Esmolol

Esmolol injection is a short-term intravenous treatment used in hospitals to control fast heart rates and high blood pressure in specific clinical situations.

• Control of rapid ventricular rate (the rate at which the lower chambers of the heart beat) in supraventricular tachycardia (SVT), including atrial fibrillation and atrial flutter, in emergency or perioperative settings
• Control of noncompensatory sinus tachycardia (a fast heart rate from the heart's natural pacemaker that requires specific treatment)
• Short-term treatment of tachycardia and high blood pressure occurring during induction of anesthesia, tracheal intubation, surgery, emergence from anesthesia, or in the postoperative period
• Brevibloc injection, Esmolol Hydrochloride injection, Esmolol Hydrochloride In Sodium Chloride injection, and Esmolol Hydrochloride in Water injection are each approved for these same indications — all are intended for short-term, in-hospital use only
• Esmolol is not recommended to prevent tachycardia or high blood pressure before they occur

Esmolol is a cardioselective beta-1 blocker — it primarily targets beta-1 receptors found in the heart muscle. Blocking these receptors slows the heart rate, reduces the force of electrical conduction through the heart's upper and lower chambers, and lowers blood pressure. This makes it effective at calming rapid or irregular rhythms quickly. At higher doses, it can also begin to affect beta-2 receptors in the airways and blood vessels, which is why patients with breathing problems require careful monitoring.

Because esmolol is broken down by enzymes inside red blood cells rather than by the liver, its effects wear off very quickly — usually within 10 to 20 minutes of stopping the infusion. This short action makes it easy for clinicians to precisely control the dose and reverse the effect rapidly if needed.

Esmolol is given only as an intravenous (IV) infusion — always in a monitored hospital or clinical setting, never at home. Clinicians may start with a loading dose to achieve fast heart rate control, followed by a continuous maintenance infusion that is adjusted based on heart rate or blood pressure at regular intervals. The infusion rate and duration are determined by your care team based on your specific condition and response. No food or drink considerations apply since esmolol is given directly into the vein.

• Used for short-term treatment only
• Dose is adjusted every 4 minutes or more based on response
• Effects resolve quickly — usually within 10 to 30 minutes of stopping the infusion

The most common side effects with esmolol injection include:

• Low blood pressure (hypotension) — the most frequent and important side effect; may cause dizziness or sweating; usually reverses when the infusion is reduced or stopped
• Asymptomatic hypotension (low blood pressure without noticeable symptoms)
• Nausea
• Dizziness
• Drowsiness
• Infusion site reactions — redness, swelling, or inflammation where the IV is placed

More serious reactions — including severe low blood pressure, very slow heart rate, heart block, cardiac arrest, bronchospasm, or severe infusion site damage (blistering, tissue death) — require immediate medical attention and may lead to the infusion being stopped.

• Low blood pressure (hypotension): Can occur at any dose but is more likely at higher doses. Severe cases can cause loss of consciousness or cardiac arrest. The infusion will be slowed or stopped if this occurs.
• Slow heart rate (bradycardia) and heart block: Esmolol can cause the heart to beat too slowly, including dangerous pauses or complete heart block. Patients with pre-existing conduction problems are at higher risk.
• Cardiac failure: Esmolol can reduce the heart's pumping strength and may trigger heart failure or cardiogenic shock. The infusion must be stopped at the first sign of this.
• Breathing problems: Patients with asthma or reactive airway disease are at risk of bronchospasm. Esmolol should be used with great caution in these patients, and the infusion stopped immediately if bronchospasm develops.
• Diabetes: Esmolol can hide the fast heart rate that warns of low blood sugar — diabetic patients need careful monitoring.
• Infusion site injury: If the IV leaks, serious skin and tissue damage can result. Small veins should be avoided.
• Stopping esmolol abruptly in patients with coronary artery disease can trigger heart attack, severe angina, or dangerous arrhythmias — heart rate should be monitored when discontinuing.
• Hyperkalemia (high potassium): Esmolol can raise potassium levels, which is potentially life-threatening in patients on hemodialysis.

Esmolol can interact with several medications that also affect the heart, blood pressure, or blood sugar. Key interactions include:

• Digoxin: Combined use raises digoxin blood levels and increases the risk of an excessively slow heart rate
• IV verapamil and other cardiodepressant calcium channel blockers: Combining with esmolol can cause fatal cardiac arrest — these must not be given together or close together in time
• Clonidine, guanfacine, or moxonidine: Stopping these blood pressure medications while on esmolol can cause dangerous rebound high blood pressure — the beta-blocker should be tapered first
• Epinephrine, norepinephrine, and dopamine: Esmolol should not be used to control heart rate in patients already receiving these vasoconstrictive/inotropic drugs due to risk of severely reduced cardiac output
• Succinylcholine and mivacurium (muscle relaxants): Esmolol can prolong the effects of these anesthesia-related drugs
• Other blood pressure-lowering drugs or heart-slowing agents: Additive effects can lead to severe hypotension or bradycardia
• Beta-agonist drugs (e.g., albuterol): These will counteract esmolol's heart-rate-slowing effects

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Do not use esmolol if you have severe sinus bradycardia (very slow heart rate), heart block greater than first degree, or sick sinus syndrome
• Do not use if you have decompensated heart failure, cardiogenic shock, or pulmonary hypertension
• Do not combine esmolol with IV verapamil or similar calcium channel blockers — fatal cardiac arrest has occurred
• Tell your care team if you have asthma, COPD, or any reactive airway disease
• Tell your care team if you have diabetes — esmolol can mask the fast heartbeat that signals low blood sugar
• Tell your team if you have coronary artery disease, Prinzmetal's angina, peripheral circulatory disorders (including Raynaud's disease), or pheochromocytoma
• Pregnancy: Esmolol should only be used during pregnancy if the benefit clearly outweighs the risk; use near delivery has been linked to fetal bradycardia
• Breastfeeding: It is unknown whether esmolol passes into breast milk — weigh the benefit to the mother against potential risk to the infant
• Children: Safety and effectiveness in pediatric patients have not been established
• Older adults: Start at the lower end of the dose range; older patients are more likely to have kidney, heart, or other conditions that increase sensitivity to esmolol
• Kidney impairment: No dose adjustment is needed for standard short infusions, but there is limited information about higher doses or longer infusions in patients with kidney disease
• Liver impairment: No special precautions needed, as esmolol is broken down by red blood cell enzymes rather than the liver

Too much esmolol can cause serious heart and nervous system problems, including a dangerously slow heart rate, heart block, low blood pressure, cardiac arrest, respiratory depression, seizures, and coma — and can be fatal. Because esmolol clears from the body in about 9 minutes, the first step in managing an overdose is to stop the infusion immediately, after which effects typically begin to resolve quickly.

Dilution errors have been the cause of some accidental overdoses, some of which have been fatal — emphasizing the importance of careful preparation and monitoring in clinical settings.

Esmolol slows heart rate both at rest and during activity, reduces the strength of heart muscle contractions, and lowers blood pressure. It also slows electrical conduction through the heart's AV node (the gateway between upper and lower chambers), which helps control rapid rhythms like atrial fibrillation. After the infusion is stopped, most of these effects reverse within 10 to 20 minutes.

Esmolol works very quickly after the IV infusion starts and is broken down rapidly — primarily by enzymes inside red blood cells, not by the liver. Its elimination half-life (the time it takes for half the drug to clear) is only about 9 minutes, meaning it leaves the body much faster than most beta-blockers. Less than 2% of the drug is excreted unchanged in the urine; the main breakdown product is an inactive acid metabolite that leaves the body via the kidneys over several hours. Because it is cleared so quickly, the infusion rate can be adjusted or stopped to rapidly change the drug's effect.

Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° and 30°C (59° and 86°F). Protect from freezing. Avoid excessive heat.