Metoprolol

Metoprolol is a drug that belongs to the class of beta-blockers. It is widely used to treat various cardiovascular diseases. Metoprolol is often used to reduce heart rate, lower blood pressure and control heart rhythm.

Metoprolol is available in various forms, including oral tablets and intravenous injections. It is important to note that the use of metoprolol should be supervised by a physician and adhere to recommended dosages, as misuse or discontinuation can have serious consequences.

Indications Metoprolol

1. Hypertension (high blood pressure): Metoprolol is used to lower blood pressure in patients with hypertension. It helps reduce the risk of cardiovascular complications such as myocardial infarction, stroke and kidney failure.
2. Angina (coronary heart disease): Metoprolol may be prescribed to treat stable and unstable angina (angina pectoris) to reduce the frequency and intensity of attacks chest pain.
3. Heart Failure: In some patients with heart failure, metoprolol may be used to improve heart function and reduce symptoms such as shortness of breath and swelling.
4. Post-infarction: Metoprolol may be used as part of comprehensive treatment after myocardial infarction to reduce the risk of re-infarction and mortality.
5. Cardiac arrhythmias: The drug may be used to control heart rhythm in patients with various arrhythmias such as atrial fibrillation or tachycardia.
6. Prevention migraine: In some patients with frequent migraines, metoprolol may be prescribed as a preventive treatment to reduce the frequency and severity of migraine attacks.

Release form

1. Immediate-release tablets: These tablets are designed for quick relief of symptoms and require several doses throughout the day. They are usually used to correct blood pressure and manage certain heart conditions.
2. Extended-release tablets: This form of metoprolol has been developed to provide a more even release of the active ingredient throughout the day, reducing the frequency of dosing to once daily. This may increase convenience and patient compliance with treatment recommendations.
3. Solution for Injection: Metoprolol in the form of injection is usually used in hospital settings for the rapid correction of certain cardiac conditions, such as severe angina, myocardial infarction, or certain types of arrhythmias.

Pharmacodynamics

1. Selective blocking of β1-adrenoreceptors: Metoprolol mainly blocks β1-adrenoreceptors, which are located in the heart muscle. This allows it to lower the heart rate, thus reducing contractility and the rate of impulse conduction in the heart.
2. Decrease in cardiac output: Blocking β1-adrenoreceptors in the heart muscle leads to a decrease in cardiac contractility and, consequently, to a decrease in cardiac output. This leads to a decrease in blood pressure and the workload of the heart.
3. Reduction of myocardial contractility: Metoprolol reduces the force of contraction of the heart muscle, which leads to a decrease in myocardial oxygen and energy demand, which is especially important in ischemic heart conditions.
4. Reduction of sympathetic activity: Blocking β1-adrenoreceptors also leads to a decrease in sympathetic nervous system activity, which in turn can reduce heart rate and blood pressure.
5. Antiarrhythmic Action: Metoprolol may prevent certain types of arrhythmias, such as tachycardia and atrial fibrillation, due to its ability to reduce heart rate and decrease myocardial excitability.
6. Antianginal action: Blocking β1-adrenoreceptors allows to reduce the load on the heart and improve its perfusion, which may help in the treatment of angina pectoris and reduce the risk of ischemic complications.

Pharmacokinetics

1. Absorption: Metoprolol is usually rapidly and completely absorbed from the gastrointestinal tract after oral administration. Food intake may slow the rate of absorption but usually does not affect total absorption.
2. Distribution: Metoprolol has a low degree of binding to blood plasma proteins (about 10-30%), which ensures its uniform distribution throughout the body.
3. Metabolism: Most of metoprolol is metabolized in the liver to form active metabolites, including α-hydroxymethoprolol and others. These metabolites also have β-adrenoblocking activity.
4. Excretion: Metoprolol and its metabolites are eliminated from the body mainly through the kidneys (approximately 95% of the dose) and to a lesser extent through the intestine.
5. Half-life: The half-life of metoprolol is about 3-7 hours in healthy patients, but may increase in patients with impaired hepatic or renal function.
6. Mechanism of Action: Metoprolol blocks β1-adrenoreceptors, resulting in a decrease in heart rate, heart contraction force, and myocardial contractility, which reduces the heart's oxygen demand and lowers blood pressure.

Dosing and administration

Metoprolol immediate-release (tablets)

• High blood pressure: The starting dose is usually 100 mg per day in one or two doses. Depending on the response to treatment, the dose can be gradually increased at intervals of several weeks. The maximum dose usually does not exceed 450 mg per day.
• Angina pectoris: The initial dose is usually 100 mg per day in two doses. The dose can be gradually increased until the desired effect is achieved, but not more than 400 mg per day.
• Cardiac arrhythmias and prevention of myocardial infarction: Dosage is determined individually based on your condition.

Metoprolol extended-release (tablets)

• This form is usually taken once a day. The starting dose for the treatment of high blood pressure or angina pectoris is usually 25-100 mg per day. Depending on the response to treatment, the dose can be increased gradually.

Solution for injection

• It is used mainly in hospitals for emergency treatment of certain cardiac conditions. The dosage and route of administration depend on the specific medical case.

Important notes

• Do not stop taking metoprolol suddenly, as this may cause your condition to worsen. Any changes in treatment should be made under the strict supervision of your doctor.
• Taking metoprolol may be accompanied by side effects such as fatigue, dizziness, and coldness in the extremities. Tell your doctor if these or other side effects become burdensome.
• Metoprolol may interact with other medications, vitamins, and supplements, so it is important to tell your doctor about any medications you are taking.

Use Metoprolol during pregnancy

The use of metoprolol during pregnancy requires special attention. In general, beta-blockers, including metoprolol, may affect the fetus and the pregnant woman, especially with prolonged use in the third trimester. Some studies have linked the use of beta-blockers during pregnancy to the risk of low birth weight, hypoglycemia in the newborn and other complications.

However, in some cases, if a woman has a serious heart condition that requires metoprolol to manage, her doctor may decide that the potential benefits of the drug outweigh the potential risks to the fetus. In these situations, it is important to carefully discuss all the possible risks and benefits of using metoprolol during pregnancy with your doctor.

Contraindications

1. Allergic Reaction: People with known hypersensitivity to metoprolol or other beta-adrenoblockers should not use it as it may cause allergic reactions.
2. Bradycardia: Metoprolol may decrease heart rate and its use may be contraindicated in people with a very low heart rate (bradycardia).
3. Asthma and chronic obstructive pulmonary disease (COPD): Beta-adrenoblockers, including metoprolol, may worsen symptoms of asthma or COPD because they may contribute to narrowing of the airways.
4. Low blood pressure: Metoprolol can lower blood pressure and its use may be contraindicated in people with low blood pressure.
5. Acute cardiac injury (shock): Metoprolol may be contraindicated in acute heart failure or cardiogenic shock because it may worsen the contractile function of the heart.
6. Cardiac blockade: Metoprolol may increase blockade of conduction of electrical impulses in the heart and may be contraindicated in AV conduction blockade.
7. Pregnancy: The use of metoprolol during pregnancy may require extreme caution and should be taken only when strictly medically indicated and under the supervision of a physician.
8. Breastfeeding: Metoprolol may be excreted into breast milk, therefore its use in breastfeeding may require benefit-risk assessment and should be used with caution under medical supervision.

Side effects Metoprolol

1. Lowering blood pressure: This is one of the desired effects in the treatment of hypertension, but sometimes metoprolol can cause too great a drop in blood pressure, resulting in dizziness, weakness, or even loss of consciousness.
2. Bradycardia (decreased heart rate): Metoprolol may slow your heart rate, which may cause a feeling of palpitations, fatigue, or dizziness.
3. Drowsiness and fatigue: Some patients may experience drowsiness or fatigue while taking metoprolol.
4. Insomnia: Metoprolol may cause insomnia or sleep disturbances in some people.
5. Depression: Some patients may experience mood changes, including depression or anxiety, while taking metoprolol.
6. Stomach problems: Metoprolol may cause dry mouth, nausea, vomiting, diarrhea, or constipation.
7. Peripheral edema: In some patients, metoprolol may cause swelling in the legs or arms.
8. Dyspepsia: This can include a variety of gastrointestinal symptoms such as abdominal discomfort, heartburn or belching.

Overdose

1. Decreased heart rate (bradycardia): An overdose of metoprolol can cause a severe slowing of the heart rate, which can be dangerous, especially for people with an already reduced heart rate.
2. Cardiac arrhythmias: Include various heart rhythm disorders such as ventricular tachycardia, atrial fibrillation and others that can lead to serious complications including cardiac arrest.
3. Decreased blood pressure (hypotension): Metoprolol overdose can cause a drop in blood pressure, which can lead to dizziness, weakness, fainting, and even shock.
4. Peripheral vasodilation (vasodilation): This may lead to a decrease in peripheral vascular resistance and reduced perfusion of organs and tissues.
5. Respiratory depression: In severe overdose, respiratory problems, including respiratory failure, may occur.
6. Other symptoms: Include nausea, vomiting, loss of consciousness, seizures, and others.

Interactions with other drugs

1. Other antihypertensive drugs: Metoprolol may increase the hypotensive effect of other antihypertensive drugs, such as diuretics or angiotensin-converting enzyme inhibitors (ACEIs), which may cause blood pressure to drop to dangerous levels.
2. Antiarrhythmic drugs: Co-administration of metoprolol with antiarrhythmic drugs such as amidarone or class Ic drugs (e.g., propafenone) may increase the depressive effect on cardiac conduction and cause serious arrhythmias.
3. Sympathomimetics: Drugs that stimulate the sympathetic system (e.g. Adrenaline or phenylephrine) may weaken the hypotensive effect of metoprolol and lead to an increase in blood pressure.
4. Non-selective β-adrenoblockers: Co-administration of metoprolol with non-selective β-adrenoblockers such as propranolol may result in increased undesirable side effects such as bradycardia and bronchospasm.
5. Cytochrome P450 inhibitors: Drugs that inhibit cytochrome P450, such as cimedine or ketoconazole, may increase the blood concentration of metoprolol and increase its depressant effect on the cardiovascular system.
6. Monoamine oxidase inhibitors (MAOIs): Use of metoprolol with MAOIs may increase the hypotensive effect and cause serious adverse reactions such as hypotension and orthostatic collapse.

Storage conditions

1. Temperature: Metoprolol should usually be stored at room temperature, which is 15 to 30 degrees Celsius (59 to 86 degrees Fahrenheit).
2. Dryness: The drug should be stored in a dry place to avoid moisture, which may affect its stability and quality.
3. Light: Metoprolol should be stored in a dark place protected from direct sunlight, as light may cause decomposition of the active ingredients.
4. Children: Keep metoprolol out of the reach of children to prevent accidental use.
5. Packaging: Follow the instructions on the package or your doctor's instructions regarding storage of metoprolol.