**Question:** True about zafirlukast is:

A. It is an inhaled medication.
B. It is a beta-blocker.
C. It is an angiotensin-converting enzyme (ACE) inhibitor.
D. It is an angiotensin II receptor antagonist.

**Core Concept:** Zafirlukast is a drug primarily used as a leukotriene receptor antagonist for the treatment of asthma. Leukotrienes are lipid mediators involved in the inflammatory response, particularly in asthma pathogenesis. Leukotriene D4 (LTD4) and leukotriene E4 (LTE4) receptors, particularly the cysteinyl leukotriene receptor 1 (CysLT1), play a crucial role in asthma exacerbation. Zafirlukast is a selective CysLT1 antagonist, preventing the interaction between leukotrienes and their receptors, thus reducing inflammation and bronchoconstriction in asthmatic patients.

**Why the Correct Answer is Right:** Zafirlukast is indeed an example of a leukotriene receptor antagonist, designed to block specific receptors involved in asthma pathogenesis. In this case, the correct answer is D, "It is an angiotensin II receptor antagonist."

Zafirlukast does not belong to the class of medications that target the renin-angiotensin system, such as ACE inhibitors (option C) and angiotensin II receptor antagonists (option D). Instead, zafirlukast is a selective CysLT1 antagonist, inhibiting the action of leukotrienes, which are pro-inflammatory mediators involved in asthma pathogenesis.

**Why Each Wrong Option is Incorrect:**

A. Inhaled medications (option A) are usually administered through a nebulizer or an inhaler, not specific to zafirlukast's pharmacokinetics. Zafirlukast is an oral medication.

B. Beta-blockers (option B) are used to treat hypertension, angina, and other cardiovascular conditions, not asthma. Zafirlukast is a leukotriene receptor antagonist primarily used for asthma treatment.

C. ACE inhibitors (option C) are medications that target the renin-angiotensin system, specifically ACE (angiotensin-converting enzyme). Zafirlukast, on the other hand, is a leukotriene receptor antagonist that inhibits the action of leukotrienes, which are involved in asthma pathogenesis.

D. Angiotensin II receptor antagonists (option D) are medications that target the renin-angiotensin system, specifically angiotensin II receptors. Zafirlukast, as mentioned before, is a leukotriene receptor antagonist that inhibits the action of leukotrienes, which contribute to asthma pathogenesis.

**Clinical Pearls:**

Zafirlukast, an oral medication, is a selective CysLT1 receptor antagonist, which prevents the interaction of leukotrienes with their receptors, thereby reducing inflammation and bronchoconstriction in asthmatic patients. It is essential to understand the appropriate medication