Albuterol vs Salmeterol

Summary

Albuterol and Salmeterol are drugs that act as activators of beta-2 receptors. By activating beta-2 receptors, these drugs cause smooth muscle relaxation that notably causes  bronchodilation of the airways.  As such, the inhaled formulations of these drugs can be useful in the treatment of Asthma and COPD. Importantly, Albuterol is short  or fast acting and can be used in the treatment of acute exacerbations, while salmeterol is long or slow acting, making it better for chronic maintenance therapy. 

Both of these drugs can reduce potassium levels in the blood by increasing sequestration of potassium into cells. They may rarely cause other side effects such as tremors, and arrhythmias.

Key Points

• B2 agonists (-erol)
  • Short acting:
    • Albuterol
  • Long-acting:
    • Salmeterol
    • Formoterol
  • Mechanism:
    • Agonist at beta-2 receptors
      • some B1 agonism (B2>>B1)
    • Induces Bronchodilation
      • B2 agonists activate adenylyl cyclase to ↑ cAMP in bronchial smooth muscle, leading to smooth muscle relaxation and dilation of the airways.
    • Sequesters K+ in cells
      • beta-2 agonists activate membrane-bound Na/K-ATPase, causing it to pump excess serum K+ into cells.
  • Indications:
    • Asthma
      • Acute → albuterol
      • Long-term maintenance → salmeterol, formoterol  
    • COPD
      • Acute → albuterol
      • Long-term maintenance → salmeterol, formoterol
    • Hyperkalemia
      • Can be inferred by mechanism
  • Adverse effects:
    • Due to B1 activation
      • Tremor
      • Tachyarrhythmias
    • Due to B2 activation
      • Hypokalemia