About
Atenolol
(uh-ten-uh-lawl)
Atenolol (Sold in the US as Tenormin) A medication that blocks the action of a portion of the involuntary nervous system that stimulates the pace of the heartbeat. By blocking the action of these nerves, atenolol reduces the heart rate and is useful in treating abnormally rapid heart rhythms. Atenolol also reduces the force of heart muscle contraction, lowers blood pressure, and is helpful in treating angina. It is also used for the prevention of migraine headaches and the treatment of certain types of tremors. The brand name is Tenormin. Generic is available.
What is Atenolol Used For?
Atenolol (trade name Tenormin) can be used to treat cardiovascular diseases and conditions such as hypertension, coronary heart disease, arrhythmias, angina (chest pain) and to treat and reduce the risk of heart complications following myocardial infarction (heart attack)
Due to its hydrophilic properties, the drug is less suitable in migraine prophylaxis compared to propranolol, because for this indication, atenolol would have to reach the brain in high concentrations, which is not the case (see below).
Atenolol is a so-called β1-selective (or ‘cardioselective’) drug. That means that it exerts greater blocking activity on myocardial β1-receptors than on β2 ones in the lung. The β2 receptors are responsible to keep the bronchial system open. If these receptors are blocked, bronchospasm with serious lack of oxygen in the body can result. However, due to its cardioselective properties, the risk of bronchospastic reactions if using atenolol is reduced compared to nonselective drugs as propranolol. Nonetheless, this reaction may also be encountered with atenolol, particularly with high doses. Extreme caution should be exerted if atenolol is given to asthma patients, who are particularly at risk; the dose should be as low as possible. If an asthma attack occurs, the inhalation of a β2-mimetic antiasthmatic, such as hexoprenaline or salbutamol, will usually suppress the symptoms.
Provisional data suggests that antihypertensive therapy with atenolol provides weaker protective action against cardiovascular complications (e.g. myocardial infarction and stroke) compared to other antihypertensive drugs. In particular, diuretics are superior. However, controlled studies are lacking.[4]
Unlike most other commonly-used β-blockers, atenolol is excreted almost exclusively by the kidneys. This makes it attractive for use in individuals with end-stage liver disease.
What Side Effects Can Be Caused From Using Atenolol?
Atenolol causes significantly fewer central nervous system side effects (depressions, nightmares) and fewer bronchospastic reactions, both due to its particular pharmacologic profile.
It was the main β-blocker identified as carrying a higher risk of provoking type 2 diabetes, leading to its downgrading in the United Kingdom in June 2006 to fourth-line agent in the management of hypertension.[3]
In addition, β-blockers blunt the usual sympathetic nervous system response to hypoglycemia (i.e. sweating, agitation, tachycardia). These drugs therefore have an ability to mask a dangerously low blood sugar, which further decreases their safety and utility in diabetic patients.
Side effects include:
* indigestion, constipation
* dry mouth
* fatigue or dizziness (especially cases of orthostatic hypotension)
* hair loss
* problems with sexual function
* runny/blocked nose
* depression and confusion
* difficulty sleeping, nightmares
* weakness or lack of energy
These side effects may or may not be experienced, but if they are, you should notify your doctor.
More serious side effects can include:
* hallucinations
* low blood pressure (hypotension)
* skin reactions, eg. rash, hives, flaking of skin, worsening of psoriasis
* sensation of ‘pins and needles’ hands or feet
* irritated eyes, visual disturbances
* difficulty hearing
* difficulty speaking
* unsteadiness when walking
These side effects can be serious and may indicate urgent medical attention is necessary. All of these side effects are very rare, and others not mentioned in the above list can occur in some people.
Dosage
In patients with normal renal function, the daily dose is 25 to 50 mg for the management of hypertension depending on the indication and severity of the disease. In most patients, the physician will start with a low initial dose and make increments in weekly intervals as tolerated. Dosage can vary from as little as 25 mg to 200mg a day. In cases of doses over 100mg, the dosage is usually divided and taken twice daily.
For the management of angina, 100mg daily may be given.
In patients with impaired renal function the daily dose should be reduced according to the clinical response of the individual patient. If a patient with end-stage renal failure is scheduled on regular dialysis, usually 50 mg are given after each dialysis procedure. In these patients, a severe hypotension may occur afterwards.
Overdose
Symptoms of overdose are due to excessive pharmacodynamic actions on β1 and also β2-receptors. These include bradycardia, severe hypotension with shock, acute heart failure, hypoglycemia and bronchospastic reactions. Treatment is largely symptomatic. Hospitalization and intensive monitoring is indicated. In early cases emesis can be induced. Activated charcoal is useful to absorb the drug. Atropine will counteract bradycardia, glucagon helps with hypoglycemia, dobutamine can be given against hypotension and the inhalation of a β2-mimetic as hexoprenalin or salbutamol will terminate bronchospasms.
