Beta blockers are drugs that selectively act on beta-adrenergic receptors and block them selectively (selective beta blockers), or all types of adrenergic receptors (nonselective beta blockers).
Read also Beta Blockers Drug Information
Blockade of beta-adrenergic receptors leads to the following effects:
- reduction in heart rate;
- reduction in blood pressure;
- reduction in stroke volume and, consequently, in the minute volume of blood flow (the amount of blood pumped by the heart in 1 minute);
- all the three above effects reduce the work of the heart and, consequently, reduce the need of myocardium (heart muscle) for oxygen;
- reduction in the level of catecholamines (epinephrine, norepinephrine) in the blood;
- reduction in the concentration of renin in the blood plasma (and thus the major internal system of the body that regulates blood pressure – renin-angiotensin-aldosterone system – is blocked);
- membrane stabilizing effect on the cells of the cardiac conduction system, and leveling of the arrhythmogenic effects of catecholamines;
- limiting the spread of ischemic focus (the area of the heart muscle that is subjected to oxygen starvation).
- Marked decrease in heart rate.
- Intracardiac blockade.
- Sharp drop in blood pressure.
- Exacerbation of heart failure.
- Deterioration of the course of accompanying obstructive pulmonary disease (chronic bronchitis, bronchial asthma, emphysema)..
- Severe withdrawal syndrome (risk of renewed pain in the heart, development of arrhythmias when you withdraw from taking the drug, especially pronounced in the case of abrupt withdrawal).
- Narrowing of the peripheral vessels, therefore, there may be trophic disorders in patients with pathologically changed blood vessels. In others, narrowing of blood vessels can lead to cold extremities extremities (hands, feet). For the same reason, there may be worsening of Raynaud’s disease, vibration disease, and intermittent claudication.
- Fall in blood sugar levels, which is especially dangerous when suffering from diabetes, because it can lead to serious complications down to hypoglycemic coma, since despite the fact that people suffering from diabetes are more resistant to the metabolic side effects of beta blockers, tachycardia, usually accompanying a fall in blood sugar, is leveled during the intake of beta blockers.
- Weakness, dizziness, diarrhea, nausea. You should be careful if you have to drive a car or your work involves a great need for attention.
- Orthostatic hypotension (sudden drop in blood pressure when changing the body position – for example, when standing up).
- The pulmonary effects of the blockade of beta-2 adrenergic receptors (bronchospasm) are especially adverse for persons with obstructive pulmonary disease.
Most common side effects of beta blockers
The first four side effects are particularly pronounced when using beta blockers in high doses.
Less common side effects of beta blockers
- Headache, sleep disorder, occurrence of nightmares (especially characteristic of liposoluble beta blockers such as metoprolol and propranolol, which can easily penetrate into the brain).
- Depressive disorders – are one of the inevitable consequences of treatment with beta blockers. The probable cause of this condition is that beta blockers block the synthesis of the “happiness hormone” – serotonin and dopamine – in the central nervous system.
- Atherogenic effect under long-term use of the drug: the level of “harmful” low-density lipoproteins and triglycerides increases in the blood, while the atherogenicity coefficient increases. Therefore, this property of beta-adrenergic blockers limits their long-term use in young people prone to hyperlipoproteinemia.
- Enhancement of the course of allergic reactions to other medications, and in the event of an anaphylactic shock – a reduction in the effectiveness of the most important drug for relief of anaphylaxis – epinephrine.
- Allergic reactions directly to beta-adrenergic blocking agents: skin rashes, laryngospasm, hyperthermia.
- Blurring; of visual fields, burning and stinging in the eye, the “dry eye” effect – these side effects are often characteristic of topical application of beta blockers in ophthalmic practice.
- Development of agranulocytosis and thrombocytopenia.
- Some studies state that the use of beta blockers together with diuretics as the primary therapy for arterial hypertension contributes to the development of diabetes in these patients.
Side effects of beta-adrenergic blocking agents in children and infants:
Beta blockers can worsen uteroplacental blood flow and, consequently, leading to a state of uteroplacental insufficiency. Due to their ability to penetrate through the placental barrier, beta blockers have a teratogenic effect on the developing fetus in the early stages of pregnancy, and fetodepressive (that is, depresses the fetus) effect in the later stages. This is manifested in the form of reduction in the heart rate of the newborn, polycythemia, hypoglycemia, and depression in the newborn.
In older children, beta blockers can slow down physical activity by reducing the heart rate, and in many instances repeat the same side effects as in adults.
Side effects in the elderly:
It is believed that because of the anatomical and physiological characteristics of the body of the elderly, the risk of complications of therapy with beta-adrenergic blocking agents increases, the frequency of side effects significantly increases as well. For example, due to a reduction in the compensatory function of the cardiovascular system in the elderly, dizziness and orthostatic hypotension are more frequent. However, taking of beta blockers by elderly patients is justified, since the mortality rate among people older than 80 years, who had a heart attack is by 32% lower than in those not taking beta-adrenergic blocking agents.
Side effects in men
During treatment with beta blockers, sexual dysfunction often arises – there is a risk of impotence. Decrease in sexual desire (libido) is also a typical side effect of beta blockers.
Side effects in women
There are cases of decreased libido in women taking beta blockers.