Esmolol, sold under the brand name Brevibloc, is a cardio selective beta₁ receptor blocker with rapid

onset Onset may refer to: Music *Onset (audio), the beginning of a musical note or sound *Interonset interval, a term in music Phonetics and phonology *Syllable onset, a term in phonetics and phonology Etc. *Onset, Massachusetts, village in the Unit ...

, a very short

duration of action Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms (fo ...

, and no significant intrinsic sympathomimetic or membrane stabilising activity at therapeutic dosages. It is a class II

antiarrhythmic Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a class of drugs that are used to suppress abnormally fast rhythms (tachycardias), such as atrial fibrillation, supraventricular tachycardia and ventricular tachycardia. M ...

. Esmolol decreases the force and rate of heart contractions by blocking beta-adrenergic receptors of the

sympathetic nervous system The sympathetic nervous system (SNS or SANS, sympathetic autonomic nervous system, to differentiate it from the somatic nervous system) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous sy ...

, which are found in the

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

and other organs of the body. Esmolol prevents the action of two naturally occurring substances:

epinephrine Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands a ...

and

norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic compound, organic chemical in the catecholamine family that functions in the brain and human body, body as a hormone, neurotransmitter and neuromodulator. The ...

. It was patented in 1980 and approved for medical use in 1987.

Medical uses

To terminate

supraventricular tachycardia Supraventricular tachycardia (SVT) is an umbrella term for fast heart rhythms arising from the upper part of the heart. This is in contrast to the other group of fast heart rhythms – ventricular tachycardia, which start within the lower cham ...

, Episodic atrial fibrillation or flutter, Arrhythmia during anaesthesia, To reduce HR and BP during and after cardiac surgery, and In early treatment of myocardial infarction. Esmolol is also used in blunting the hemodynamic response to laryngoscopy and intubation.

Pharmacology

Pharmacodynamics

Esmolol is a

beta blocker Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms ( arrhythmia), and to protect the heart from a second heart attack after a first heart attack ( secondary prevention ...

, or an

antagonist An antagonist is a character in a story who is presented as the main enemy or rival of the protagonist and is often depicted as a villain.β-adrenergic receptor The adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) produced by the body, but also many medications like bet ...

s. It is selective for the β₁-adrenergic receptor and has no

intrinsic sympathomimetic activity Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms (arrhythmia), and to protect the heart from a second heart attack after a first heart attack (secondary prevention). ...

Pharmacokinetics

Esmolol is considered a soft drug, one that is rapidly metabolized to an inactive form. Esmolol is rapidly metabolized by hydrolysis of the ester linkage, chiefly by the esterases in the cytosol of red blood cells and not by plasma cholinesterases or red cell membrane acetylcholinesterase. Total body clearance in man was found to be about 20 L/kg/hr, which is greater than cardiac output; thus the metabolism of esmolol is not limited by the rate of blood flow to metabolizing tissues such as the liver or affected by hepatic or renal blood flow. Esmolol's short duration of action is based on the

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated as ...

side chain which allows for quick hydrolysis. Esmolol's structure is reflected in its name, es-molol as in ester-methyl. Plasma cholinesterases and red cell membrane acetylcholinesterase do not have any action. This metabolism results in the formation of a free acid and

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...

. The amount of methanol produced is similar to endogenous methanol production. Esmolol has a rapid distribution half-life of about two minutes and an elimination half-life of about nine minutes. Esmolol is classified as a beta blocker with low

lipophilicity Lipophilicity (from Greek λίπος "fat" and φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are called lipophilic (translated ...

and hence lower potential for crossing the

blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that regulates the transfer of solutes and chemicals between the circulatory system and the central nervous system ...

. This in turn may result in fewer effects in the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

as well as a lower risk of

neuropsychiatric Neuropsychiatry is a branch of medicine that deals with psychiatry as it relates to neurology, in an effort to understand and attribute behavior to the interaction of neurobiology and social psychology factors. Within neuropsychiatry, the mind i ...

side effects.

References

{{Portal bar , Medicine Beta blockers N-isopropyl-phenoxypropanolamines Carboxylate esters Diseases of the aorta Methyl esters Peripherally selective drugs