Biochemistry seems daunting, but it does not have to be complicated. You’re probably here to learn about beta-blockers without having experience in biochemistry. But that’s fine.
In this article, we will break down the topic in easily digestible pieces.
By the last paragraphs of the article, you will end up discovering why your doctor prescribed them. You will know how they help, their side effects, and natural alternatives.
What Are Beta-Blockers?
Unlike alpha-blockers, beta-blocker drugs are defined as antagonist agents of the beta-adrenergic system.
The adrenergic system is composed of adrenaline and noradrenaline. They are also known as epinephrine and norepinephrine.
These drugs compete with epinephrine and norepinephrine by blocking their receptors in the cell.
There are different types of beta-blockers, depending on the type of receptor they block. For example, we have non-selective beta-blockers that interact with all kinds of beta-receptors.
But, we can also have selective β1 and selective β2 blockers. The former works in the cardiovascular system while the latter is better for a few other physiologic functions.
How Do Beta-Blockers Work?
Beta-blockers work by preventing adrenaline and noradrenaline from stimulating cells in the body.
Adrenaline and noradrenaline work in different tissues by increasing our heart rhythm, our blood pressure, and favoring contraction in the smooth muscle.
They do this by taking the place of adrenaline and noradrenaline in the cell receptors to block them. Thus, they reduce the heart rhythm, blood pressure, and the contraction of certain muscles (1).
They are divided into three types:
- Non-selective beta-blockers: Propanolol, carvedilol, labetalol. They interact with all types of beta-receptors. Non-selective beta-blockers cause a reduction in blood pressure. They also work in the smooth muscle of various tissues throughout the body.
- Selective β1 blockers: Nebivolol (Bystolic), atenolol, bisoprolol, metoprolol. They only interact with β1 receptors. Thus, their function is limited to the cardiovascular system.
- Selective β2 blockers: Butaxamine. They only interact with β2 receptors. Therefore, their role includes vasodilation, relaxation of smooth muscle in the uterus, and much more.
As you will see in the next section, these medications are beneficial in cases of hypertension, in cases of left ventricular hypertrophy, coronary artery disease, in some instances of atrial fibrillation, and to prevent migraine headaches.
What Do Beta-Blockers Do?
Depending on the type, each one of them will be useful in different health problems.
By occupying β1 receptors, beta-blockers work by reducing our blood pressure and heart rate.
By occupying β2 receptors, beta-blockers work by relaxing smooth muscle in the uterus, dilating the respiratory tree, and favoring blood flow to the kidneys and liver.
Selective beta-blockers work in one type of receptor, either β1 or β2. They have selective functions but may lose their selectivity in high doses. Non-selective beta-blockers work in both β1 and β2 receptors at the same time, at any dose.
What Are Beta-Blockers Used To Treat?
Beta-blockers can treat several conditions:
Patients with tachycardia should be examined to determine the root cause. In most cases, it is caused either by anxiety or ventricular arrhythmias. In every case, they are useful in reducing the frequency and severity of tachycardia episodes (2).
Beta-blockers lessen the exposure of the cardiovascular system to adrenaline and its effects. Thus, these medications reduce the fight-or-flight effect of adrenaline in the cardiovascular system. It reduces blood pressure, and it is sometimes used as a therapy for hypertension. In these cases, it goes along with dietary changes and exercise recommendations (3).
Doctors may need to use beta-blockers in cases of chest pain due to myocardial infarction. They do so to reduce the infarct size and the mortality rate. Early administration results in a better prognosis of patients with myocardial infarction (4).
Congestive heart failure
In cases of systolic heart failure, beta-blockers slow down the progression of the disease. One of the beta-blockers approved in these cases is nebivolol or any other β1 selective medication. They are indicated in cases of left ventricular systolic dysfunction with no symptoms or mild to moderate symptoms. They usually complement with diuretics or angiotensin-converting enzyme inhibitors, also known as ACE inhibitors (5).
Beta-blockers are very useful in certain types of arrhythmias, including atrial fibrillation. Supraventricular tachycardia (SVT) may result in arrhythmia episodes, and beta-blockers reduce their incidence. They are also indicated in ventricular tachyarrhythmia. They may also be useful for treatment or prevention (6).
Coronary artery disease
Patients with angina and previous myocardial infarction may find beta-blockers helpful. These drugs are first-line prophylactic agents in cases of coronary artery disease. It may be useful for asymptomatic patients, as well (7).
Patients with symptomatic hyperthyroidism usually have tachycardia and tremors. In these cases, beta-blockers work by reducing the heart rate and the symptoms of anxiety.
Besides tremors in patients with hyperthyroidism, we can also have essential tremors. It is a neurologic disorder caused by drugs, brain injury, and other triggers. In these cases, propranolol is the first-line therapy, but other non-selective beta-blockers may be used. That includes nadolol and sotalol (8).
It is a condition featuring an injury to the inner lining of the aorta. The blood starts to flow, in-between the layers of the aorta wall, forcing the layers apart. These patients need to control their hypertension, and beta-blockers are commonly used for that purpose (9).
It is an increase in portal vein pressure, common in cases of cirrhosis. Beta-blockers are used widely in these cases to reduce portal pressure. One of the most favorable beta-blockers is carvedilol. This drug reduces portal pressure and favors intrahepatic vasodilation (10).
Beta-blockers can be administered through ocular drops in order to improve cases of glaucoma.
Migraine headache prophylaxis
Beta-blockers are useful to prevent cases of migraine and tension headaches in adults. Especially propranolol. It does so by reducing blood pressure in the blood vessels running through the meninges (11).
In Which Situations Are Beta-Blockers The Best Treatment Choice?
Choosing one treatment over the other depends on the patient and his symptoms. However, beta-blockers are useful as the best treatment choice in these cases:
It is an episode of extremely high levels of thyroid hormone in the blood. It usually has cardiovascular complications. Beta-blockers are the best treatment in these cases. They control blood pressure and reduce anxiety levels.
It is a type of tumor that continuously releases adrenaline to the bloodstream. It is controlled through a combination of propranolol and alpha-blocker therapy.
Similar to the above, essential tremors are controlled by using beta-blockers, especially propranolol.
Beta-blocker agents for cardiac arrhythmia include sotalol and esmolol.
Congestive heart failure
In congestive heart failure, the best beta-blockers are carvedilol and metoprolol.
Patients with glaucoma usually receive beta-blocker drops. These contain betaxolol, levobunolol, metipranolol, or timolol.
In patients with myocardial infarction, the best choice is propranolol or metoprolol. Carvedilol can be used as well, especially in patients with ventricular dysfunction.
Hypertension is not listed because, even though beta-blockers are useful to reduce blood pressure, they are not the first treatment choice.
Side Effects Of Beta-Blockers
Similar to many other drugs, beta-blockers have side effects we should keep in mind.
Remember that not every patient will develop these side effects, and some of them are quite rare. Thus, we are going to break the downside effects of beta-blockers in two different groups:
- Serious side effects: They include side effects that may cause severe or life-threatening health issues.
- Common side effects: The most common side effects when beta-blockers are correctly prescribed. These are not usually severe, as you will see.
What are the most severe side effects of beta-blockers?
Side effects appear in patients with particular ailments, and cases of high doses. This is a list of the most serious side effects of beta-blockers, and in what type of patients they usually appear.
In the respiratory tree, adrenaline has the effect of expanding the bronchi to let more air come through.
People with asthma usually require beta-agonists because they have the same function of adrenaline. Thus, administering beta-blockers instead of beta-agonists has the potential to precipitate asthma attacks or aggravate the symptoms.
That does not necessarily mean that asthma is a contraindication of beta-blockers. We have cardioselective beta-blockers (Selective β1 blockers). They are safe to use with no added risk in patients with moderate or severe exacerbations of asthma (12).
Memory loss and confusion
Noradrenaline does not only work in the cardiovascular system. It is also useful in the brain as a neurotransmitter. Noradrenaline is essential to retrieve memories by activating β1 receptors located in the hippocampus.
Thus, patients taking beta-blockers may have memory loss as a side effect. It can aggravate cognitive problems and delayed memory function. (13).
Bradycardia and heart dysfunction
All beta-blockers inhibit adrenaline signals to the cardiovascular system. This causes a reduction in the heart rate, which makes it useful for tachycardia.
But an excessive dose of beta-blockers may result in bradycardia, an abnormal reduction of the heart rate. Similarly, beta-blockers are not to be used in acute heart failure. In these patients, they contribute to the disease by reducing heart output (14).
The association between beta-blockers and depression is still unclear. Some studies report a higher incidence of depression. Others found no changes or improvement of depression symptoms. There is not enough evidence to support either one or the other posture. That’s why depression is often listed as a side effect we should keep in mind (15, 16).
Beta-blockers interfere with adrenaline and noradrenaline. But that’s only the start of it. Studies suggest that it also impairs the secretion of melatonin. This hormone is an integral part of the sleep-wake cycle.
Thus, patients taking beta-blockers may have recurrent awakenings and nightmares that contribute to poor sleep. However, studies show that it is possible to solve this issue by supplementing with melatonin (17).
Facilitation of hypoglycemia in diabetic patients
Beta-blockers do not cause hypoglycemia. However, they may facilitate hypoglycemia in diabetic patients. They mask the signs and symptoms of hypoglycemia. For instance, they improve tachycardia and tremulousness. These symptoms typically accompany hypoglycemia and alert patients. Thus, it is important to select patients and only use beta-blockers when they are stable (18).
It is the clinical name given to excess potassium in the blood. Hyperkalemia only appears in a very small proportion of patients. It is usually related to non-selective beta-blockers. Thus, beta-blockers should not be used as a first choice in patients with kidney problems or insulin insufficiency (19).
What are the most common side effects of beta-blockers?
The symptoms mentioned above are the most severe side effects, but not the most common. As you will see next, the most common side effects are not as severe. They are as follows:
It is the most common gastrointestinal side effect. In some cases, it can be accompanied by diarrhea or constipation. It depends widely on every individual patient.
Reduced moisture in skin and mucosa
Salivary gland secretion and other types of secretion in the body depend on adrenergic signals. By blocking adrenergic signals, beta-blockers reduce these secretions. This causes dry mouth and dry skin symptoms (20).
Both hands and feet may become cold as a result of alterations in the disposition of blood. In some cases, beta-blockers may trigger Raynaud’s phenomenon (21).
Weakness and dizziness
Beta-blockers interact with an important cell pump called Na-K ATPase. By inhibiting this pump, there is a reduction in the action potential of neurons. Then, patients start displaying symptoms such as muscle fatigue, weakness, and dizziness (22).
Swelling of the feet
In some patients, beta-blockers may trigger swelling of the hands and feet. This is called edema and may appear in the respiratory tract as well.
As a result of the retention of liquid, patients with swelling in hands and feet may also increase their weight.
As you could see above, each significant side effect of beta-blockers is associated with a given disease or health condition. But we can work around the side effects of beta-blockers.
The recommendation is to prescribe the drug in cases of lower risk of side effects.
It is also important to have a healthy diet and follow instructions carefully. This prevents using an incorrect dose of beta-blockers that may trigger unwanted effects.
Natural Alternatives To Beta-Blockers
Instead of using drugs such as propranolol or metoprolol to control blood pressure, we can rely on natural alternatives to beta-blockers. For example:
This is a critical element to maintain the equilibrium between intracellular and extracellular fluid. It has the opposite effect of sodium and helps to maintain blood pressure in check.
L-arginine is an amino acid. It helps to produce nitric oxide (NO), which can cause blood vessels to enlarge and may help lower blood pressure.
Coenzyme Q10 is a naturally occurring chemical that exists in the human body. A review of studies in the Journal of Human Hypertension suggested that CoQ10 may help lower systolic blood pressure.
This is an essential mineral that plays many crucial roles in the body, such as supporting muscle and nerve function and energy production. Studies have also shown that low magnesium levels may lead to high blood pressure. As a result, it may also help to lower stress and anxiety levels.
Barberry is a traditional herb used to treat inflammatory and cardiovascular conditions. Studies show it can reduce blood pressure levels by lowering inflammatory markers.
It is a Chinese herb that improves the normal rhythm of the heart and has a positive effect on blood pressure. It may be useful to control heart failure, too (24).
Red yeast rice
A herbal supplement that contains natural statins. It maintains cholesterol levels within normal limits and it is useful to reduce cardiovascular risk (25).
You can also try low-budget alternatives to beta-blockers. They are mostly based on fresh foods, such as antioxidant foods, garlic, and much more:
- Antioxidant foods: They contribute to cases of hypertension in reducing oxidative stress. By doing so, antioxidant foods slow down the progression of atherosclerotic plaques in the blood vessels.
- Garlic: It is a natural solution to hypertension. Garlic is useful in heart disease and reduces cardiovascular risk.
- Krill oil: It contributes to our cardiovascular health by improving brain function. And krill oil also reduces our circulating levels of cholesterol and triglycerides.
Yet another way to reduce the incidence of side effects is to rely on the natural alternatives of beta-blockers.
Adrenaline releases in stressful conditions, especially now that we live in a stressful world. Thus, if we want to search for alternatives to beta-blockers, the first place to look for is inside each one of us.
If there is no biological problem with our body (such as phaeochromocytoma or hyperthyroidism), we can rely on relaxation techniques, breathing, and yoga to naturally reduce adrenaline secretion.
Meditation is one of the most important holistic practices. It is recommended for performance anxiety. Further, it also promotes muscle relaxation and to reduce the impact of stress (23).
Other alternatives include:
- Cognitive-behavioral therapy
- Systematic desensitization in cases of phobia or severe anxiety.
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As noted, the beta-blockers act by antagonizing beta-receptors regardless of any pathologic factors. Natural and holistic solutions improve blood pressure and reduce cardiovascular risk by other means.
These do not exactly mimic the action of beta-blockers. Therefore, it is essential to ask your doctor about the medications you’re taking and the new elements you’re planning to include in your diet.