Esmolol

Mechanism :

Similar to other beta-blockers, esmolol blocks the agonistic effect of the sympathetic neurotransmitters by competing for receptor binding sites. Because it predominantly blocks the beta-1 receptors in cardiac tissue, it is said to be cardioselective. In general, so-called cardioselective beta-blockers are relatively cardioselective; at lower doses they block beta-1 receptors only but begin to block beta-2 receptors as the dose increases. At therapeutic dosages, esmolol does not have intrinsic sympathomimetic activity (ISA) or membrane-stabilizing (quinidine-like) activity. Antiarrhythmic activity is due to blockade of adrenergic stimulation of cardiac pacemaker potentials. In the Vaughan Williams classification of antiarrhythmics, beta-blockers are considered to be class II agents.

Indication :

• Supraventricular Tachycardia
• Perioperative Tachycardia and Hypertension

Contraindications :

Hypersensitivity and Asthma/COPD.

Sinus bradycardia, 2°/3° heart block, cardiogenic shock, overt cardiac failure.

Sick sinus syndrome without permanent pacemaker.

Dosing :

Adverse Effect :

Diaphoresis, dizziness, peripheral ischemia, bradycardia, flushing, chest pain, pallor, syncope, pulmonary edema, heart block, nausea, dyspepsia, weakness, dizziness, somnolence, headache, bronchospasm, depression.

Interaction :

Digitalis glycosides: Concomitant administration of digoxin and esmolol leads to an approximate 10% to 20% increase of digoxin blood levels at some time points. Digoxin does not affect esmolol pharmacokinetics. Both digoxin and beta blockers slow atrioventricular conduction and decrease heart rate. Concomitant use increases the risk of bradycardia.
Anticholinesterases: Esmolol prolonged the duration of succinylcholine-induced neuromuscular blockade and moderately prolonged clinical duration and recovery index of mivacurium.
Antihypertensive Agents Clonidine, Guanfacine, or Moxonidine: Beta blockers also increase the risk of clonidine-, guanfacine-, or moxonidine-withdrawal rebound hypertension. If, during concomitant use of a beta blocker, antihypertensive therapy needs to be interrupted or discontinued, discontinue the beta blocker first, and the discontinuation should be gradual.
Calcium Channel Antagonists: In patients with depressed myocardial infarction, use of esmolol with cardio depressant calcium channel antagonists (e.g., verapamil) can lead to fatal cardiac arrests.
Sympathomimetic Drugs: Sympathomimetic drugs having beta-adrenergic agonist activity will counteract effects of esmolol.
Vasoconstrictive and Positive Inotropic Agents: Because of the risk of reducing cardiac contractility in presence of high systemic vascular resistance, do not use esmolol to control tachycardia in patients receiving drugs that are vasoconstrictive and have positive inotropic effects, such as epinephrine, norepinephrine, and dopamine.

Renal Dose :

Hepatic Dose :