Pharmacology · single question
What is the mechanism of action of ALBUTEROL?
Show answer and explanation
Correct answer: D. Beta-2 adrenergic receptor agonist — relaxes bronchial smooth muscle
Albuterol (salbutamol) is a selective BETA-2 adrenergic receptor AGONIST. It binds to β₂ receptors on bronchial smooth muscle, activating adenylyl cyclase → increased cAMP → protein kinase A activation → smooth muscle relaxation → BRONCHODILATION. Used for acute asthma attacks. Dental relevance: patients with asthma should have their inhaler available during dental appointments.
- A. CORRECT. Albuterol is a β₂ agonist that relaxes airway smooth muscle, causing rapid bronchodilation — the mechanism of its bronchodilatory effect.
- B. Incorrect. β₁ agonism (heart) increases heart rate and contractility — albuterol is selective for β₂ (lung), though some β₁ effects can occur at higher doses.
- C. Incorrect. Muscarinic antagonists (ipratropium/tiotropium) cause bronchodilation by blocking acetylcholine-induced bronchoconstriction — a different mechanism.
- D. Incorrect. Leukotriene receptor antagonists (montelukast/zafirlukast) are used for chronic asthma prevention, not acute bronchodilation — different drug class.