Esmolol

• Esmolol is a very short acting, cardioselective beta-adrenergic receptor antagonist.
• i.v. administration is used for rapid beta-receptor blockade in treatment of atrial fibrillation with high ventricular following rates.
• Antiarrhythmic effects are due mainly to beta-adrenergic receptor blockade. Normally, sympathetic drive results in increased in Ca²⁺ ,K⁺and Cl^- currents.
• Increased sympathetic tone also increases phase 4 depolarization (heart rate goes up), and increases DAD (delayed afterdepolarizations) and EAD (early afterdepolarization) mediated arrhythmias. These effects are blocked by beta-adrenergic receptor blockers.
• Beta-adrenergic receptor blockers
  • increase AV conduction time
  • increase AV nodal refractoriness, thereby helping to terminate nodal reentrant arrhythmias.

Hondeghem, L.M. and Roden, D.M., "Agents Used in Cardiac Arrhythmias", in Basic and Clinical Pharmacology, Katzung, B.G., editor, Appleton & Lange, 1998, pp 216-241; Stoelting, R.K., "Cardiac Antidysrhythmic Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 331-343

Category: Pharmacology Notes