Esmolol

Drug Information: Esmolol

Detailed information regarding Esmolol, a cardioselective beta-adrenergic blocker. It is primarily used for rapid control of ventricular rate in supraventricular tachycardias (SVT), including atrial fibrillation and atrial flutter, and for rapid heart rate reduction in other conditions where short-term control is desired. Esmolol’s short half-life allows for quick onset and offset of effects, making it ideal for situations requiring precise heart rate management. It is administered intravenously and its effects are usually seen within minutes.

Category

Drugs for ACS

Mechanism of Action

Esmolol is a beta-1 selective adrenergic receptor blocker. Beta-1 receptors are primarily located in the heart. By selectively blocking these receptors, esmolol decreases heart rate, contractility, and conduction velocity, particularly at the sinoatrial (SA) and atrioventricular (AV) nodes. This reduces myocardial oxygen demand. The selectivity for beta-1 receptors is more pronounced at lower doses. However, at higher doses, esmolol can exhibit some beta-2 blocking activity. Due to its ester linkage, esmolol is rapidly metabolized by esterases in red blood cells, resulting in a very short elimination half-life (approximately 9 minutes). This rapid metabolism allows for precise titration of the drug’s effect, making it suitable for situations where quick control and reversibility are desired. The blockade of beta-1 receptors also results in a decrease in renin secretion from the kidneys, contributing to a reduction in blood pressure.

Clinical Uses

Esmolol is primarily used in the management of acute cardiovascular conditions requiring rapid heart rate control. Its applications include:

• Supraventricular Tachycardia (SVT): Esmolol is effective in rapidly reducing ventricular rate in SVT, including atrial fibrillation and atrial flutter.
• Tachycardia and Hypertension During and After Surgery: It can be used to control heart rate and blood pressure elevations associated with surgical procedures.
• Noncompensatory Sinus Tachycardia: Esmolol can be used when rapid heart rate reduction is deemed necessary.
• Acute Myocardial Ischemia: By reducing heart rate and contractility, esmolol can decrease myocardial oxygen demand in patients with acute coronary syndromes (ACS) like unstable angina or myocardial infarction, although it is typically used cautiously in this setting.
• Aortic Dissection: Used to lower heart rate and blood pressure rapidly to reduce stress on the aortic wall.

Dosage

Esmolol is administered intravenously. The dosage is highly individualized based on patient response and the clinical situation. Typical adult dosage regimens involve:

• Loading Dose: 500 mcg/kg IV over 1 minute.
• Maintenance Infusion: Start at 50 mcg/kg/min and titrate upwards as needed, typically in increments of 50 mcg/kg/min every 4 minutes, up to a maximum of 200 mcg/kg/min. Some protocols use higher initial bolus doses (up to 1000 mcg/kg) followed by a maintenance infusion.
• Pediatric Dosage: Limited data is available. Consult specialized references and expert guidance for pediatric dosing. Generally, a similar loading dose of 500 mcg/kg IV over 1 minute is used, followed by a maintenance infusion starting at 25-50 mcg/kg/min and titrating to effect.

Close monitoring of heart rate, blood pressure, and ECG is crucial during esmolol administration. The infusion rate should be adjusted based on the patient’s response and tolerance.

Indications

Common indications for Esmolol include:

• Rapid ventricular rate control in supraventricular tachycardia (SVT).
• Short-term heart rate control in other tachyarrhythmias.
• Tachycardia and/or hypertension during or immediately after surgery.
• Acute myocardial ischemia, specifically to reduce heart rate and myocardial oxygen demand.

Contraindications

Esmolol is contraindicated in:

• Severe bradycardia (heart rate less than 60 bpm).
• Heart block greater than first degree.
• Cardiogenic shock.
• Overt heart failure.
• Hypotension.
• Known hypersensitivity to esmolol or any of its components.
• Sick sinus syndrome (unless a permanent pacemaker is in place).
• Severe peripheral arterial circulatory disturbances.
• Pulmonary hypertension.

FAQ

• Q: What is Esmolol used for?
  
  A: Esmolol is used to rapidly control heart rate in conditions like supraventricular tachycardia (SVT), and to manage hypertension and tachycardia during and after surgery.
• Q: How quickly does Esmolol work?
  
  A: Esmolol has a very rapid onset of action, with effects typically seen within minutes of administration.
• Q: What are the common side effects of Esmolol?
  
  A: Common side effects include hypotension, bradycardia, nausea, and dizziness.
• Q: How is Esmolol administered?
  
  A: Esmolol is administered intravenously, usually with a loading dose followed by a continuous infusion.
• Q: How long does Esmolol stay in the body?
  
  A: Esmolol has a very short half-life (about 9 minutes), meaning its effects wear off quickly after the infusion is stopped.
• Q: Can Esmolol be used in patients with asthma?
  
  A: Esmolol should be used with caution in patients with asthma or other reactive airway diseases, as it can potentially cause bronchospasm. Beta-1 selectivity is lost at higher doses.
• Q: What should I do if a patient becomes hypotensive while on Esmolol?
  
  A: If hypotension occurs, the infusion rate should be decreased or stopped. Fluid boluses and vasopressors may be required.
• Q: Is Esmolol safe to use in patients with heart failure?
  
  A: Esmolol is generally contraindicated in patients with overt heart failure due to its negative inotropic effects.