|Systematic (IUPAC) name|
|Trade names||Lopressor, Toprol-xl|
|Licence data||US FDA:|
|Pregnancy cat.||C (AU) C (US)|
|Legal status||℞ Prescription only|
|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 of the cardiovascular system, 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.
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 dosages, include the following: 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, but are not limited to, 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 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.
Metoprolol has a very low melting point, tartrate around 120°C, succinate around 136°C. 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.(Metox-Wockhardt)
- Moderately lipophilic
- 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 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).
Cortel M combination of Amlodipine and Metoprolol with 25 and 50 mg claim for Metoproplol(Corona - India)
It is marketed under the brand name Lopressor by Novartis, and Toprol-XL (in the USA); Selokeen (in the Netherlands); as Minax by Alphapharm (in Australia), 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 as Corvitol by Berlin-Chemie AG (in Germany). In India, this drug is available under the brand names of Met-XL, Metolar and Starpress,Restopress. A number of generic products are available as well.
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- MERIT-HF Study Group (1999). "Effect of metoprolol CR/XL in chronic heart failure: Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF)". Lancet 353 (9169): 2001–2007. doi:10.1016/S0140-6736(99)04440-2. PMID 10376614.
- Biffi, M.; Boriani, G.; Sabbatani, P.; Bronzetti, G.; Frabetti, L.; Zannoli, R.; Branzi, A.; Magnani, B. (Mar 1997). "Malignant vasovagal syncope: a randomised trial of metoprolol and clonidine.". Heart 77 (3): 268–72. doi:10.1136/hrt.77.3.268. PMID 9093048.
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- "Metoprolol". Drugs.com.
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- "Metoprolol (Oral Route) Precautions". Drug Information. Mayo Clinic.
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- Baselt R (2008). Disposition of Toxic Drugs and Chemicals in Man (8th ed.). Foster City, CA: Biomedical Publications. pp. 1023–1025.
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- Blake, CM.; Kharasch, ED.; Schwab, M.; Nagele, P. (Sep 2013). "A meta-analysis of CYP2D6 metabolizer phenotype and metoprolol pharmacokinetics.". Clin Pharmacol Ther 94 (3): 394–9. doi:10.1038/clpt.2013.96. PMID 23665868.
- AstraZeneca's page for Toprol-XL
- Novartis's page for Lopressor (PDF)
- U.S. National Library of Medicine: Drug Information Portal - Metoprolol