Beta Blockers

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What Are Beta Blockers?

Beta blockers are a group of prescription drugs that are antagonists (a substance that blocks the normal functioning of the receptor) of the β1 and β2 receptors, thereby inhibiting the activity of the sympathetic nervous system.

Drugs belonging to this group are among the most frequently used in cardiology, including in the treatment of hypertension. They have a cardioprotective effect (proven effectiveness in preventing myocardial infarction).

Beta Blockers: What Are, Mechanism of Action

β-adrenergic Receptors

β-adrenergic receptorsTrusted Source are specific locations on the surface of the body's cells to which catecholamines. The attachment of these active substances to the receptor produces an array of effects, depending on the type of β-adrenergic receptor and its location in the body.

In the heart, β1 receptorsTrusted Source increase the frequency of rhythm and force of contraction and accelerate the conduction of electrical impulses. In the salivary glands, they increase the production of saliva containing amylase. In the kidneys, they increase the secretion of the renin enzyme in the periglomerular apparatus. In adipose tissue, they increase lipolysis – which leads to fat breakdown.

β2 receptorsTrusted Source are present in the musculature of blood vessels, the digestive tract, the urogenital system, and the respiratory system. Their activation causes relaxation in these systems. β2 receptors are also present in the eye, where they increase the production of aqueous humor, and in the pancreas, where they increase insulin secretion.

β3 receptorsTrusted Source are in adipose tissue and skeletal muscles. When activated, they increase lipolysis in adipose tissue and induce thermogenesis in skeletal muscles. This leads to heat production.

In conclusion, the β-adrenergic receptors have different effects depending on their kind and place in the organism. Understanding the distribution and activation of these receptors is critical for designing targeted treatments for diverse conditions.

Types

There are numerous various kinds of beta blockersTrusted Source. Their standard division refers to the selectivity of beta-adrenergic receptor blockade:

Medications from the beta blocker group can also be divided into those with intrinsic sympathomimetic activity and those that can stabilize cell membranes. In addition, beta blockers can be divided based on the generationTrusted Source of the drug:

Mechanism of Action

Our organism uses the cell signaling system to regulate particular operations and functions. It uses specific locations on the surface of cells, called receptors, where certain chemicals can attach neurotransmitters. If a chemical with the correct structure attaches to a receptor, it activates the cell to answer in a specific manner. The way a cell reacts depends on where it is located and what is its function. If the body needs specific cells to function, it can produce more of the chemical, activating the cells' receptors.

Many drugs work by artificially influencing this process, but they can do it in two ways. In the first method, the drug attaches and activates the receptor sites. In this way, cells that would otherwise not be active can be stimulated. The drug attaches to the receptors in the second method but does nothing else. It causes the receptor to be blocked by other chemicals (beta blockers reduce the number of receptors available for activation, which slows down cell activity).

Those drugs exhibit various effects that vary depending on their anatomical site of action. In the heart, these agents diminish heart rate, reduce cardiac muscle contractility, and decrease atrioventricular conduction. They also lower cardiac output, enhance blood flow through coronary vessels, and decrease oxygen consumption by the heart. Moreover, beta blockers reduce peripheral resistance and promote blood vessel relaxation. The mix of those actions lowers blood pressure. Additionally, these agents have been found to reduce smooth muscle contraction in the eye, decreasing intraocular pressure.

Indications

Beta blockers are a class of drugs for various medical conditions. Primarily, they are used selectively on β1 receptors to treat cardiological conditionsTrusted Source. However, non-selective drugs are also prescribed, albeit less frequently. Beta blockers belonging to this group are generally used to treat anxiety disorders and essential tremors and as a preventive measure against migraines.

Ischemic heart disease and heart failure are the most common indications for the use of those medications. Beta blockers are known to reduce myocardial infarctions, which are the leading cause of death among people with ischemic heart disease.

Beta blockers can also be used during the management of glaucoma. This treatment aims to reduce intraocular pressure by decreasing the production of aqueous humor in the eye. Those medications are considered an effective and safe to combat glaucoma as they do not affect the pupil width or eye accommodation. They also have a long-lasting impact. You must only take them twice a day.

In conclusion, beta blockers have a broad range of indications for their use, ranging from cardiological conditions to open-angle glaucoma. While they are generally safe, their use requires careful monitoring, especially in patients with underlying conditions.

Contraindications

Absolute contraindicationsTrusted Source to the use of β-blockers include:

Relative contraindications are:

Individual drugs belonging to the group of β-blockers may differ in the scope of contraindications to use. Contraindications for a specific preparation can be found on the leaflet attached to the drug package.

Pregnancy

About the safety of beta blockers, it is significant to note that non-selective drugs should not be prescribed to pregnant womenTrusted Source. Nonselective beta blockers may cause a reduction in blood flow to both the uterus and placenta, which can lead to severe complications. Therefore, the choice of beta blocker is made carefully, considering the patient's medical history, including any pre-existing conditions and used medications.

Specialists need to select the appropriate beta blocker based on an individual patient's needs and medical history. For instance, in the case of pregnant women, avoid non-selective beta blockers, which can have adverse effects on fetal development and maternal health. The specialists decide to prescribe a beta blocker.

In summary, the use of beta blockers should be carefully considered, especially in pregnant women, to avoid any adverse effects on the health of both the mother and the fetus. The appropriate beta blocker selection should be based on individual patient needs, medical history, and consultation with a qualified healthcare professional.

Beta Blockers: What Are, Mechanism of Action

Alcohol

It is essential to be aware of the probable damaging consequences of combining beta blockers and alcoholTrusted Source, as both substances can lower blood pressure. This combination can rapidly decrease blood pressure, and the individual can experience lightheadedness, dizziness, weakness, and even fainting. The severity of these symptoms can vary depending on the prescribed dose of beta blockers and the amount of alcohol consumed.

Treatment

Beta blockers are used in various treatmentTrusted Source conditions. Below, you will find the most common disorders and how those drugs can help during them.

Angina Pectoris

Beta blockers are recommended, especially in people with reduced cardiac performance. They improve exercise tolerance and reduce the frequency of angina attacks. However, it should be remembered that beta blockers routinely used in the treatment of typical forms of ischemic heart disease (especially non-selective ones) are contraindicated because they may provoke coronary artery spasms.

Heart Failure

Beta blockers enhance individuals with heart failure induced by damaged left ventricular contraction. Specialists suggest that all patients with left ventricular dysfunction take beta blockers, regardless of the severity of symptoms, as part of a treatment program.

Cardiac Arrhythmias

In the case of irregular heart rhythm in people with atrial fibrillation, beta blockers are also used. They slow your heart rate, relieving the symptoms caused by atrial fibrillation, especially palpitations and fatigue.

Recurrent Heart Attacks

Beta blockers help decrease the gamble of further heart attacks. Specialists advise that all individuals who have had a heart attack should be prescribed beta blockers before release from the hospital as part of risk-reduction efforts. Treatment should usually be lifelong.

Glaucoma

Beta blockers are often prescribed in the form of eye drops when glaucoma occurs. Glaucoma is when the pressure in the eye rises. It happens due to fluid build-up. The beta blocker is designed to reduce this fluid production and pressure in the eye.

Anxiety

The properties of beta blockers also include blocking the action of stress hormones, which translates into a decrease in the physical manifestation of anxiety, such as tremors and sweating.

It is worth remembering, nevertheless, that we do not only use beta blockers during anxiety treatment. Therapy is based on a variety of methods, including psychotherapy, which can help address the underlying causes of anxiety.

Hyperthyroidism

Beta blockers reduce symptoms such as tremors and rapid heart rate in people with hyperthyroidism. It is due to blocking the action of thyroid hormone.

Side Effects

Although beta blockers are helpful. However, they may cause numerous side effectsTrusted Source, too. The most common include:

Other less common side effects include:

Beta Blockers: What Are, Mechanism of Action

Interactions With Other Drugs

Beta blockers may have interactions with other medicaments. The use of beta blockers together with calcium blockers or other antiarrhythmic drugs may enhance their cardio depressant effect; therefore, if necessary, patients must be closely monitored. Nonsteroidal anti-inflammatory drugs may reduce the antihypertensive effect of beta blockers.

In diabetic patients who use treatment, a beta blocker may intensify or prolong hypoglycemia because beta blockers will potentiate the action of insulin when the two drugs are administered simultaneously. In turn, the effect of antidiabetic drugs from the sulfonylurea group may be reversed by beta blockers.

As mentioned earlier, beta blockers may intensify and prolong the toxic effects of alcohol.

Other drugs include:

These are just some of the many interactions of beta blockersTrusted Source, the list is much longer, so you should always inform your doctor about all medications you take because improperly used beta blockers may do more harm than good.

Discontinuation of Beta Blockers

Sudden discontinuation of beta blockersTrusted Source is very dangerous for the patient because it leads to the occurrence of withdrawal syndrome, which manifests itself in tachycardia, increased blood pressure, muscle tremors, and excessive sweating. Therefore, if you want to stop taking medications, you should consult your doctor.

Administering them simultaneously with oral antidiabetic drugs increases their hypoglycemic effect, therefore, when taking beta blockers with these preparations, blood glucose levels should be constantly monitored.

Due to numerous interactions with food, they should always be taken simultaneously and at a strictly defined time after a meal.

Sources

April 27, 2024
10 minutes read
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