveCysLT1​ receptor antagonist. It binds to these receptors with high affinity, effectively blocking leukotrienes from binding and activating them.

4. Symptom Prevention: By blocking theCysLT1​ receptors, montelukast prevents the inflammatory and bronchoconstrictor effects of leukotrienes. This leads to reduced airway inflammation, decreased bronchoconstriction, and less mucus production, thereby helping to prevent asthma symptoms and control allergic rhinitis.