Atenolol: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on Dec 2, 2024.

1. How it works

• Atenolol is a medication that may be used to treat certain heart conditions.
• Atenolol works by blocking the effects of epinephrine on beta-1 receptors within the heart tissue, causing the heart to pump more slowly and with less force. This slows the heart rate.
• The exact way atenolol works to lower blood pressure is not known but studies have shown it decreases cardiac output, inhibits renin release from the kidneys, and reduces the activity of the sympathetic nervous system.
• Atenolol belongs to the class of drugs known as beta-blockers. It is called a selective beta-blocker because at low dosages it only works on beta1 receptors and has a low affinity for beta2 receptors located in the airways (breathing tubes).

2. Upsides

• Atenolol may be used in the treatment of high blood pressure (hypertension). Lowering blood pressure with medications such as atenolol has been shown to reduce the risk of a stroke or a heart attack (myocardial infarction).
• May be used long-term to manage the symptoms of chronic stable angina and to manage NSTE ACS (non-ST-segment-elevation acute coronary syndrome).
• When given to stable patients immediately following a heart attack, atenolol has been shown to reduce the risk of death.
• Has been used to treat supraventricular tachycardias (SVts) such as atrial flutter, junctional tachycardia, focal atrial tachycardia, or paroxysmal supraventricular tachycardia (PSVT).
• May be used off-label for other conditions.
• Atenolol may be used alone or in addition to other antihypertensives.
• Administered orally (by mouth).
• Only needs to be taken once a day.
• The usual starting dosage is 25-50 mg/day.
• Takes one to two weeks for the full hypotensive effect to be seen.
• No dosage adjustment is needed for liver disease.
• Atenolol has a selective action on beta1 receptors located in the heart; however, this selectivity is only apparent at low dosages. At higher dosages, atenolol may affect beta2 receptors in the airways, which may affect breathing.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Slow heartbeat, dizziness, fatigue, cold extremities, and heart failure are the most commonly reported side effects.
• Generally not recommended for people with bronchospastic disease; however, may be used in certain circumstances. Do not use in people with sinus bradycardia, AV block greater than first degree, cardiogenic shock, overt or decompensated heart failure, certain MI patients, untreated pheochromocytoma, or with hypersensitivity to atenolol.
• Can mask symptoms of hypoglycemia or hyperthyroidism, so should be used with caution in people with diabetes or thyroid disease.
• May aggravate peripheral circulatory disorders (conditions that cause reduced blood flow to the hands or feet).
• May cause several unwanted heart-related effects and may affect breathing, so the response must be monitored.
• May cause changes in liver enzymes, headache, hallucinations, and impotence.
• Cardioselectivity of atenolol is not absolute, and at dosages higher than 50mg/day atenolol is more likely to inhibit beta2 receptors, mostly located in the bronchial and vascular musculature. The lowest effective dose should be used to maintain cardioselectivity.
• The clearance of atenolol from the body may be delayed in people with renal disease. The dosage should be adjusted depending on the response. For patients with a CL_CR of 15-35 mL/minute per 1.73 m² the maximum is 50mg daily. For patients with a CL_CR < of 15 mL/minute per 1.73 m² the maximum is 25mg daily or 50mg every other day. For hemodialysis patients administer 25mg or 50mg after each dialysis. Monitor for marked reductions in BP.
• The dosage of atenolol needs to be individualized according to the patient's response. Monitor BP regularly during treatment and adjust the dosage as necessary. 25 mg/day is the usual starting dose for seniors.
• Needs to be tapered off over approximately 2 weeks if it has been taken long-term.
• May not be suitable for some people including those with heart failure, a significantly slow heartbeat, or reduced peripheral circulation.
• An injectable preparation is no longer commercially available in the United States.
• May interact with some medications including other medications used for the treatment of arrhythmias or angina.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Atenolol works on heart-specific receptors to lower blood pressure and slow heart rate; however, this selective effect on the heart may be lost with dosages greater than 50mg/day which increases the risk that atenolol may adversely affect breathing.

5. Tips

• May be taken with or without food.
• Should always be used as part of a comprehensive cardiovascular risk reduction program which includes diabetes management, smoking cessation, exercise, and other drug therapies. May be used in addition to other blood pressure-lowering medicines.
• Seek medical advice immediately if shortness of breath develops.
• Seek medical advice if any new numbness, pain, skin color changes, or reduced sensitivity occurs in fingers or toes.
• Sudden discontinuation has been associated with an exacerbation of angina, and sometimes myocardial infarction (heart attack) or ventricular arrhythmias. If you need to discontinue atenolol, your doctor will advise you how to do this slowly over at least a week.
• If you have diabetes, atenolol may mask some of the symptoms of hypoglycemia (low blood sugar).

6. Response and effectiveness

• Peak concentrations are reached within two to four hours of an oral dose of atenolol. Heart rate and blood pressure lowering effects persist for at least 24 hours following a single dose.

7. Interactions

Medicines that interact with atenolol may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with atenolol. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with atenolol include:

• alpha-blockers such as doxazosin or terazosin
• indigestion and heartburn medications, such as cimetidine and ranitidine
• insulin
• methylphenidate
• other medications including celecoxib, clonidine, hydralazine, and rifampicin
• NSAIDs, such as diclofenac, ibuprofen, and indomethacin, may decrease the blood pressure-lowering capabilities of atenolol
• some medications used to treat mental illness, such as thioridazine
• some heart medications, such as amiodarone, clonidine, digoxin, diltiazem, propafenone, quinidine, and verapamil
• any other medication that may also lower blood pressure, such as amitriptyline, bupropion, furosemide, or HCTZ.

People taking oral medications for diabetes may need to talk to their doctor about adjusting the dose of their medicine.

Note that this list is not all-inclusive and includes only common medications that may interact with atenolol. You should refer to the prescribing information for atenolol for a complete list of interactions.

References

• Atenolol. Revised 07/2024. Major Pharmaceuticals https://www.drugs.com/pro/atenolol-tablets.html

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use atenolol only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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