Dopamine

Summary

Dopamine is an adrenergic agonist that stimulates the fight or flight response.

At low doses, it activates dopamine receptors, which causes renal artery dilation. At moderate doses, it activates beta-1 receptors, which increases the heart rate and causes positive inotropy, leading to an overall  increase in cardiac output. At high doses, dopamine activates alpha-1 receptors, causing vasoconstriction and increased blood pressure.

Dopamine is used clinically to treat shock and heart failure.

One potential side effect of dopamine is tachycardia. Extravasation of the drug can cause tissue necrosis around the IV site. If this occurs, you can expect to treat extravasation with phentolamine. Other side effects include arrhythmias and chest pain.

Key Points

• Dopamine (Intropin)
  • Mechanism
    • Adrenergic Agonist (stimulates the adrenergic receptors)
      • Low Doses
        • Activates dopamine receptors
          • Renal vasodilation
            • Dopamine type 1 receptors can be found in the kidneys, and when stimulated, the renal blood vessels dilate, increasing renal blood flow and glomerular filtration rate
      • Moderate Doses
        • Activates beta-1 receptors
          • Increases myocardial contraction (positive inotrope)
            • Increases the force of contraction of the heart muscle, which improves cardiac output
          • Increases heart rate
            • Also improves cardiac output
          • Increases cardiac output
      • High Doses
        • Activates alpha-1 receptors
          • Vasoconstriction
            • Causes constriction of blood vessels, leading to increased systemic vascular resistance
          • Increases blood pressure
            • The vasoconstriction and increased systemic vascular resistance lead to an increase in blood pressure
  • Clinical Use
    • Treats shock
      • Shock occurs from lack of blood flow to essential body tissues and organs, leading to inadequate oxygen delivery and cellular dysfunction
      • Through increasing heart contraction, increasing heart rate, and increasing blood pressure, dopamine is effective in increasing cardiac output and improving tissue perfusion in shock states
    • Treats heart failure
      • In heart failure, the heart is unable to pump effectively, leading to decreased cardiac output and tissue perfusion
      • Dopamine improves overall cardiac function by increasing myocardial contraction and heart rate, while also increasing renal perfusion (at low doses) to support kidney function
  • Side Effects
    • Cardiac complications
      • Arrhythmias
        • Dopamine can precipitate or exacerbate cardiac arrhythmias, particularly at higher doses
      • Angina
        • Dopamine can increase myocardial oxygen demand, potentially leading to angina (chest pain)
      • Tachycardia
        • The increase in heart rate can become excessive, leading to tachycardia, especially at moderate to high doses
    • Tissue necrosis around IV site
      • Extravasation (leakage from the vein into surrounding tissue) of dopamine can cause death of the surrounding tissue due to its vasoconstrictive effects
      • If this occurs, treat with phentolamine
        • Phentolamine is an alpha-adrenergic blocker that can counteract the vasoconstrictive effects of dopamine and prevent or limit tissue necrosis