In this article, we consider beta-blockers.
A very important role in the regulation of the functions of the human body is played by catecholamines, which are adrenaline and norepinephrine. They are released into the bloodstream and act on particularly sensitive nerve endings called adrenoreceptors. They are divided into two large groups. The first is alpha adrenergic receptors, and the second is beta adrenoreceptors. Beta-adrenergic receptors are found in many human organs and tissues.
A detailed description of this group of drugs
Beta-blockers, or abbreviated as BAB, are a group of drugs that bind beta-adrenergic receptors and inhibit the effects of catecholamines on them. Such preparations are particularly widely applicable in cardiology.
In the case of activation of β1-adrenergic receptors, an increase in the frequency and strength of heart contractions occurs, and in addition, the coronary arteries expand, the level of conduction and automatism of the heart increases. In addition, the breakdown of glycogen in the liver is enhanced and energy is produced.
In the case of excitation of β2-adrenergic receptors, the walls of blood vessels and bronchial muscles relax, uterine tone decreases during pregnancy, insulin secretion increases along with the breakdown of fat. Thus, the process of stimulation of beta-adrenergic receptors by means of catecholamines leads to the mobilization of all forces, which contributes to active life.
The list of new generation beta-blockers drugs will be presented below.
The mechanism of action of drugs
These drugs are able to reduce the frequency along with the strength of the heartbeat, thereby reducing blood pressure. As a result, oxygen consumption by the heart muscle is reduced.
Diastole lengthens - a period of rest and general relaxation of the heart, during which blood vessels are filled. An improvement in coronary perfusion is also facilitated by a decrease in diastolic intracardiac pressure. There is a process of redistribution of blood flow from normally blood-supplying areas to ischemic areas, as a result of which the tolerance of physical activity by a person increases.
Beta-blockers are characterized by antiarrhythmic effects. They are able to suppress the cardiotoxic and arrhythmogenic effects of catecholamines, and in addition, they prevent the accumulation of calcium ions in heart cells, which impair energy metabolism in the myocardium.
The list of beta-blockers is very extensive.
Classification of drugs in this group
The substances presented are a fairly large group of drugs. They are classified according to many signs. Cardioselectivity refers to the ability of a drug to block only β1-adrenergic receptors, without affecting β2-adrenergic receptors located in the vascular and bronchial walls. The greater the selectivity of beta-1-adrenergic blockers, the less danger there is in their use in concomitant pathologies of the respiratory canals and peripheral vessels, and also in diabetes mellitus. But selectivity is a relative concept. In case of prescribing the drug in excessive doses, the degree of selectivity decreases.
Some beta-blockers are characterized by the presence of internal sympathomimetic activity. It lies in the ability to somewhat stimulate beta-adrenergic receptors. Compared with conventional beta-blockers, such drugs slow down heart rhythms and the power of contractions much less, and less often lead to the withdrawal syndrome. In addition, they do not so negatively affect lipid metabolism.
Some selective beta-blockers can additionally dilate blood vessels, that is, endowed with vasodilating properties. This mechanism is usually realized through internal pronounced sympathomimetic activity.
The duration of exposure most often directly depends on the chemical structure of selective and non-selective beta-blockers. Lipophilic drugs can act for several hours and quickly excreted from the body. Hydrophilic drugs, such as Atenolol, are effective for a longer time and can be prescribed less frequently. To date, long-acting lipophilic drugs have been developed, for example, Metoprolol Retard. In addition, there are beta-blockers with a very short duration of exposure, only up to thirty minutes, as an example, the drug "Esmolol".
Non-cardioselective drugs
Non-cardioselective beta-blockers include drugs that do not have internal sympathomimetic activity. These are the following:
- Propranolol-based products, such as Anaprilin and Obzidan.
- Drugs based on nadolol, for example, Korgard.
- Medications based on sotalol: Sotagexal along with Tenzol.
- Means based on timolol, for example, "Blockden".
The list of beta-blockers with sympathomimetic activity includes the following drugs:
- Medicines based on oxprenolol, for example Trazikor.
- Pindolol-based products, such as Wisken.
- Alprenolol-based drugs, for example, Aptin.
- Penbutolol-based medicines, for example Betapressin, along with Levatol.
- Bopindolol-based products, such as Sandonorm.
Among other things, Bucindolol possesses sympathomimetic activity along with Dilevalol, Karteolol and Labetalol.
The list of beta-blockers does not end there.
Cardioselective preparations
The following drugs that do not have internal sympathomimetic activity are referred to cardioselective:
- Medications based on metoprolol, for example Betalok, along with Corvitol, Metozok, Metokard, Metokor, Serdol and Egilok.
- Atenolol-based drugs, for example Betacard along with Stenormin.
- Betaxolol-based products, such as Betac, Carlon and Lokren.
- Esmolol-based medicines, such as Breviblok.
- Preparations based on bisoprolol, for example, Aritel, Bidop, Biol, Biprol, Bisogamma, Bisomor, Concor, Corbis, Cordinorm, Coronal, Niperten and Tirez.
- Carvedilol-based medicines, for example, Acridilol along with Bagodilol, Vedicardol, Dilatrend, Carvedigamm, Carvenal, Coriol, Reckardium and Talliton.
- Preparations based on nebivolol, such as Binelol along with Nebivator, Nebikor, Nebilan, Nebilet, Nebilong and Nevotenz.
The following cardioselective preparations have sympathomimetic activity: “Acecor” along with “Sectral”, “Kordanum” and “Vazakor”.
Let's continue the list of beta-blockers of a new generation.
Medicines with a vasodilating property
Non-cardioselective drugs of this category include such drugs as Amozulalol along with Butsindolol, Dilevalol, Labetolol, Medroxalol, Nipradilol and Pindolol.
Carvedilol, Nebivolol and Celiprolol are equated with cardioselective drugs.
How does the effect of beta-blockers differ?
Long-term exposure agents include Bopindolol, along with Nadolol, Penbutolol and Sotalol. And among beta-blockers with ultra-short action, it is worth calling Esmolol.
Application against angina pectoris
In many cases, such medications are among the leading ones for the treatment of angina pectoris and the prevention of seizures. Differing from nitrates, such drugs do not cause drug resistance against prolonged use. Beta-adrenergic blocking drugs can accumulate in the body, which makes it possible to reduce the dosage of the drug after a while. These medicines protect the heart muscle, improving prognosis by reducing the risk of recurrent heart attack. The antianginal activity of such drugs is the same. They need to be selected depending on the duration of the effect and adverse reactions.
Therapy begins with a small dosage, which is gradually increased to effective. The dose is selected in such a way that the resting heart rate is at least fifty per minute, and the systolic pressure level is at least one hundred millimeters of mercury. Upon reaching the therapeutic effect, angina attacks cease, physical exercise tolerance improves. Against the background of progress, the dosage should be reduced to the minimum effective.
Long-term use of high doses of such drugs is considered impractical, since this increases the risk of adverse reactions. In case of insufficient effectiveness, it is better to combine these drugs with other groups of medicines. Such funds are forbidden to abruptly cancel, since withdrawal syndrome may appear. BAB is especially indicated if angina pectoris is combined with sinus tachycardia, glaucoma, arterial hypertension, or constipation.
The latest beta-blockers are effective for myocardial infarction.
Heart Attack Treatment
Early use of BAB against a heart attack helps to limit cardiac muscle necrosis. At the same time, mortality and the risk of re-infarction are significantly reduced. In addition, the risk of heart failure is reduced.
A similar effect turns out to be drugs without sympathomimetic activity, it is preferable to use cardioselective drugs. They are especially useful in combining a heart attack with ailments such as arterial hypertension, sinus tachycardia, post-infarction angina pectoris, and tachysystolic form of atrial fibrillation.
These drugs can be prescribed to patients immediately upon admission to the hospital, provided that there are no contraindications. In the absence of side effects, treatment should continue for at least a year after a heart attack.
The use of BAB in chronic heart failure
The use of beta-blockers for heart failure is currently being studied. It is believed that they should be used in combination with heart failure and angina pectoris. Pathologies in the form of rhythm disturbances, arterial hypertension, and a tachysystolic form of atrial fibrillation also serve as grounds for prescribing this group of drugs to patients.
Use for hypertension
BAB is prescribed for the treatment of hypertension, which is complicated by ventricular hypertrophy. They are also widely used among young patients who lead an active lifestyle. This category of drugs is prescribed in the case of a combination of arterial hypertension with cardiac arrhythmias, and in addition, after a heart attack.
How else can I use the new generation beta-blockers from the list?
Use for heart rhythm disturbance
BAB is widely used for atrial fibrillation and flutter, and in addition, against the background of poorly tolerated sinus tachycardia. They can be prescribed in the presence of ventricular arrhythmias, however, the effectiveness in this case will be less pronounced. BAB in combination with potassium preparations is used to treat arrhythmias that are caused by glycosidic intoxications.
What are the possible side effects of the heart?
BAB can inhibit the ability of the sinus node to generate impulses that cause heart contractions. These drugs can slow your heart rate to less than fifty per minute. This side effect is less pronounced in BAB with sympathomimetic activity.
Drugs in this category can cause atrioventricular blockade of varying degrees. They reduce the strength of the heartbeat. In addition, BAB lower blood pressure. Medicines in this group cause peripheral vasospasm. Patients may experience a limb cooling. New generation beta-blockers reduce renal blood flow. Due to the deterioration of blood circulation during treatment with these drugs, sometimes patients experience severe weakness.
Adverse reactions from the respiratory system
BAB can cause spasms of the bronchi. This side effect is less pronounced among cardioselective drugs. However, their dosages, which are effective against angina pectoris, are often quite high. The use of high dosages of these drugs can provoke apnea along with temporary respiratory arrest. BAB can worsen the course of an allergic reaction to insect bites, and in addition to drugs and food allergens.
Nervous system reaction
“Propranolol” along with “Metoprolol” and other lipophilic BAB can penetrate into brain cells through the blood-brain barrier. In this regard, they are capable of causing headaches, impaired sleep, dizziness, memory impairment, and depression. In severe cases, hallucinations, convulsions or coma may occur. These adverse reactions are much less pronounced in hydrophilic drugs, in particular, “Atenolol”.
Treatment of BAB is sometimes accompanied by a violation of nerve conduction. This leads to muscle weakness, fatigue and reduced stamina.
Metabolic reaction
Non-selective BAB are able to suppress insulin production. Also, these drugs significantly inhibit the process of mobilization of glucose from the liver, which contributes to the development of protracted hypoglycemia in patients with diabetes. Hypoglycemia, as a rule, promotes the release of adrenaline into the bloodstream, which acts on alpha-adrenergic receptors. This leads to a significant increase in pressure. Therefore, if necessary, prescribe BAB to a patient with concomitant diabetes, it is better to give preference to cardioselective drugs or change them to calcium antagonists.
Many BAB, especially non-selective ones, lower normal cholesterol in the blood and, accordingly, increase the level of bad. True, this drawback is deprived of such drugs as Carvedilol along with Labetolol, Pindolol, Dilevalol and Celiprolol.
What other possible side effects?
Treatment of BAB in some cases may be accompanied by sexual dysfunction, and in addition, erectile dysfunction and loss of sexual desire. To date, the mechanism of this effect is unclear. Among other things, BAB can cause skin changes, which, as a rule, manifests itself in the form of erythema, rash and symptoms of psoriasis. In rare examples, hair loss occurs along with stomatitis. The most serious side effect is the inhibition of hematopoiesis with the occurrence of thrombocytopenic purpura and agranulocytosis.
Next, find out what are the contraindications to the use of beta-blockers.
Contraindications to the use of BAB
Beta-blockers have many different contraindications and are considered completely prohibited in the following situations:
- The appearance of pulmonary edema along with cardiogenic shock.
- The development of severe heart failure.
- The presence of bronchial asthma in patients.
- The presence of a syndrome of weakness of the sinus node.
- The presence of atrioventricular blockade of the second or third degree.
- The presence of a level of systolic pressure equal to one hundred millimeters of mercury and below.
- The presence of a heart rate that is less than fifty per minute.
- The presence of poorly controlled insulin-dependent diabetes mellitus.
Relative contraindication to the prescription of drugs in this category is Raynaud's syndrome along with atherosclerosis of the peripheral arteries, which is accompanied by the occurrence of intermittent claudication.
So, we reviewed the list of beta-blockers. We hope that the information provided was useful to you.