Beta blocker
Beta-blockers are medicines that work by temporarily stopping or reducing the body's natural 'fight-or-flight' responses.
In turn, they reduce stress on certain parts of the body, such as the heart and the blood vessels in the brain. They lower blood pressure, protect against heart attacks, and can improve the outlook for people with heart failure.
They are prescribed for several different conditions including high blood pressure, angina, some abnormal heart rhythms, heart, anxiety, migraine, glaucoma, and overactive thyroid symptoms.
They are also sometimes known as beta antagonists, beta-adrenergic blocking agents, or beta-adrenergic antagonists.
Pharmacologist James Black won the Nobel Prize in Physiology and Medicine for his development in 1964 of the first receptor-blocking drug, propranolol, which is still in use today.
Fast facts about beta-blockers
Beta-blockers are prescribed in conditions where the heart rate needs to be slowed.
Doctors commonly recommend beta-blockers for patients with irregular heartbeats, angina, and high blood pressure.
Beta-blockers also offer relief for glaucoma, overactive thyroid, and anxiety.
There are many different brands of beta-blocker.
Taking beta-blockers can cause dizziness, cold hands and feet, weight gain, and fatigue.
Function
Beta-blockers
Beta-blockers slow the heart beat to treat conditions in which the heart is under stress.
Beta-blockers block the hormones adrenaline and noradrenaline in the sympathetic nervous system.
The sympathetic nervous system is part of the autonomic nervous system. It activates the 'fight-or-flight' response.
Adrenaline and noradrenaline prepare the muscles in the body for exertion. This is a crucial part of responding to danger.
Overexposure to these hormones can be harmful. Too much adrenaline can lead to rapid heartbeat, high blood pressure, excessive sweating, anxiety, and palpitations.
Blocking the release of these hormones blockers decreases the oxygen demands and reduces stress on the heart.
This lowers the force of the contractions of the heart muscles, and of blood vessels in the heart, the brain, and the rest of the body.
Beta-blockers also obstruct the production of angiotensin II, a hormone produced by the kidneys.
Reducing the amount of angiotensin relaxes and widens the blood vessels, easing the flow of blood through the vessels.
Beta-blockers are used to treat the following:
Angina, or chest pain
Heart failure
Hypertension, or high blood pressure
Atrial fibrillation, or irregular heartbeat
Myocardial infarction, or heart attack
Uses
Beta-blockers anxiety
Beta-blockers can help to relieve the 'fight-or-flight' reactions that fuel anxiety.
Less commonly, they may be used for migraines, glaucoma, overactive thyroid, tremors, and anxiety.
Glaucoma
The high pressure within the eyeball is reduced using beta-blocker eye drops. The medication lowers the production of fluid inside the eyeball.
Anxiety
Beta-blockers block the effects of stress hormones. As a result, they can also reduce the physical symptoms of anxiety such as trembling and sweating.
A person experiencing persistent anxiety, however, may also need additional treatment, such as counseling.
Hyperactive thyroid and tremor
Beta-blockers can reduce symptoms such as tremor and slow the heart rate of patients with an overactive thyroid.
Types and brands
Beta-blockers can be selective or non-selective. Selective beta-blockers mostly affect the heart, while non-selective ones affect other parts of the body.
Here are some common types and brands of beta-blockers:
acebutolol (Sectral, brand discontinued)
atenolol (Tenormin)
betaxolol (Kerlone, brand discontinued)
bisoprolol (Cardicor, Emcor, Zebeta all brands discontinued)
metoprolol (Lopressor, Toprol XL)
nadolol (Corgard)
propranolol (Inderal LA, Inderal XL, Hemangeol, InnoPran XL)
timolol ophthalmic solution (Betimol, Istalol, Timoptic)
Side effects
The most common side effects of beta-blockers are:
cold feet and hands
fatigue
nausea, weakness, and dizziness
dry mouth, skin, and eyes
slow heartbeat
swelling of the hands and feet
weight gain
The following less common side effects are also possible:
sleeping difficulties and disturbances
erectile dysfunction
abdominal cramps
constipation
diarrhea
depression, memory loss, or confusion
back or joint pain
Patients who feel dizzy or fatigued should not drive.
Cautions
Beta-blockers asthma
People with asthma should advise their doctor before taking beta-blockers.
People should advise their doctor if they have a history of the following before taking beta-blockers:
asthma
bronchospasm
severe peripheral arterial disease, including Raynaud's syndrome
slow heart rate
uncontrolled heart failure
Beta-blockers can be taken by those with stable heart failure.
Patients with diabetes, especially hypoglycemia, or low blood sugar, should monitor their blood sugar regularly, as beta-blockers can obstruct signs of low blood sugar, such as rapid heart beat.
Some types of beta-blockers may be used during pregnancy if advised by a doctor.
Interactions
Beta-blockers, like all drugs, can interact with a number of other medications.
As long ago as 1995, it was found that beta-blockers could interact with a range of common medications.
These include:
Anti-hypertensives
Anti-anginal drugs
Anti-arrhythmics
Non-steroidal anti-inflammatory drugs (NSAIDs)
Anti-ulcer medications
Anesthetics
Warfarin
HMG-CoA reductase inhibitors
Different beta-blockers can have different interactions.
A pharmacist or doctor will be able to provide a comprehensive and up-to-date list of beta-blocker interactions.
Always advise your treating doctor of any other courses of medication currently being followed.
Stopping a course of beta-blockers
Patients must not suddenly stop taking beta-blockers without their doctor's advice and close supervision.
Suddenly ceasing beta-blocker treatment may worsen the patient's condition, especially after a heart attack, or during the treatment of angina.