Isoproterenol

Overview
  • Isoproterenol is a direct adrenergic agonist that predominantly and non-selectively stimulates beta receptors with almost no alpha receptor activity.
Pharmacological Targets
  • Isoproterenol non-selectively binds and stimulates beta1 and beta2 adrenergic receptors. There is little activity on alpha receptors.
Pharmacological Effects
  • Vascular Effects
    • Because of its potent beta2 receptor activity, isoproterenol leads to vasodilation and thus decreased systemic vascular resistance (SVR).
  • Cardiac Effects
    • Stimulation of cardiac beta1 receptors leads to increased heart rate and contractility, yielding enhanced cardiac output.
  • Blood Pressure Effects
    • Isoproterenol's effect on the blood pressure is a result of its tendency to decrease SVR in the context of increased cardiac output. While the increased cardiac output modestly raises systolic systemic arterial pressure, the decreased SVR leads to greater declines in diastolic pressures, typically leading to modest declines in mean arterial pressure.
  • Respiratory Effects
    • Potent beta2 receptor activity leads to bronchodilation and reduced airflow resistance in the lungs
Therapeutic Uses
  • Although historically used to stimulate cardiac activity, isoproterenol is now rarely used clinically and is mentioned here largely for its educational value as a non-selective beta agonist.