|Systematic (IUPAC) name|
|Trade names||Lopressor, Toprol-xl|
|Licence data||US FDA:|
|Metabolism||Hepatic via CYP2D6, CYP3A4|
|Mol. mass||267.364 g/mol|
|Melt. point||120 °C (248 °F)|
|(what is this?)|
Metoprolol (//, //) is a selective β1 receptor blocker used in treatment of several diseases, especially hypertension. The active substance metoprolol is employed either as metoprolol succinate or as metoprolol tartrate (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.
Common side effects include trouble sleeping, fatigue, feeling fainting, and abdominal discomfort. It is pregnancy category C in the United States and category C in Australia, meaning evidence of harm is possible. It must be used carefully in those with liver problem.
Metoprolol was first made in 1969.
Metoprolol is used for a number of conditions, including hypertension, angina, acute myocardial infarction, supraventricular tachycardia, ventricular tachycardia, congestive heart failure, and prevention of migraine headaches.
- Treatment of heart failure
- Vasovagal syncope
- Adjunct in treatment of hyperthyroidism
- Long QT syndrome, 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
- Prevention of relapse into atrial fibrillation (controlled-release/extended-release form)
Side effects, especially with higher doses, include dizziness, drowsiness, fatigue, diarrhea, unusual dreams, ataxia, 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. Due to the high penetration across the blood-brain barrier, lipophilic beta blockers such as propranolol and metoprolol are more likely than other less lipophilic beta blockers to cause sleep disturbances such as insomnia and vivid dreams and nightmares.
Serious side effects that are advised to be reported immediately include symptoms of bradycardia (resting heart rate slower than 60 beats per minute), 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, erectile dysfunction (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. Symptoms of an allergic reaction include rash, itching, swelling, and severe dizziness. Taking it with alcohol might cause mild body rashes, so 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. It also may cause some people to become less alert than they are normally, making it dangerous for them to drive or use machines.
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.
Metoprolol has a very low melting point, the tartrate's is around 120 °C (248 °F), and the succinate's around 136 °C (277 °F). Because of this, metoprolol is always manufactured in a salt-based solution, as drugs with low melting points 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.
- Moderately lipophilic
- Without intrinsic sympathomimetic activity
- With weak membrane stabilizing activity
- Short half-life, therefore must be taken at least twice daily or as a slow-release preparation
- 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 in the presence of a base, isolating 1,2-epoxy-3-[4′(2-methoxyethyl)phenoxy]propane, the subsequent reaction with isopropylamine, gives an opening of the epoxide 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, U.S. Patent 3,873,600 (1975).
- A. E. Brandstrom, P. A. E. Carlsson, S. A. I. Carlsson, H. R. Corrodi, L. Ek, DE 2106209 (1971).
It is marketed under the brand name Lopressor by Novartis, and Toprol-XL (in the USA); Selokeen (in the Netherlands); as Minax by Alphapharm and Metrol by Arrow Pharmaceuticals (in Australia), as Betaloc by AstraZeneca, as Bloxan by Krka (company) (in Slovenia), as Neobloc by Unipharm (in Israel), Presolol by Hemofarm (in Serbia), and Corvitol by Berlin-Chemie AG (in Germany). In India, this drug is available under the brand names Met-XL, Metolar, Starpress, and Restopress. A number of generic products are available, as well.
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- "Prescribing medicines in pregnancy database". Australian Government. 3 March 2014. Retrieved 22 April 2014.
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- AstraZeneca's page for Toprol-XL
- Novartis's page for Lopressor (PDF)
- U.S. National Library of Medicine: Drug Information Portal - Metoprolol