Generic Name: Esmolol.

Trade Name    : Brevibloc.

Drug Class      : Selective Beta-Adrenoceptor Antagonist ,  Antidysrhythmics.

Forms of The Drug

  1. Infusion Bags: 2g/100mL – 2.5g/250mL.
  2. Injectable Solution: 10mg/mL – 20mg/mL.

Mechanism of Action

Esmolol is a medication classified as a selective beta-1 adrenergic receptor antagonist, also known as a beta-blocker. Its mechanism of action involves blocking the effects of the neurotransmitter epinephrine (adrenaline) on the beta-1 receptors primarily located in the heart.

When administered intravenously, esmolol rapidly reaches its target receptors and competitively binds to the beta-1 adrenergic receptors in cardiac tissue. By doing so, it prevents the binding of epinephrine and norepinephrine to these receptors. This blockade of beta-1 receptors leads to several physiological effects:

  1. Heart Rate Reduction: Esmolol decreases the heart rate by blocking the stimulatory effect of epinephrine on the beta-1 receptors in the sinoatrial (SA) node, which is responsible for initiating the electrical impulses that regulate the heart rhythm. By slowing down the heart rate, esmolol can be useful in conditions where a rapid heart rate needs to be controlled, such as supraventricular tachycardia or atrial fibrillation.
  2. Decreased Contractility: Esmolol decreases the force of contraction of the heart muscle by blocking beta-1 receptors in the myocardium (heart muscle). This reduces the workload on the heart and can be beneficial in conditions such as hypertension (high blood pressure) or myocardial infarction (heart attack).
  3. Reduced Conduction Velocity: Esmolol can slow down the electrical conduction within the heart by blocking beta-1 receptors in the atrioventricular (AV) node. This effect is useful in conditions where abnormal electrical impulses need to be controlled, such as atrial fibrillation with rapid ventricular response or certain types of supraventricular tachycardia.


  1. Supraventricular tachycardia (SVT).
  2. Atrial fibrillation and atrial flutter.
  3. Hypertensive emergencies.
  4. Intraoperative hypertension or tachycardia.
  5. Myocardial infarction.


  1. Sinus bradycardia and heart block.
  2. Cardiogenic shock.
  3. Severe asthma or chronic obstructive pulmonary disease (COPD).
  4. Hypersensitivity.
  5. Decompensated heart failure.
  6. Second- or third-degree atrioventricular (AV) block without a functioning pacemaker.

Side Effects

  1. Hypotension, asymptomatic (25-38%).
  2. Hypotension, symptomatic (12%).
  3. Injection site pain (8%).
  4. Nausea (7%).
  5. Dizziness (3%).
  6. Somnolence (3%).
  7. Agitation (2%).
  8. Confusion(2%).
  9. Headache (2%).
  10. Fatigue (1%).
  11. Vomiting (1%).

Drug Interactions

Other drugs that can interact with it.

  1. Calcium channel blockers, such as diltiazem or verapamil.
  2. Digoxin.
  3. Antiarrhythmic drugs, such as amiodarone or quinidine.
  4. Anesthetics.
  5. Other beta-blockers.
  6. Sympathomimetic drugs, such as epinephrine or norepinephrine.


  1. Pregnancy: Category C, especially in 2nd and 3rd trimesters.
  2. Lactation: Limited information is available regarding the excretion of esmolol into breast milk and its effects on breastfeeding infants. As a result, caution is generally advised when considering the use of esmolol during lactation.

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