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 Lopressor
, respectively, by Novartis
, and Toprol-XL
(in the USA); Selokeen
(in Nederlands); as Minax
(in Australia), Metrol
by Arrow Pharmaceuticals (in Australia), as Betaloc
, as Neobloc
by Unipharm (in Israel) and as Corvitol
by Berlin-Chemie AG
. 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
Metoprolol is very low melting. Its melting point is around 45 degrees Celsius (as determined by Differential scanning calorimetry). For this reason metoprolol is always manufactured in salt form, 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.
- 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
- Essential hypertension
- Coronary heart disease (prevention of angina attacks)
- Secondary prevention after a myocardial infarction
- Treatment of heart failure.
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.
Transient effects include dizziness, lightheadedness, drowsiness, tiredness, diarrhea, unusual dreams, ataxia, trouble sleeping, 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, trouble breathing, cough, 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, severe dizziness. Taking it with alcohol might cause mild body rashes and therefore is not recommended.