Treatment and prevention of cardiovascular diseases: beta-blockers
Beta-blockers are drugs that temporarily block different types of adrenergic receptors (β1-, β2-, β3-). In the article we will describe what these remedies are, what is their impact and when they are prescribed diseases.
Fight against heart pathologies
Beta-blockers are of great importance in the treatment of these diseases. This is the only class of cardiological drugs for the development of which the Nobel Prize in the field of medicine was obtained. During its delivery in 1988, the committee noted that these drugs over the past 200 years have been a tremendous breakthrough in the fight against heart disease after the discovery of digitalis. Digitalis preparations belong to the group of glycosides (means "Digoxin", "Strofantin" and others). They have been used since 1785 to treat chronic heart failure.
Classification of drugs: non-selective and selective beta-blockers
A particular tool from the class in question may belong to one of two groups. The drug may have a selective effect. Beta-blockers in this category are capable of blocking β1-adro-receptors. There is no effect on β2-androreceptors, since their blockade is associated with the main side effects characteristic of this group of drugs in general. To selective beta-blockers belong drugs such as Betaxonol, Atenolol, Bisoprolol, Metoprolol. Recently rarely used drugs "Oxprenolol", "Talinolol", "Acebutolol".
Mechanism of action
In the case of the use of drugs in a small dosage, adrenergic receptors belonging to the subgroup "Pj" are blocked. From this it follows that the agents act in organs, tissue structures of which mainly have β1-adrenoreceptors. With an overdose of selective beta-blockers, partial blockage of β2 receptors is also possible. In addition, funds in this category have a greater impact on the reduction of diastolic pressure.In rare cases, cardioselective beta-blockers can cause bronchospasm. Therefore, patients with bronchial asthma should not be treated with these drugs.
Creation history and features
Beta-blockers entered clinical practice 40 years ago. At that time, they were used as antiarrhythmic drugs and in the treatment of angina pectoris. To date, beta-blockers are the most effective drugs that are used to prevent relapse after acute myocardial infarction. They are also effective in the case of primary prevention of complications of the cardiovascular system in the treatment of hypertension. Increased attention to the study of beta-blockers justified itself. The β-receptor blockade has been widely used to restore the health of patients with acute myocardial infarction. Over the past 10 years, drugs have reduced the likelihood of death in chronic heart failure and reduced the number of complications during surgical operations outside the field of cardiology. According to the results of clinical studies, beta-blockers showed high efficacy in the treatment of elderly patients, as well as people with diabetes.According to the results of large-scale epidemiological studies, beta-blockers are used much less frequently than is required in practice. For a deeper introduction of innovations, considerable joint efforts of scientists are needed. It is they who are able to prove the enormous benefits of certain types of beta-blockers and find solutions for complex clinical problems, given the fact that drugs differ in pharmacological properties.
Norepinephrine. Its effect on the body
Noradrenaline is a hormone, a biologically active substance, similar in its action to adrenaline. With it, the blood vessels are constricted, and, as a result, the blood pressure in a person increases. Norepinephrine is of great importance in hypertension, diabetes, atherosclerosis. Its level is able to increase with angina, acute myocardial infarction, chronic heart failure. In the case of a pathological form of sympathetic activity, a number of pathophysiological changes that progress over time appear. As a result, it can be fatal.
Heart rate as a marker for norepinephrine
Doctors determine an increase in sympathetic activity by high heart rate at rest. For twenty years, about 20 studies have been conducted, in which more than 288,000 people took part. As a result, it was found that an increase in the heart rate is an independent factor and can develop various diseases. These include, in particular, such well-known pathologies such as hypertension, diabetes and others. According to the results of epidemiological studies, a group of people with a heart rate in the range of 90-99 beats / min is subject to mortality three times more than a group whose heart rate varies in the region of 60 beats / min. The optimal value is the frequency up to 80 beats / min.
Norepinephrine and beta-blockers
The medications in question are competitive inhibitors that bind the sympathetic nervous system mediator and β-adrenoreceptor. The presence of beta-blockers increases the need for a higher concentration of norepinephrine for the reaction of the characteristic receptor.
The positive effects of drugs
Over a long period of time, a number of studies have been conducted regarding the level of change in norepinephrine. As a result of the use of radioactive substances, spectral analysis and microneurography, it was possible to identify the positive effects that beta-blockers bring. Preparations eliminate these toxic effects:
- Excess calcium in the cytosol.
- Effect on cardiomyocyte cell growth and apoptosis.
- Increase the automatism of myocytes.
- Fibrillatory action.
- Proarrhythmic action.
- Progressive myocardial fibrosis.
- Hypertrophy of the myocardium of the left ventricle.
It would be wrong to assume that any beta-blocker is suitable for the treatment of angina and arrhythmias. There are pharmacological differences between them. And there are a lot of them. When prescribing a particular medication, a specialist must take into account not only the individual characteristics of the patient. Equally important are the properties of a drug. The main characteristics of the tools include selectivity for β-receptors, differences in lipophilicity, pharmacokinetic properties. The choice of a drug for treatment depends on these differences.The strength of the interaction of the drug with a specific receptor determines the concentration of norepinephrine. Therefore, the dose, for example, of such a drug as "Bisoprol" is less than the dosage of the drug "Metpronol". This is due to the fact that the latter's connection with the receptor is not so strong, unlike the first.