Atenolol dosage, forms, and strengths

Atenolol is a generic prescription drug (brand name: Tenormin) that is FDA approved to treat hypertension, acute myocardial infarction (heart attack), and chronic stable angina (chest pain). It is also prescribed for off-label uses including rapid heartbeats, alcohol withdrawal syndrome, thyrotoxicosis (thyroid storm) prevention of cardiovascular events, and prevention of migraine. 

Atenolol is a generic version of the brand-name drug Tenormin. Atenolol is classified as a beta blocker. It is more generally categorized as an antianginal agent and an antihypertensive agent. It works by binding to receptors on the heart and blood vessels. It lowers blood pressure and heart rate while improving blood flow to the heart.

Atenolol is normally taken as a tablet. Dosing will depend on the condition being treated, the age of the patient, and how well their kidney functions.

RELATED: Free atenolol coupons | What is atenolol?

Atenolol forms and strengths

Atenolol is available as an immediate-release tablet and as a solution for intravenous infusion. It is available in the following strengths:

• Tablets: 25 mg, 50 mg, 100 mg

• IV infusion: 5 mg/10 mL

RELATED: Cardiac arrest vs. heart attack

Atenolol dosage for myocardial infarction 

Atenolol is given intravenously as soon as possible in patients who arrive at the hospital within 12 hours of myocardial infarction (heart attack). Atenolol reduces the strain on the heart by decreasing blood pressure, heart rate, and the strength of heart contractions. This reduces the risk for patients going into ventricular fibrillation (a life-threatening arrhythmia) or developing a second infarction. The dose is 5 mg administered over the course of minutes. The same dose is repeated 10 minutes later. Patients will receive a 50 mg oral dose 12 hours later, and continue taking 100 mg daily (either as a single dose or divided into two 50 mg doses) for six to nine days.

Atenolol dosage for angina pectoris

Atenolol is a first-line therapy for controlling symptoms in patients with chronic stable angina. Symptoms such as chest pain occur when the heart muscles are overly strained. Atenolol reduces strain on the heart by decreasing the rate and the force of heart muscle contractions. A healthcare professional will adjust the dose of atenolol in order to achieve a resting heart rate of 55 to 60 beats per minute and to achieve control of symptoms, with a maximum dose of 200 mg per day.

RELATED: What’s a normal heart rate?

Atenolol dosage for irregular heartbeat

Atenolol is used to control heart rate in patients with arrhythmia, most commonly atrial fibrillation (AF). It is useful for maintaining normal heart rhythm in patients who have had an arrhythmia and to reduce symptoms in patients experiencing an arrhythmia. The usual dose is 50-100 mg daily, with many patients starting out at 25 mg daily.

Atenolol dosage for hypertension

Atenolol is typically reserved as an add-on therapy for hypertension in patients whose symptoms are not adequately controlled by a combination of other medications such as calcium channel blockers, ACE inhibitors, and diuretics. It is not recommended to use atenolol as the first agent to treat hypertension since beta blockers give less protection against stroke and all-cause mortality compared to other antihypertensive medications. The dose of atenolol is adjusted to achieve a blood pressure of less than 130/80 mm Hg in most patients, with a maximum dose of 100 mg per day.

Studies have investigated which doses of atenolol are equivalent to metoprolol and propranolol dose ranges, in terms of effectiveness for blood pressure control. While the results do not demonstrate a direct relationship, they still can be useful for estimating an initial dose when changing between beta blockers. The results are summarized below:

Atenolol dosage for congenital long QT syndrome

Congenital long QT syndrome is a disease that is inherited at birth. It is characterized by an abnormality in heart conduction, and it puts patients at an increased risk for dangerous heart arrhythmias. Atenolol can benefit these patients by reducing the risk of heart arrhythmias. It may also help normalize heart conduction. The dosage range is 25-100 mg once or twice daily.

Atenolol dosage for migraine prevention

Atenolol prevents blood vessels in the brain from dilating—this widening of cerebral blood vessels is associated with migraines. Additionally, atenolol decreases certain neural activities that lead to migraines, while promoting neural conditions that alleviate migraines. It is taken orally once a day, starting with a low dose such as 25 to 50 mg, then increased if needed. The maximum daily dose for migraine prevention is 200 mg daily.

Atenolol dosage for thyrotoxicosis

Beta blockers such as atenolol are used when thyroid levels (specifically T3) become too high. High T3 levels cause an increase in beta-adrenergic activity, which can result in palpitations, fast heart rate, anxiety, and tremors. Atenolol reduces these symptoms by decreasing beta-adrenergic activity. Atenolol may also help lower T3 levels. The dose range for treating thyroid storms is 25-100 mg once or twice daily.

Atenolol dosage for children

Atenolol is not FDA approved for use in patients younger than 18 years of age but is commonly used off-label in pediatric patients. When used in the pediatric population, the dosage is based upon weight. Below are some common uses for atenolol in children, with the respective dose:

Atenolol dosage restrictions

Renally impaired patients

Patients with impaired kidney function require a lower dosage of atenolol. Refer to the following maximum doses of atenolol for renal impairment:

• Mild to moderate kidney disease

  (creatinine clearance between 15 and 35 mL/in/1.73m2): Maximum dose of 50 mg per day

• Severe kidney impairment

  (creatinine clearance less than 15 mL/in/1.73m2): Maximum dose of 25 mg per day

Contraindications

There are a few absolute contraindications to using atenolol. Do not take atenolol if you have:

• Severe bradycardia (slow heart rate)

• Sick sinus syndrome

• Second or third-degree heart block (in patients without a pacemaker)

• Severe or uncontrolled asthma

• COPD with a reactive component

• Cardiogenic shock

Atenolol is generally avoided in patients with acute heart failure (left ventricular dysfunction with volume overload), peripheral vascular disease, and mild to moderate asthma or COPD. A doctor will make an assessment if it can be used in these situations.

Do not use atenolol if you had an allergic reaction to atenolol or any other beta blocker medications such as metoprolol, labetalol, acebutolol, carvedilol, propranolol, bisoprolol, nadolol, or nebivolol.

Pregnancy and breastfeeding

It is not safe to take atenolol during pregnancy, as it could cause harm to the unborn child. In some situations, the risks of causing harm to the child must be weighed with the benefit to the mother, as in the case where atenolol is used to treat a life-threatening condition such as a heart attack. The risk for causing harm is greatest during the second and third trimester. 

Taking atenolol while breastfeeding exposes the infant to the drug’s effects. Atenolol becomes concentrated in breast milk, putting the infant at greater risk for dangerous side effects.

Atenolol effects on blood sugar

Patients who are diabetic should be aware that beta blockers such as atenolol can hide symptoms of low blood sugar, such as heart palpitations, tremors, and fast heart rate. One symptom of hypoglycemia that beta blockers do not hide is sweating. Beta blockers such as atenolol are also associated with impaired glucose tolerance and an increased risk of new onset diabetes, an important consideration for those with existing diabetes and those who are at risk for developing diabetes. It is important for diabetic patients to monitor blood sugar throughout the day, especially when taking a beta blocker.

Atenolol dosage for pets

Atenolol is commonly prescribed by veterinarians to treat coronary disease in pets. Most commonly, it is used to treat cardiomyopathy (usually caused by hyperthyroidism), heart arrhythmia, and hypertension in cats and dogs. This is an off-label use of atenolol since it is not FDA approved for use in animals.

The typical dose for dogs is 0.12-0.45 mg/lb once or twice daily. The typical dose for cats is 1 mg/lb.

How to take atenolol

• It is best to take this medicine on an empty stomach.

• Take atenolol as directed by your healthcare provider. Your dose may need to be changed several times to find what works best for you.

• Store the medicine in a closed container at room temperature (between 68 and 77 degrees Fahrenheit), away from heat, moisture, and direct light.

• Tell your doctor right away if you notice signs of serious side effects, such as cold hands and feet, or unusual drowsiness, weakness, or tiredness.

Atenolol dosage FAQs

How long does it take atenolol to work?

Atenolol can have an effect within one hour of taking a tablet by mouth. The maximum effect of a particular dose typically occurs two to four hours after taking an oral dose. This is when the concentration of atenolol is greatest in the bloodstream. 

When administered intravenously, atenolol has an effect within five minutes. 

For some conditions, such as hypertension, improvement is not directly related to the levels of atenolol in the bloodstream. For example, it can take three to 14 days for atenolol to have its full effect as a treatment for hypertension. It can take three to six hours for atenolol to have its full effect in treating angina.

How long does atenolol stay in your system?

For most adults, atenolol will be eliminated from the body 32 hours after the last dose. The amount of time it takes to eliminate atenolol will be much longer in older adults and patients with impaired kidney function.

What happens if I miss a dose of atenolol?

If you miss a dose of atenolol, take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

How do I stop taking atenolol?

Atenolol should never be stopped abruptly. It must be tapered gradually to prevent withdrawal symptoms such as chest pain, increased blood pressure, and elevated heart rate. Abrupt discontinuation has resulted in heart arrhythmias and heart attacks in some patients. To prevent these risks, the dose of atenolol should be gradually decreased over the course of one to three weeks before stopping altogether. Patients should minimize physical activity during this period. If symptoms such as chest pain occur after stopping atenolol, the medication should be temporarily reintroduced.

What is the maximum dosage for atenolol?

The maximum dosage of atenolol depends on patient-specific factors such as age, kidney function, and underlying heart disease. Generally, the max daily dose is 200 mg per day for adults and 4 mg/kg/day in children.

What interacts with atenolol?

Fruit juices such as grapefruit, orange, and apple juice can decrease the absorption of certain beta blockers, so it is best to avoid drinking these while taking atenolol. Taking atenolol with any other food can have a similar effect, so ideally atenolol should be taken on an empty stomach. The effect of food is less prominent than fruit juice, however, and not likely to have clinical consequences. Atenolol may be taken with or without food, but patients should be consistent in either case.

Bronchodilators

Other medications can interact with atenolol. Bronchodilators such as albuterol, vilanterol, and formoterol (used for shortness of breath in patients with COPD and asthma) can have the opposite effect of beta blockers, potentially resulting in adverse cardiac side-effects. Atenolol can also reduce the efficacy of bronchodilators, resulting in bronchospasms or trouble breathing. The interaction between bronchodilators and beta blockers is greater for non-cardioselective beta blockers, compared with cardioselective beta blockers such as atenolol. While these interactions have been observed, it is still considered safe to take atenolol with bronchodilators.

Centrally acting alpha-agonists

Centrally acting alpha-agonists (such as guanfacine, methyldopa, and clonidine) can cause hypotension when taken with atenolol. Additionally, there is a greater risk for rebound hypertension when a centrally acting alpha-agonist is used concomitantly with atenolol, and either medication is stopped abruptly.

Other drugs that lower blood pressure

Other classes of drugs that lower blood pressure can increase the risk of developing low blood pressure when taken with atenolol. This includes calcium-channel blockers (such as verapamil, amlodipine, diltiazem), although prescribers may use these with atenolol under careful supervision.

Arrhythmia drugs

Drugs that affect the heart rhythm (such as digoxin, amiodarone, dofetilide, and disopyramide) may slow down the heart too much when taken with atenolol. Close supervision by a prescriber is necessary when atenolol is used with arrhythmia drugs.

NSAIDs

NSAIDs such as diflunisal, ibuprofen, indomethacin, and naproxen can offset the blood pressure lowering effects of atenolol by causing increased potassium levels and fluid retention.

MAOIs

A class of mental health drugs called monoamine oxidase inhibitors MAOIs can increase the blood pressure-lowering effects of atenolol. These include isocarboxazid, selegiline, rasagiline, phenelzine, and tranylcypromine). MAOIs continue to increase the blood pressure-lowering effects of atenolol for up to 14 days after they are stopped.

Resources

• Tenormin (atenolol)

• Atenolol dosing

• Atenolol

• Beta blockers and beta agonists: What is the risk?

• Atenolol

• Juice interactions: What patients need to know

• Effectiveness and safety of concurrent beta blockers and inhaled bronchodilators in COPD with cardiovascular comorbidities

• Adverse respiratory effect of acute β-blocker exposure in asthma