Dopamine

Summary

Dopamine is a catecholamine used as a drug for various clinical uses. Dopamine primarily works by activating adrenergic receptors in the arteries in order to cause vasoconstriction, which has the overall effect of increasing blood pressure. Since dopamine increases blood pressure, it can be used to treat hypotension and shock. Dopamine also works on adrenergic receptors at the heart to increase the heart rate, which is useful in the treatment of bradycardia. Dopamine can cause local tissue death at the IV site if it leaks or extravasates, so the IV site should be closely monitored. Phentolamine can be injected as an antidote if extravasation does occur.

Key Points

• Mechanism
  • Adrenergic agonist
    • At intermediate doses, dopamine stimulates the beta-1 receptors in the heart, which increases heart rate and increases myocardial contractility
      • Positive inotrope and chronotrope
    • At high doses, dopamine also stimulates the alpha-adrenergic receptors which are located in the arteries, causing vasoconstriction, and thus increasing blood pressure
  • Clinical Use
    • Hypotension (e.g. shock)
      • Blood pressure is increased due to vasoconstriction, as well as stronger and faster contractions of the heart
      • If patient is hypovolemic, adequate fluid/blood product resuscitation is required prior to dopamine
    • (Symptomatic) Bradycardia
      • Second line drug, used when atropine is not effective
      • Heart rate is increased as a direct result of activation of the beta-1 receptors
    • Renal vasodilation
      • In very small doses, dopamine dilates the renal arteries, increasing urine output
  • Side Effects and Adverse Reactions
    • Tissue death (necrosis) around injection site
      • Due to drug-induced vasoconstriction causing poor tissue perfusion
      • Phentolamine is antidote for acute vasoconstriction, which should be injected into the site if extravasation occurs
    • Myocardial ischemia
      • Due to vasoconstrictive effects
    • Cardiac distress
      • Tachycardia, arrhythmias, palpitations may result due to dopamine’s effects on increasing HR
    • Nausea and vomiting
    • Do not run dopamine and bicarbonate in the same IV line, as bicarbonate inactivates dopamine