Medicine & USMLE


Sympathomimetics and Sympatholytics (New)
  1. Isoproterenol
  2. Dobutamine
  3. Norepinephrine
  4. Alpha-Methyldopa
  5. Midodrine
  6. Clonidine & Guanfacine
  7. Phenylephrine


Dobutamine is a sympathomimetic drug that stimulates the body’s fight or flight response. At low doses, dobutamine activates beta-1 receptors. At high doses, dobutamine activates beta-2 receptors and alpha receptors. The physiologic effects of administering dobutamine include an increase in heart rate and an increase in inotropy of the heart, both of which lead to an overall increase in cardiac output. Dobutamine may or may not lower blood pressure depending on the dosage given and the patient’s cardiovascular condition. Clinically, dobutamine is used for cardiac stress testing, and may also be used to treat acute heart failure and cardiogenic shock.

Key Points

  • Dobutamine
    • Drug Class
      • Sympathomimetic
        • Mimics the actions of sympathetic hormones to stimulate the fight or flight response
    • Site of Action
      • Agonist at Beta-1 > Beta 2, Alpha
        • Activates predominantly beta-1 receptors at lower doses
        • Activates beta-2 and alpha receptors at higher doses
    • Mechanisms
      • Positive inotropy (increased contractility)
        • This is the primary action of beta-1 agonism at the heart
      • Increases Heart Rate
        • Due to beta-1 receptor effect on increasing chronotropy at SA node
      • Increases Cardiac Output
        • Due to increases in contractility and heart rate
      • May or May Not Reduce Blood Pressure
        • Due to counteracting forces of beta-2 agonism (vasodilation), beta-1 agonism (increased cardiac output), and alpha agonism (vasoconstriction)
    • Clinical Use
      • Used for Cardiac Stress Testing
        • Causes positive inotropy (increased contractility) and may increase cardiac oxygen demand, which is useful for pharmacologic stress testing
      • Treats acute heart failure
        • Used for acute management of LV dysfunction with hypoperfusion
      • Treats cardiogenic shock
        • Can increase cardiac output with very little vasodilation