Beta Blockers

Beta-blockers reduce the heart rate, heart’s workload and the heart’s output of blood, which in turn lowers blood pressure.

Beta-blockers, also written as β-blocker, also called beta- adrenergic receptor blocking agents, it binds to beta receptors present on the cells of the heart, arteries, kidneys and other tissues stimulated by the stress hormones such as adrenaline and noradrenaline.

Some compelling indication for the use of beta-blockers in hypertensive patients are childbearing women, increased sympathetic drive, and intolerance to ACE inhibitors & ARBs.

Guidelines for the hypertension management in the UK were updated; beta-blockers are not recommended as the first-line drug in hypertension patients without compelling indications.

Mechanisms of Action - Initially these drugs decreases cardiac output, followed by reduction in peripheral vascular resistance. Other actions include decrease in plasma renin activity, resetting of baroreceptors, release of vasodilator prostaglandins, and blockade of beta-receptors.

Commonly prescribed non-selective beta-blockers medications on the market, include:

1. Carteolol hydrochloride (brand name: Cartrol)
2. Nadolol (brand name: Corgard)
3. Penbutolol Sulfate (brand name: Levatol)
4. Propranolol hydrochloride (brand name: Inderal)
5. Sotalol hydrochloride (brand name: Betapace)
6. Timolol maleate (brand name: Blocadren)
7. Pindolol (brand name: Visken)
8. Carvedilol (brand name: Coreg)
9. Labetalol hydrochloride (brand name: Trandate)
10. Oxprenolol Hydrochloride (brand names: Trasacor, Trasicor, Coretal, Laracor, Slow-Pren, Captol, Corbeton, Slow-Trasicor, Tevacor, Trasitensin, Trasidex)

Commonly prescribed cardioselective beta blockers medications on the market, include:

1. Betaxolol (brand name: Kerlone)
2. Acebutolol (brand name: Sectral)
3. Atenolol (brand name: Tenormin)
4. Metoprolol succinate (brand name: Toprol-XL, Metoprolol Succinate ER)
5. Metoprolol tartrate (brand name: Lopressor, Metoprolol Tartrate)
6. Bisoprolol fumarate (brand name: Zebeta)
7. Nebivolol (brand name: Bystolic)
8. Esmolol (brand name: Brevibloc)

Beta blockers are preferred treatment in hypertension with angina, resting tachycardia (racing heartbeat while resting), a rapid onset heart attack and atrial fibrillation. Less commonly prescribed for a migraine headache, tremor, and anxiety.

The sympathetic nervous system is part of the autonomic nervous system. It mediates the fight-or-flight response stimulated by the stress hormones such as adrenaline and noradrenaline. It is responsible for raising alertness, heart rate, and blood pressure. Beta blockers blunt this exaggerated physiological response to stress, which in turn reduces high blood pressure.

There are three types of beta receptors control several functions based on their location. Beta 1 receptors are present in the heart, eye, and kidneys. Beta 2 receptors are present in the lungs, gastrointestinal tract, liver, uterus, blood vessels, and skeletal muscle. Beta 3 receptors are present in fat cells.

Some beta-blockers are selective to the beta 1 receptor more than the beta 2 receptor called cardioselective agents. Nonselective beta blockers can bind to both the beta 1 and beta 2 receptors.

Can I use beta blocker, I have hypertension and hyperthyroidism

Hyperthyroidism is associated with an increased beta-adrenergic receptors.  This increased beta-adrenergic activity is responsible for many of these symptoms of hyperthyroidism that include palpitations, tachycardia, nervous, anxiety, and heat intolerance. It explains the ability of beta blockers to improve rapidly many of these symptoms.

Is it true, beta-blocker can mask low blood sugar symptoms in diabetes patients?

Yes, beta blockers may mask low blood sugar symptoms specifically rapid heartbeat in people with diabetes who treated with insulin. So you cannot rely on the symptoms to know your blood sugar is low, and it can be dangerous.

I have diabetes, is it ok for me to use beta-blockers?

Beta-blockers have been implicated in causing or worsening diabetes control. Studies show the risk of the onset of diabetes in people who took beta-blockers was approximately 20 to 28% greater than those who did not take beta-blockers.

Beta-blockers may inhibit the glucose release from the liver, block insulin secretion from the pancreas, and thus lower insulin levels even during high blood glucose.

There is evidence that not all beta-blockers affect insulin secretion. For example, cardioselective beta blockers have an affinity for the beta-1 receptor; these drugs are less likely to interfere with the secretion and regulation of insulin.

Do beta blockers help with anxiety, social interactions, etc.?

Social anxiety disorder, also known as social phobia, involves intense fear of social situations because of your feeling of being watched or evaluated by others.

Common social anxiety triggers are meeting new people, public speaking, stage performance, being the center of attention, talking with important people, eating or drinking in public, making phone calls, and attending parties.

When a person is under stress, stress hormones bind to various receptors that create physical symptoms of anxiety like palpitations, sweating, and muscle tension. Beta blockers are useful for relieving anxiety and social phobia. Beta blockers function by preventing stress hormones binding to the receptors, thereby it will not affect the emotional symptoms of anxiety and only control physical symptoms such as shaking hands/voice, sweating, and rapid heartbeat.

Can patients with COPD or asthma take a beta-blocker?

Beta 2 adrenergic receptors are present in the bronchi of the lungs. During stress, epinephrine act on these receptors causes the bronchi to relax, which in turn opens the airways. It helps you breathe well and oxygenate better to carry of flight or fight activity.

Asthma involves constriction of the airways. Salbutamol is the puffer medication used to treat an asthma attack that opens up the airways by acting on beta 2 adrenergic receptors.

So a person with asthma do not want to take a beta blocker because it is a medication that prevents your airways from opening, thus complicates your chronic obstructive pulmonary disease (COPD) or asthma treatment.

Is there a condition that might stop prescribing beta blocker?

For some conditions beta blockers are not recommended, this includes uncontrolled heart failure, low blood pressure, heart rhythm problems, or bradycardia (slow heart beat). If you have asthma or another lung disease, beta blockers are not advisable because they may provoke severe asthma attacks.

However, cardioselective beta blockers have an affinity for the beta-1 receptor result in fewer adverse effects on your lungs. It selectively blocks beta-1 receptors with little or no effect on beta-2 receptors.

Does beta-blocker affect sexual function (erectile dysfunction) in normal males?

For proper erection, activation of beta-receptors in the tissues and arteries of the penis required. Some (non-selective) beta-blocker bind to every beta-receptors and block it and does not allow the blood vessel to relax and allow the penis to fill up with blood to make a proper erection. Some beta blockers such as carvedilol and labetalol also block certain alpha receptors, which can cause ED.

However, 'cardio-selective' beta blockers are those that only block the beta-1 receptors and do not tend to cause erectile dysfunction. Nebivolol is a beta blocker that helps erectile function by increasing nitric oxide (NO) with their alpha-blocking properties.

Do not stop beta blocker on you own or abruptly; it can lead to angina, hypertension, or heart attack.

Additionally, use it with caution in the elderly, pregnant women, renal disease, and thyroid disease. Do not use it, if you have asthma or lung disease.

Who should avoid Beta-Blockers?

If you have slow heart rate, heart block/shock, pregnant or nursing women, kidney or liver problems, asthma, diabetes, overactive thyroid, and elderly should discuss with the doctor, regarding any specific risks of using Beta-Blockers.

What are the side effects of Beta-Blockers?

Constipation, diarrhea, gastrointestinal problems, asthma symptoms, bronchial spasm (especially in asthmatics and COPD patients), Bradycardia, tiredness, and decreased ability to exercise. A headache, depression, anxiety, slow heartbeat, rash, cold hands & feet (due to reduced blood flow to the limbs), lightheaded, dizziness, insomnia, strange dreams, and impotence.

Metabolic effects (raise triglyerides levels and decrease HDL cholesterol; may worsen insulin sensitivity and cause glucose intolerance). Increased incidence of diabetes mellitus.

If you have diabetes and on insulin therapy, then you should closely monitor your response to insulin therapy.

If you are planning to become pregnancy, then before conception consult your doctor for a safer hypertension medication.

What are the warning signs of beta-blockers?

Consult a doctor immediately if you are having chest pain, breathing problems, slow/irregular heartbeat, swelling of the hands, feet, or legs.