## **Core Concept**
Exercise-induced bronchial asthma, also known as exercise-induced bronchospasm (EIB), is a condition where the airways constrict in response to physical exertion. This condition is prevalent among individuals with asthma but can also occur in non-asthmatic individuals. The underlying mechanism involves the release of inflammatory mediators and the contraction of bronchial smooth muscles.

## **Why the Correct Answer is Right**
The correct answer, **C. Montelukast**, is a leukotriene receptor antagonist (LTRA). Montelukast works by blocking the action of leukotrienes, which are chemical messengers involved in the inflammatory process and bronchoconstriction. Leukotrienes are released during exercise in susceptible individuals, contributing to the constriction of airway smooth muscles. By inhibiting the leukotriene pathway, montelukast can effectively prevent exercise-induced bronchospasm.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because the drug listed is not provided, but typically, short-acting beta-agonists (SABAs) like albuterol are used for quick relief of bronchospasm rather than prevention of exercise-induced asthma.
- **Option B:** This option is incorrect because the drug listed is not provided, but generally, antihistamines are not the first line of treatment for preventing exercise-induced bronchial asthma.
- **Option D:** This option is incorrect because the drug listed is not provided, but usually, anticholinergics like ipratropium are more commonly used for COPD and not as a first-line preventive measure for exercise-induced bronchial asthma.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **montelukast**, a leukotriene receptor antagonist, is effective in preventing exercise-induced bronchospasm. It's also worth noting that other preventive measures include using short-acting beta-agonists (SABAs) 15-20 minutes before exercise, and for individuals with more severe symptoms, LABAs (long-acting beta-agonists) or combination therapy with inhaled corticosteroids may be considered.

## **Correct Answer:** . Montelukast