Obstructive pulmonary diseases: The Daily PANCE Blueprint

The answer is B. Salmeterol

Salmeterol (Serevent) is a long-acting beta-2 agonist (LABA) that selectively stimulates beta-2 adrenergic receptors in bronchial smooth muscle, resulting in bronchodilation. Salmeterol has a duration of action of 12 hours, allowing for twice-daily dosing. It is used as a maintenance therapy for asthma and COPD, but must be used with an inhaled corticosteroid in asthma due to safety concerns. Unlike short-acting agents, salmeterol has a slow onset of action (15-20 minutes) but provides prolonged bronchodilation. Its lipophilic side chain allows it to remain anchored to the receptor for extended periods, explaining its long duration of effect.

Incorrect Answer Explanations:

• A. Fluticasone is an inhaled corticosteroid (ICS), not a LABA. It works by reducing airway inflammation through multiple anti-inflammatory mechanisms. It’s often combined with a LABA (like salmeterol in Advair) for enhanced efficacy in asthma and COPD management, but has no direct bronchodilatory effect.
• C. Tiotropium is a long-acting muscarinic antagonist (LAMA), not a LABA. It blocks M3 muscarinic receptors to prevent acetylcholine-induced bronchoconstriction. It has a duration of action of 24+ hours and is primarily used in COPD management, with a different mechanism of action than beta-agonists.
• D. Montelukast is a leukotriene receptor antagonist (LTRA), not a LABA. It blocks leukotriene D4 receptors to reduce airway inflammation. It’s used primarily in asthma management, particularly for exercise-induced and allergic asthma, and works through an anti-inflammatory rather than bronchodilatory mechanism.
• E. Ipratropium is a short-acting muscarinic antagonist (SAMA), not a LABA. It blocks muscarinic receptors with a duration of action of 6-8 hours. While it causes bronchodilation, it does so through a different mechanism than beta-agonists and requires multiple daily doses due to its shorter duration.