Metoprolol

Metoprolol

File:(±)-Metoprolol Structural Formulae.png
Systematic (IUPAC) name
(RS)-1-(isopropylamino)-3-[4-(2-methoxyethyl)phenoxy]propan-2-ol
Clinical data
[[Regulation of therapeutic goods |Template:Engvar data]]	US FDA: Metoprolol
Pregnancy category	AU: C US: C (Risk not ruled out)
Routes of administration	Oral, IV
Legal status
Legal status	℞ (Prescription only)
Pharmacokinetic data
Bioavailability	12%
Metabolism	Hepatic
Biological half-life	3-7 hours
Excretion	Renal
Identifiers
CAS Number	51384-51-1
ATC code	C07AB02 (WHO)
PubChem	CID 4171
IUPHAR/BPS	553
DrugBank	APRD00208
ChemSpider	4027
Chemical data
Formula	C15H25NO3
Molar mass	267.364 g/mol[[]]

"Minax" redirects here. For the Ultima game character, see Minax (Ultima).

Not to be confused with metformin or metropolis.

Metoprolol (pronounced /mɛˈtoʊproʊlɑːl/) is a selective β₁ receptor blocker used in treatment of several diseases of the cardiovascular system, especially hypertension. It is marketed under the brand name Lopresor 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 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 products are available as well. The active substance metoprolol is employed either as metoprolol succinate or metoprolol tartrate (whereas 100 mg metoprolol tartrate corresponds to 95 mg metoprolol succinate), respectively as prolonged-release or conventional-release formulation.

Physical properties

Metoprolol has a very low melting point, around 45 degrees Celsius (as determined by differential scanning calorimetry). Because of this metoprolol is always manufactured in a salt-based solution, as drugs with melting points below 100 degrees Celsius are difficult to work with in a manufacturing environment. The free base exists as a waxy white solid, where the tartrate salt is finer crystalline material. It is metabolized in the liver to inactive metabolites.

Pharmacology

• Selective
• 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

Indications

• Essential hypertension
• Tachycardia
• Coronary heart disease (prevention of angina attacks)
• Secondary prevention after a myocardial infarction
• Treatment of heart failure.
• Migraine prophylaxis
• 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

Due to its selectivity in blocking the beta₁ receptors in the heart, metoprolol is also prescribed for off-label use in performance anxiety, social anxiety disorder, and other anxiety disorders.

File:ToprolXL50mg.png

Toprol XL 50mg

Precautions

Metoprolol may worsen the symptoms of heart failure in some patients. Check with your doctor right away if you are having 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 your blood sugar levels. Also, this medicine may cover up signs of low blood sugar, such as a rapid pulse rate. Check with your doctor if you have these problems or if you notice a change in the results of your blood or urine sugar tests.

This medicine may cause some people to become less alert than they are normally. If this side effect occurs, do not drive, use machines, or do anything else that could be dangerous if you are not alert while taking metoprolol .

Side effects

Transient effects include dizziness, lightheadedness, drowsiness, tiredness, 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.

Serious side effects that are not to be tolerated for any length of time include symptoms of a very slow heartbeat (less than 50 bpm) (e.g. persistent dizziness, fainting, 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.

External links

• AstraZeneca's page for Toprol-XL
• Novartis's page for Lopresor (PDF)
• U.S. National Library of Medicine: Drug Information Portal - Metoprolol

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