Beta blockers have been used as antihypertensive drugs since the early sixties. From the moment the first results of treatment have been revealed to the present day, their effectiveness has been convincingly proven in numerous controlled studies, as well as when compared with the effects of more modern means.
Beta-blockers have been successfully used to reduce blood pressure and prevent the development of cardiovascular disease and mortality. The mechanism of their antihypertensive action is based on a decrease in cardiac output due to a decrease in the strength and frequency of contraction. In addition, beta-blockers contribute to inhibition of renin secretion in the juxtaglomerular (pericubule) renal apparatus and, in this regard, effective suppression of activity in the renin-angiotensinaldosterone and central vasomotor systems.
Their long-term use can provoke a decrease in vascular resistance (general peripheral), due to increased sensitivity of baroreceptors and the production of prostacyclin (vasodilating prostaglandins) in the vascular wall.
Different beta-blockers used in equivalent doses have a similar antihypertensive effect. Full antihypertensive effect develops in two to four weeks. Against the background of prolonged use, a “withdrawal" syndrome may occur. To prevent it, the drug is not canceled immediately, but the dose is gradually reduced over ten to fourteen days.
The systemic effects of drugs, in particular non-selective ones, can provoke the development of clinically significant extracardial and cardiac side effects.
The first group includes disorders on the psycho-emotional background (depression, sleep disturbance, etc.), respiratory manifestations (bronchospasm), peripheral vasoconstriction (intermittent claudication, cold extremities, etc.), muscle weakness, impotence. Extracardial side effects are impaired renal function caused by a decrease in blood flow in the kidneys, difficulty in lipid and carbohydrate metabolism.
The group of cardiac manifestations includes:
- impaired pumping of cardiac function, accompanied by symptoms of insufficiency;
- blockade (atrioventricular, sinoatrial) of the heart and bradycardia;
- the development of hypotension against the background of an excessive decrease in blood pressure;
- antiarrhythmic effect.
It should be noted that the variety in the pharmacological properties of blockers makes it possible to choose the optimal drug for almost every case. At the same time, treatment tolerance, the lowest risk of side effects, exposure duration and type of clinical situation are taken into account.
The appointment of beta-blockers as the only therapy allows for the normalization of blood pressure in about 40-50% of patients with hypertension. Compared with the effect on patients at a young, middle and older age, the effect is relatively lower in older people. The use of a thiazide diuretic in combination with a beta blocker eliminates the differences. Thus, the effectiveness of therapy with this combination increases to 78-80%.
Beta-blockers for the treatment of angina pectoris occupy a separate place. In this disease, drugs such as Anaprilin (Obzidan), Sotalol, Atenolol, Concor, Monotard are used.
The action of all these medicines is aimed at lowering blood pressure and "lowering" the heart rate. The dosage of any drug should be selected purely individually by the attending physician.
Drugs for bronchial asthma, chronic obstructive pulmonary diseases, atrioventricular blockade of the second or third degrees are contraindicated. The use of beta-blockers is not recommended for impaired glucose tolerance, peripheral artery disease, athletes and physically active individuals.