**Question:** True about zafirlukast is

A. It is a beta-agonist
B. It is an angiotensin II receptor antagonist
C. It is a selective serotonin reuptake inhibitor
D. It is a calcium channel blocker

**Correct Answer:**

**Core Concept:** Zafirlukast is a medication primarily used for the treatment of asthma. It belongs to a class of drugs called leukotriene receptor antagonists, which are used to manage asthma symptoms by blocking the action of leukotrienes, which are involved in asthma pathogenesis.

**Why the Correct Answer is Right:** Zafirlukast is a specific inhibitor of cysteinyl leukotriene receptor 1 (CysLT1), which is found on the surface of airway smooth muscle cells, blood vessels, and bronchial epithelial cells. By blocking the action of leukotrienes at the receptor level, zafirlukast helps to reduce bronchoconstriction and other asthma symptoms.

**Why Each Wrong Option is Incorrect:**

A. Zafirlukast is not a beta-agonist. Beta-agonists are medications that stimulate beta receptors and are primarily used for their bronchodilator effect in asthma management. Zafirlukast, on the other hand, is a leukotriene receptor antagonist.

B. Zafirlukast is not an angiotensin II receptor antagonist. Angiotensin II receptor antagonists (ARBs) are medications used for hypertension and heart failure primarily by blocking angiotensin II action. Zafirlukast is a leukotriene receptor antagonist, not an ARB.

C. Zafirlukast is not a selective serotonin reuptake inhibitor (SSRI). SSRIs are a class of antidepressants that primarily increase serotonin levels by inhibiting serotonin reuptake. Zafirlukast is a leukotriene receptor antagonist used in the management of asthma symptoms.

D. Zafirlukast is not a calcium channel blocker. Calcium channel blockers are medications used for hypertension, angina, and heart failure by blocking calcium channels. Zafirlukast is a leukotriene receptor antagonist used in the management of asthma symptoms.

**Clinical Pearl:** Zafirlukast is an effective and well-tolerated medication for the management of asthma symptoms, particularly in patients who do not respond well to beta-agonists. By blocking the action of leukotrienes, zafirlukast helps to reduce airway inflammation and bronchoconstriction, which is a key mechanism in asthma pathogenesis.