Metoprolol is a selective β1 receptor blocker
Beta blocker
Beta blockers or beta-adrenergic blocking agents, beta-adrenergic antagonists, beta-adrenoreceptor antagonists or beta antagonists, are a class of drugs used for various indications. They are particularly for the management of cardiac arrhythmias, cardioprotection after myocardial infarction ,...

 used in treatment of several diseases of the cardiovascular system, especially hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

. The active substance metoprolol is employed either as metoprolol succinate
Succinic acid
Succinic acid is a dicarboxylic acid. Succinate plays a biochemical role in the citric acid cycle. The name derives from Latin succinum, meaning amber, from which the acid may be obtained....

or metoprolol tartrate
A tartrate is a salt or ester of the organic compound tartaric acid, a dicarboxylic acid. Its formula is O−OC-CH-CH-COO− or C4H4O62−.As food additives, tartrates are used as antioxidants, acidity regulators, and emulsifiers...

(where 100 mg metoprolol tartrate corresponds to 95 mg metoprolol succinate). The tartrate is an immediate-release and the succinate is an extended-release formulation
Pharmaceutical formulation
Pharmaceutical formulation, in pharmaceutics, is the process in which different chemical substances, including the active drug, are combined to produce a final medicinal product.-Stages and timeline:...


Medical uses

Metoprolol is used for a number of conditions including: hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

, angina
Angina pectoris, commonly known as angina, is chest pain due to ischemia of the heart muscle, generally due to obstruction or spasm of the coronary arteries . Coronary artery disease, the main cause of angina, is due to atherosclerosis of the cardiac arteries...

, acute myocardial infarction, supraventricular tachycardia
Supraventricular tachycardia
Supraventricular tachycardia is a general term that refers to any rapid heart rhythm originating above the ventricular tissue. Supraventricular tachycardias can be contrasted to the potentially more dangerous ventricular tachycardias - rapid rhythms that originate within the ventricular...

, ventricular tachycardia
Ventricular tachycardia
Ventricular tachycardia is a tachycardia, or fast heart rhythm, that originates in one of the ventricles of the heart...

, congestive heart failure
Congestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...

, and prevention of migraine headaches.
  • Treatment of heart failure.
  • Vasovagal syncope
    Vasovagal syncope
    A vasovagal episode or vasovagal response or vasovagal attack is a malaise mediated by the vagus nerve. When it leads to syncope or "fainting", it is called a vasovagal syncope, which is the most common type of fainting.There are a number of different syncope syndromes which all fall under the...

  • Adjunct in treatment of hyperthyroidism
    Hyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones . Hyperthyroidism is thus a cause of thyrotoxicosis, the clinical condition of increased thyroid hormones in the blood. Hyperthyroidism and thyrotoxicosis are not synonymous...

  • Long QT syndrome
    Long QT syndrome
    The long QT syndrome is a rare inborn heart condition in which delayed repolarization of the heart following a heartbeat increases the risk of episodes of torsade de pointes . These episodes may lead to palpitations, fainting and sudden death due to ventricular fibrillation...

    , especially for patients with asthma, as metoprolol's β1 selectivity tends to interfere less with asthma drugs which are often β2-adrenergic receptor-agonist drugs

Due to its selectivity in blocking the beta1
Beta-1 adrenergic receptor
The beta-1 adrenergic receptor , also known as ADRB1, is a beta-adrenergic receptor, and also denotes the human gene encoding it...

 receptors in the heart, metoprolol is also prescribed for off-label use in performance anxiety, social anxiety disorder
Social anxiety disorder
Social anxiety disorder , also known as social phobia, is an anxiety disorder characterized by intense fear in social situations causing considerable distress and impaired ability to function in at least some parts of daily life...

, and other anxiety disorder
Anxiety disorder
Anxiety disorder is a blanket term covering several different forms of abnormal and pathological fear and anxiety. Conditions now considered anxiety disorders only came under the aegis of psychiatry at the end of the 19th century. Gelder, Mayou & Geddes explains that anxiety disorders are...



Metoprolol undergoes a-hydroxylation and O-demethylation as a substrate of the cytochrome liver enzymes CYP2D6
Cytochrome P450 2D6 , a member of the cytochrome P450 mixed-function oxidase system, is one of the most important enzymes involved in the metabolism of xenobiotics in the body. Also, many substances are bioactivated by CYP2D6 to form their active compounds...

  and a small percentage by CYP3A4
Cytochrome P450 3A4 , a member of the cytochrome P450 mixed-function oxidase system, is one of the most important enzymes involved in the metabolism of xenobiotics in the body. CYP3A4 is involved in the oxidation of the largest range of substrates of all the CYPs. As a result, CYP3A4 is present in...


Adverse effects

Side effects, especially with higher dosages, include the following: dizziness, drowsiness, fatigue, diarrhea, unusual dreams, ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...

, trouble sleeping, depression, and vision problems. It may also reduce blood flow to the hands and feet, causing them to feel numb and cold; smoking may worsen this effect.

Serious side effects which are advised to be reported immediately include, but are not limited to, symptoms of bradycardia
Bradycardia , in the context of adult medicine, is the resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. It may cause cardiac arrest in some patients, because those with bradycardia may not be pumping enough oxygen to their heart...

 (a very slow heartbeat (less than 50 bpm)), persistent symptoms of dizziness, fainting and unusual fatigue, bluish discoloration of the fingers and toes, numbness/tingling/swelling of the hands or feet, sexual dysfunction
Sexual dysfunction
Sexual dysfunction or sexual malfunction refers to a difficulty experienced by an individual or a couple during any stage of a normal sexual activity, including desire, arousal or orgasm....

, erectile dysfunction
Erectile dysfunction
Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....

 (impotence), hair loss, mental/mood changes, depression, trouble breathing, cough, dyslipidemia, and increased thirst. Other highly unlikely symptoms include easy bruising or bleeding, persistent sore throat or fever, yellowing skin or eyes, stomach pain, dark urine, and persistent nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

. Symptoms of an allergic reaction include: rash, itching, swelling, and severe dizziness. Taking it with alcohol might cause mild body rashes and therefore is not recommended.


Metoprolol may worsen the symptoms of heart failure in some patients, who may experience chest pain or discomfort; dilated neck veins; extreme fatigue; irregular breathing; an irregular heartbeat; shortness of breath; swelling of the face, fingers, feet, or lower legs; weight gain; or wheezing.

This medicine may cause changes in blood sugar levels or cover up signs of low blood sugar, such as a rapid pulse rate.

This medicine may cause some people to become less alert than they are normally, making it dangerous for them to drive, use machines, or do other things.


Excessive doses of metoprolol can cause severe hypotension, bradycardia, metabolic acidosis, seizures and cardiorespiratory arrest. Blood or plasma concentrations may be measured to confirm a diagnosis of poisoning in hospitalized patients or to assist in a medicolegal death investigation. Plasma levels are usually less than 200 μg/L during therapeutic administration, but can range from 1-20 mg/L in overdose victims.

Physical properties

Metoprolol has a very low melting point, around 138 °C. Because of this metoprolol is always manufactured in a salt-based solution, as drugs with melting points below 100 °C are difficult to work with in a manufacturing environment. The free base exists as a waxy white solid, and the tartrate salt is finer crystalline material.(Metox-Wockhardt)


  • Selective
  • Moderately lipophilic
    Lipophilicity, , refers to the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. These non-polar solvents are themselves lipophilic — the axiom that like dissolves like generally holds true...

  • Without intrinsic sympathomimetic activity (ISA)
  • With weak membrane stabilizing activity
  • Short half-life, therefore must be taken at least twice daily or as a slow-release
    Slow-release is a strategy in material science in which a chemical compound is introduced into a system at a reduced speed. Slow-release is applied in fertilizers, pesticides and drugs....

  • Decreases heart rate, contractility and cardiac output, therefore decreasing blood pressure
  • Metabolized in the liver to inactive metabolite


Metoprolol, 1-(iso-propylamino)-3-[4′(2-methoxyethyl)phenoxy]-2-propanol, is synthesized by reacting 4-(2-methoxyethyl)phenol with epichlorohydrin
Epichlorohydrin is an organochlorine compound and an epoxide. This is a colorless liquid with a pungent, garlic-like odor, moderately soluble in water, but miscible with most polar organic solvents. Epichlorohydrin is a highly reactive compound and is used in the production of glycerol, plastics,...

 in the presence of a base, isolating 1,2-epoxy-3-[4′(2-methoxyethyl)phenoxy]propane, the subsequent reaction with isopropylamine
Isopropylamine, also called 2-aminopropane, 2-propanamine, monoisopropylamine, and MIPA, is an organic compound, an amine. It is a base, as typical for amines. It is a hygroscopic colorless liquid with ammonia-like odor. Its melting point is −95.2 °C and its boiling point is 32.4 °C. It is miscible...

, gives an opening of the epoxide
An epoxide is a cyclic ether with three ring atoms. This ring approximately defines an equilateral triangle, which makes it highly strained. The strained ring makes epoxides more reactive than other ethers. Simple epoxides are named from the parent compound ethylene oxide or oxirane, such as in...

 ring and leads to the formation of metoprolol.
  • P.A.E. Carlsson, S.A.I. Carlsson, H.R. Corrodi, L.Ek, B.A.H. Ablad, A.E. Brandstrom, (1975).
  • A.E. Brandstrom, P.A.E. Carlsson, S.A.I. Carlsson, H.R. Corrodi, L.Ek,


Brand names

It is marketed under the brand name Lopressor by Novartis
Novartis International AG is a multinational pharmaceutical company based in Basel, Switzerland, ranking number three in sales among the world-wide industry...

, and Toprol-XL (in the USA); Selokeen (in the Netherlands); as Minax by Alphapharm
Alphapharm is a generic drug manufacturing company based in Australia. Alphapharm manufactures many different generic pharmaceutical medicines. It is an owned by Mylan Pharmaceuticals . Alphapharm's logo is a green circle with a white lowercase alpha enclosed. Alphapharm is the greatest sole...

 (in Australia), Metrol by Arrow Pharmaceuticals (in Australia), as Betaloc by AstraZeneca
AstraZeneca plc is a global pharmaceutical and biologics company headquartered in London, United Kingdom. It is the world's seventh-largest pharmaceutical company measured by revenues and has operations in over 100 countries...

, as Bloxan by Krka (company)
Krka (company)
Krka, d.d., Novo mesto is an international generic pharmaceutical company with headquarters in Novo Mesto, Slovenia. It is one of the leading generic pharmaceutical companies in the world. In 2010, the Krka Group’s total sales were worth EUR 1,010.0 million. Over the past five years, average annual...

 (in Slovenia), as Neobloc by Unipharm (in Israel), Presolol by Hemofarm (in Serbia) and as Corvitol by Berlin-Chemie AG (in Germany). In India, this drug is available under the brand names of Metxl, Metolar and Starpress. A number of generic
Generic drug
A generic drug is a drug defined as "a drug product that is comparable to brand/reference listed drug product in dosage form, strength, route of administration, quality and performance characteristics, and intended use." It has also been defined as a term referring to any drug marketed under its...

products are available as well.

External links

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