Medicine & USMLE

Beta-2 Agonists (Albuterol, Salmeterol)

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Respiratory Drugs
  1. Beta-2 Agonists (Albuterol, Salmeterol)
  2. Cromolyn
  3. Montelukast
  4. Guaifenesin
  5. Ephedrine / Phenylephrine
  6. Acetylcysteine
  7. Theophylline

Summary

Inhaled beta-2 agonists include the fast-acting albuterol and the slow-acting salmeterol. Both of these drugs are used to treat asthma and COPD. Side effects include tremors, tachycardia, hypokalemia, and CNS stimulation.

Key Points

  • Inhaled Beta-2 Adrenergic Agonists
    • Key Drugs
      • Albuterol
      • Salmeterol
      • Formoterol
      • Levalbuterol
      • Terbutaline (given IV, not inhaled)
    • Mechanism
      • Activate beta-2 adrenergic receptors in the lungs, relaxing the bronchial smooth muscle and causing bronchodilation
    • Clinical Use
      • Asthma
        • Albuterol= acute asthma attacks, short acting
        • Salmeterol = long-term control, long-acting
      • COPD exacerbations (albuterol)
      • Exercise-induced bronchospasm (albuterol)
        • Albuterol can be taken before exercise to prevent exercise-induced bronchospasm
    • Administration
      • Inhaler
        • Shake the medication canister prior to administration
        • A spacer may be used to improve drug delivery to the lung and reduce undesirable side effects
        • When a client is prescribed both a beta-2 agonist and an inhaled glucocorticoid, the beta-2 agonist should be administered first
          • The beta-2 agonist will open the bronchioles, allowing for better absorption of the glucocorticoid
        • Salmeterol inhalers are used every 12 hours for long-term control. They are not used to treat an acute asthma attack.
    • Side Effects and Adverse Reactions
      • Tremors
        • Most common side effect, expected
        • In addition to beta-2 receptors in the lungs, these medications also activate the beta-2 receptors in the skeletal muscle, causing tremors
        • Will usually diminish over time
      • Tachycardia / Palpitations
        • Oral beta-2 adrenergic agonists may also activate the alpha-1 receptors in the heart, causing tachycardia, angina, hypertension, and palpitations
        • Patients should avoid caffeine
        • If this occurs, dosage might need to be reduced
        • Contraindicated in patients with arrhythmia
      • Hypokalemia
        • Albuterol increases potassium uptake by the cells, thus decreasing the amount of potassium in the blood
      • CNS Stimulation
        • Restlessness, agitation, Anxiety, Excitability, Nervousness, Insomnia
      • Hyperglycemia
        • Use with caution in diabetic patients - they may require more insulin than normal