Snapshot A 22-year-old woman presents to the emergency department with shortness of breath. She has a history of seasonal allergies and eczema. The patient is tachypneic but is saturating well on room air. Physical exam is notable for bilateral wheezes and poor air movement. The patient is given albuterol and her wheezing decreases and she feels better. (Asthma) introduction One of 7 medications used for asthma aimed to reduce inflammation and obstruction corticosteroids β-agonists muscarinic antagonists methylxanthines antileukotrienes omalizumab Introduction Drugs short-acting, may be used during acute exacerbation albuterol and levalbuterol (β2) asthma COPD terbutaline (β2) asthma (albuterol preferred as first-line) tocolysis in labor metaproterenol (β2 and minor β1) asthma (rarely used) long-acting, prophylaxis only salmeterol and formoterol (β2) asthma/COPD prophylaxis (not initial management for acute flares) Mechanism of action β-2 agonism increases cAMP causing smooth muscle relaxation improving air flow tachycardia when acting on the heart vasodilation when acting on the blood vessels tremor, sweating, anxiety, and agitation when acting systemically intracellular sequestration of potassium β-1 agonism increases cAMP causing the following undesirable side effects cardiac effects tachycardia increased contractility increased cardiac output could increased risk of cardiac dysrhythmias Clinical use asthma COPD bronchospasm from chemical irritation hyperkalemia Adverse effects could be harmful in bronchiolitis tachycardia hypokalemia can cause U-waves on ECG anxiety