Brand name: Tenormin
Drug class: beta-Adrenergic Blocking Agents

Medically reviewed by Drugs.com on Jun 10, 2024. Written by ASHP.

Introduction

β₁-Selective adrenergic blocking agent.

Uses for Atenolol

Hypertension

Management of hypertension, alone or in combination with other classes of antihypertensive agents.

β-Adrenergic blocking agents (β-blockers) generally not preferred for first-line therapy of hypertension according to current evidence-based hypertension guidelines, but may be considered in patients who have a compelling indication (e.g., prior MI, ischemic heart disease, heart failure) for their use or as add-on therapy in those who do not respond adequately to the preferred drug classes (ACE inhibitors, angiotensin II receptor antagonists, calcium-channel blockers, or thiazide diuretics). A 2017 ACC/AHA multidisciplinary hypertension guideline states that β-blockers used for ischemic heart disease that are also effective in lowering BP include bisoprolol, carvedilol, metoprolol succinate, metoprolol tartrate, nadolol, propranolol, and timolol.

Some experts state that use of atenolol for hypertension should be avoided in patients with ischemic heart disease because the drug is less effective than placebo in reducing cardiovascular events and not as effective in treating hypertension as other antihypertensive drugs.

Individualize choice of therapy; consider patient characteristics (e.g., age, ethnicity/race, comorbidities, cardiovascular risk) as well as drug-related factors (e.g., ease of administration, availability, adverse effects, cost).

The 2017 ACC/AHA hypertension guideline classifies BP in adults into 4 categories: normal, elevated, stage 1 hypertension, and stage 2 hypertension. (See Table 1.)

Source: Whelton PK, Carey RM, Aronow WS et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018;71:e13-115

Individuals with SBP and DBP in 2 different categories (e.g., elevated SBP and normal DBP) should be designated as being in the higher BP category (i.e., elevated BP).

The goal of hypertension management and prevention is to achieve and maintain optimal control of BP. However, the BP thresholds used to define hypertension, the optimum BP threshold at which to initiate antihypertensive drug therapy, and the ideal target BP values remain controversial.

The 2017 ACC/AHA hypertension guideline generally recommends a target BP goal (i.e., BP to achieve with drug therapy and/or nonpharmacologic intervention) <130/80 mm Hg in all adults regardless of comorbidities or level of atherosclerotic cardiovascular disease (ASCVD) risk. In addition, an SBP goal of <130 mm Hg generally is recommended for noninstitutionalized ambulatory patients ≥65 years of age with an average SBP of ≥130 mm Hg. These BP goals are based upon clinical studies demonstrating continuing reduction of cardiovascular risk at progressively lower levels of SBP.

Other hypertension guidelines generally have based target BP goals on age and comorbidities. Guidelines such as those issued by the JNC 8 expert panel generally have targeted a BP goal of <140/90 mm Hg regardless of cardiovascular risk and have used higher BP thresholds and target BPs in elderly patients compared with those recommended by the 2017 ACC/AHA hypertension guideline.

Some clinicians continue to support previous target BPs recommended by JNC 8 due to concerns about the lack of generalizability of data from some clinical trials (e.g., SPRINT study) used to support the 2017 ACC/AHA hypertension guideline and potential harms (e.g., adverse drug effects, costs of therapy) versus benefits of BP lowering in patients at lower risk of cardiovascular disease.

Consider potential benefits of hypertension management and drug cost, adverse effects, and risks associated with the use of multiple antihypertensive drugs when deciding a patient’s BP treatment goal.

For decisions regarding when to initiate drug therapy (BP threshold), the 2017 ACC/AHA hypertension guideline incorporates underlying cardiovascular risk factors. ASCVD risk assessment recommended by ACC/AHA for all adults with hypertension.

ACC/AHA currently recommend initiation of antihypertensive drug therapy in addition to lifestyle/behavioral modifications at an SBP ≥140 mm Hg or DBP ≥90 mm Hg in adults who have no history of cardiovascular disease (i.e., primary prevention) and a low ASCVD risk (10-year risk <10%).

For secondary prevention in adults with known cardiovascular disease or for primary prevention in those at higher risk for ASCVD (10-year risk ≥10%), ACC/AHA recommend initiation of antihypertensive drug therapy at an average SBP ≥130 mm Hg or an average DBP ≥80 mm Hg.

Adults with hypertension and diabetes mellitus, chronic kidney disease (CKD), or age ≥65 years are assumed to be at high risk for cardiovascular disease; ACC/AHA states that such patients should have antihypertensive drug therapy initiated at a BP ≥130/80 mm Hg. Individualize drug therapy in patients with hypertension and underlying cardiovascular or other risk factors.

In stage 1 hypertension, experts state that it is reasonable to initiate drug therapy using the stepped-care approach in which one drug is initiated and titrated and other drugs are added sequentially to achieve the target BP. Initiation of antihypertensive therapy with 2 first-line agents from different pharmacologic classes recommended in adults with stage 2 hypertension and average BP >20/10 mm Hg above BP goal.

Black hypertensive patients generally tend to respond better to monotherapy with calcium-channel blockers or thiazide diuretics than to β-blockers. However, diminished response to β-blockers is largely eliminated when administered concomitantly with a thiazide diuretic.

Chronic Stable Angina

Long-term management of stable angina pectoris due to coronary atherosclerosis.

β-Blockers are recommended as first-line anti-ischemic drugs in most patients with chronic stable angina; despite differences in cardioselectivity, intrinsic sympathomimetic activity, and other clinical factors, all β-blockers appear to be equally effective for this use.

Non-ST-Segment-Elevation Acute Coronary Syndromes (NSTE ACS)

Used as part of the standard therapeutic measures for managing NSTE ACS, which include unstable angina and non-ST-segment-elevation MI (NSTEMI).

Expert guidelines recommend initiation of oral β-blocker therapy within the first 24 hours in patients who do not have manifestations of heart failure, evidence of low-output state, increased risk of cardiogenic shock, or any other contraindications to β-blocker therapy.

Continue β-blocker therapy for secondary prevention in patients with stabilized heart failure and reduced systolic function (preferably with bisoprolol, carvedilol, or metoprolol succinate because of proven mortality benefit).

Acute MI

Used during acute phase of MI to reduce cardiovascular mortality.

Expert guidelines recommend initiation of oral β-blocker therapy within the first 24 hours in patients who do not have manifestations of heart failure, evidence of low-output state, increased risk of cardiogenic shock, or any other contraindications to β-blocker therapy. Because of conflicting evidence of benefit and potential for harm (e.g., cardiogenic shock), experts recommend limiting use of IV β-blockers to patients with refractory hypertension or ongoing ischemia at time of presentation.

Continue β-blocker therapy for secondary prevention in post-MI patients with left ventricular systolic dysfunction (preferably with bisoprolol, carvedilol, or metoprolol succinate because of proven mortality benefit). Although benefits of long-term β-blockade in patients with normal left ventricular function are less well established, experts recommend continuing β-blocker therapy for at least 3 years in such patients.

Supraventricular Arrhythmias

Has been used in the treatment of supraventricular tachycardia^{† [off-label]} (SVT) (e.g., atrial flutter^{† [off-label]}, junctional tachycardia^{† [off-label]}, focal atrial tachycardia^{† [off-label]}, paroxysmal supraventricular tachycardia [PSVT]^{† [off-label]}).

Vagal maneuvers and/or IV adenosine are considered first-line interventions for acute treatment of SVT when clinically indicated; if such measures are ineffective or not feasible, may consider an IV β-adrenergic blocking agent. Oral β-blockers may be used for ongoing management. Although evidence of efficacy is limited, experts state that overall safety of β-adrenergic blockers warrants use.

Used to slow ventricular rate in patients with atrial fibrillation^† or flutter^†.

Ventricular Arrhythmias

β-Blockers have been used in patients with cardiac arrest precipitated by ventricular fibrillation^† or pulseless VT^† ; however, routine administration after cardiac arrest is potentially harmful and not recommended.

β-Blockers may be useful in the management of certain forms of polymorphic VT^† (e.g., associated with acute ischemia).

Vascular Headache

Prophylaxis of migraine headache^†.

Not recommended for the treatment of a migraine attack that has already started.

Alcohol Withdrawal

Management of acute alcohol withdrawal^† in conjunction with a benzodiazepine.

Atenolol should not be used as monotherapy for acute alcohol withdrawal^†.

Atenolol Dosage and Administration

General

• Individualize dosage according to patient response.

• β₁-Adrenergic blocking selectivity diminishes as dosage is increased.

• If long-term therapy is discontinued, reduce dosage gradually over a period of about 2 weeks.

BP Monitoring and Treatment Goals

• Monitor BP regularly (i.e., monthly) during therapy and adjust dosage of the antihypertensive drug until BP controlled.

• If unacceptable adverse effects occur, discontinue drug and initiate another antihypertensive agent from a different pharmacologic class.

• If adequate BP response not achieved with a single antihypertensive agent, either increase dosage of single drug or add a second drug with demonstrated benefit and preferably a complementary mechanism of action (e.g., ACE inhibitor, angiotensin II receptor antagonist, calcium-channel blocker, thiazide diuretic). Many patients will require at least 2 drugs from different pharmacologic classes to achieve BP goal; if goal BP still not achieved with 2 antihypertensive agents, add a third drug.

Administration

Administer orally; also has been administered by IV injection, however, a parenteral preparation no longer commercially available in US.

Once-daily dosing usually is sufficient in the management of hypertension.

Extemporaneous Liquid Formulation

An oral liquid formulation containing 2 mg/mL of atenolol has been extemporaneously prepared using the commercially available tablets and various vehicles (e.g., simple syrup, Ora-Sweet, Ora-Plus, Ora-Sweet SF, methylcellulose-based vehicle).

Standardize 4 Safety

Standardized concentrations for an extemporaneously prepared oral liquid formulation of atenolol have been established through Standardize 4 Safety (S4S), a national patient safety initiative to reduce medication errors, especially during transitions of care. Because recommendations from the S4S panels may differ from the manufacturer’s prescribing information, caution is advised when using concentrations that differ from labeling, particularly when using rate information from the label. For additional information on S4S (including updates that may be available), see [Web].

Dosage

Pediatric Patients

Hypertension†

Oral

Some experts have recommended an initial dosage of 0.5–1 mg/kg daily given as a single dose or in 2 divided doses. Increase dosage as necessary up to a maximum dosage of 2 mg/kg (up to 100 mg) daily given as a single dose or in 2 divided doses.

Adults

Hypertension

Atenolol Therapy

Oral

Initially, 50 mg once daily, alone or in combination with a diuretic recommended by manufacturer; full hypotensive effect usually seen within 1–2 weeks. If necessary, may increase dosage to 100 mg once daily.

Usual dosage range: Some experts state 25–100 mg daily, administered in 2 divided doses.

Atenolol/Chlorthalidone Fixed-combination Therapy

Oral

Initially, 50 mg of atenolol and 25 mg of chlorthalidone once daily. If response is not optimal, 100 mg of atenolol and 25 mg of chlorthalidone once daily.

Manufacturer states fixed-combination preparation is not recommended for initial therapy; administer each drug separately, then use the fixed combination if the optimum maintenance dosage corresponds to the ratio of drugs in the combination preparation.

May add another antihypertensive agent when necessary (gradually using half of the usual initial dosage to avoid an excessive decrease in BP).

Chronic Stable Angina

Oral

Initially, 50 mg once daily.

If optimum response is not achieved within 1 week, increase to 100 mg once daily.

Some patients may require 200 mg once daily for optimum effect.

Acute MI

Early Treatment

May initiate therapy as soon as possible after patient’s hemodynamic condition has stabilized.

In patients with definite or suspected MI, atenolol has been initiated with IV doses; however, a parenteral preparation no longer commercially available in US.

Oral

Manufacturer recommends 50 mg twice daily or 100 mg once daily for at least 7 days.

Long-term Secondary Prevention

Oral

Optimal duration of therapy for secondary prevention remains to be clearly established. Experts generally recommend long-term therapy in post-MI patients with left ventricular systolic dysfunction, and at least 3 years of therapy in those with normal left ventricular function.

Supraventricular Arrhythmias†

SVT (e.g., PSVT†, Atrial Flutter†, Junctional Tachycardia†, Atrial Tachycardia†) or Atrial Fibrillation†

Oral

Some experts recommend an initial dose of 25–50 mg daily and usual maintenance dosage of 25–100 mg daily for ongoing therapy.

Vascular Headache†

Prevention of Common Migraine†

Oral

Dosage has not been established; in clinical studies 100 mg daily was usual effective dosage.

Special Populations

Hepatic Impairment

Minimal hepatic metabolism; no dosage adjustment recommended.

Renal Impairment

Hypertension

Oral

Modify dose and/or frequency of administration in response to the degree of renal impairment.

Initial dosage of 25 mg daily may be necessary.

Measure BP just prior to the dose to ensure persistence of adequate BP reduction.

Patients with Cl_cr 15–35 mL/minute per 1.73 m²: Maximum 50 daily.

Patients with Cl_cr<15 mL/minute per 1.73 m²: Maximum 25 mg daily or 50 mg every other day.

Hemodialysis patients: May administer 25 or 50 mg after each dialysis. Marked reductions in BP may occur; give under careful supervision.

Geriatric Patients

Hypertension

Modification of dosage may be necessary because of age-related decreases in renal function.

Initially, 25 mg daily may be necessary.

Measure BP just prior to a dose to ensure persistence of adequate BP reduction.

Bronchospastic Disease

Initially, 50 mg daily and use lowest possible dosage. If dosage must be increased, consider administering in 2 divided doses daily to decrease peak blood levels. A β₂-adrenergic agonist bronchodilator should be available. (See Bronchospastic Disease under Cautions.)

Cautions for Atenolol

Contraindications

• Patients with sinus bradycardia, AV block greater than first degree, cardiogenic shock, overt or decompensated cardiac failure. Patients with acute MI not promptly and effectively controlled by 80 mg IV furosemide or equivalent therapy.

• Do not use in patients with untreated pheochromocytoma.

• Hypersensitivity to atenolol or any ingredient in the formulation.

Warnings/Precautions

Warnings

Heart Failure

Possible precipitation of heart failure; possible decreased exercise tolerance in patients with left ventricular dysfunction.

Initiate therapy and subsequent dosage adjustments in patients with heart failure under close medical supervision. Prior to initiation of the drug, stabilize patient on other therapy (e.g., ACE inhibitor, diuretic, and/or cardiac glycoside). Symptomatic improvement may not be evident for 2–3 months after initiating therapy.

Avoid use in patients with decompensated heart failure; use cautiously in patients with inadequate myocardial function and, if necessary, in patients with well-compensated heart failure (e.g., those controlled with ACE inhibitors, cardiac glycosides, and/or diuretics); use with extreme caution in patients with substantial cardiomegaly.

Adequate treatment (e.g., with a cardiac glycoside and/or diuretic) and close observation recommended if signs or symptoms of impending cardiac failure occur; if cardiac failure continues, discontinue therapy, gradually if possible.

History of Anaphylactic Reactions

Possible increased reactivity to a variety of allergens; patients may be unresponsive to usual doses of epinephrine used to treat anaphylactic reactions.

Calcium-channel Blocking Agents

Concomitant use may cause bradycardia, heart block, increased left ventricular and diastolic blood pressure, particularly in patients with preexisting conduction abnormalities or left ventricular dysfunction. (See Specific Drugs under Interactions.)

Bronchospastic Disease

Possible bronchoconstriction, especially at dosages >100 mg daily. Cautious use recommended in patients with bronchospastic disease (patients who do not respond to or cannot tolerate other hypotensive agents).

Initiate therapy with 50 mg daily and use lowest possible dosage; β₁-selectivity is not absolute. Twice-daily dosing and concomitant use of a β₂-adrenergic agonist bronchodilator may minimize risk of bronchospasm.

If bronchospasm occurs, reduce dosage or discontinue atenolol (gradually if possible) and administer supportive treatment.

Anesthesia and Major Surgery

Possible increased risks associated with general anesthesia. (See Specific Drugs under Interactions.)

Withdrawal of β-blocker prior to surgery is not recommended in most patients.

Correct vagal dominance (if any) with atropine (1–2 mg IV).

Atenolol effects can be reversed by cautious administration of β-agonists (e.g., dobutamine, isoproterenol).

Diabetes and Hypoglycemia

Possible decreased signs and symptoms of hypoglycemia, particularly tachycardia.

β₁-Selective atenolol does not potentiate insulin-induced hypoglycemia or delay recovery of blood glucose to normal levels.

Thyrotoxicosis

Signs of hyperthyroidism (e.g., tachycardia) may be masked.

Possible thyroid storm if therapy is abruptly withdrawn; carefully monitor patients having or suspected of developing thyrotoxicosis.

General Precautions

Peripheral Arterial Circulatory Disorders

May be aggravated.

Other Precautions

Atenolol shares the toxic potentials of β-blockers; observe usual precautions of these agents.

When used in fixed combination with chlorthalidone, consider the cautions, precautions, and contraindications associated with thiazide diuretics.

Specific Populations

Pregnancy

Category D.

Lactation

Distributed into milk; caution if used in nursing women.

Pediatric Use

Safety and efficacy remain to be fully established in children; however, some experts have recommended dosages for hypertension based on clinical experience.

Geriatric Use

Response in patients ≥65 years of age does not appear to differ from that in younger adults; however, use with caution due to greater frequency of decreased hepatic, renal, and/or cardiac function and of concomitant disease and drug therapy observed in the elderly.

Consider age-related decreases in renal function when selecting dosage and adjust dosage if necessary. Evaluation of geriatric patients with hypertension or MI should always include assessment of renal function. (See Geriatric Patients under Dosage and Administration.)

Renal Impairment

Decreased clearance; use with caution and adjust dosage based on degree of renal impairment. (See Renal Impairment under Dosage and Administration.)

Common Adverse Effects

Tiredness, hypotension, heart failure, bradycardia, ventricular tachycardia, dizziness, cold extremities, depression, supraventricular tachycardia (atrial fibrillation or flutter), bundle branch block and major axis deviation, fatigue, dyspnea.

Drug Interactions

Specific Drugs

Atenolol Pharmacokinetics

Absorption

Bioavailability

50–60% following oral administration.

Onset

1 hour following oral administration. Within 5 minutes following IV administration.

Duration

At least 24 hours following oral administration (antihypertensive and β-adrenergic blocking effects). About 12 hours following IV administration (effect on heart rate).

Special Populations

In geriatric patients, plasma concentrations are increased.

Distribution

Extent

Well distributed into most tissues and fluids except brain and CSF.

Readily crosses the placenta, has been detected in cord blood.

Distributed into milk in concentrations higher than those in serum.

Plasma Protein Binding

Approximately 6–16%.

Elimination

Metabolism

Little or no hepatic metabolism.

Elimination Route

40–50% excreted unchanged in urine following oral administration; remainder in feces, principally as unabsorbed drug.

Half-life

6–7 hours.

Special Populations

In patients with Cl_cr 15–35 mL/minute per 1.73 m², plasma half-life is increased to 16–27 hours; in progressive renal impairment plasma half-life is >27 hours.

In geriatric patients, total clearance is decreased by about 50%, plasma half-life is prolonged.

Hemodialysis: 1–12% removed.

Stability

Storage

Oral

Tablets

Tight, light-resistant containers at 20–25°.

Tablets (Atenolol and Chlorthalidone)

Tight, light-resistant containers at 20–25°.

Actions

• Inhibits response to adrenergic stimuli by competitively blocking β₁-adrenergic receptors within the myocardium. Blocks β₂-adrenergic receptors within bronchial and vascular smooth muscle only in high doses (e.g., >100 mg daily).

• Decreases resting and exercise-stimulated heart rate and reflex orthostatic tachycardia by about 25–35%. Slows AV nodal conduction.

• No intrinsic sympathomimetic activity and little or no membrane-stabilizing effect on the heart.

• Reduces BP by decreasing cardiac output, suppressing renin release, and/or decreasing sympathetic outflow from the CNS.

• In patients with angina pectoris, blocks catecholamine-induced increases in heart rate, myocardial contractility, and BP, resulting in decreased myocardial oxygen consumption.

• Possibly increases oxygen requirements in patients with heart failure due to increased left ventricular fiber length and end diastolic pressure.

• Increases airway resistance (at doses >100 mg) in patients with asthma and/or COPD.

• Produces little or no changes in serum insulin concentrations, time to recovery from insulin-induced hypoglycemia, or free fatty acid response to hypoglycemia.

Advice to Patients

• Importance of taking medication exactly as prescribed.

• Importance of not interrupting or discontinuing therapy without consulting clinician.

• If a dose is missed, importance of patient taking only the next scheduled dose (i.e., the next dose should not be doubled).

• Importance of advising patients with coronary artery disease to temporarily limit their physical activity when discontinuing therapy.

• Importance of immediately informing clinician at the first sign or symptom of impending cardiac failure (e.g., weight gain, increased shortness of breath) or if any difficulty in breathing occurs.

• Importance of patients undergoing major surgery informing anesthesiologist or dentist they are receiving the drug.

• Importance of informing clinicians of existing or contemplated therapy, including prescription and OTC drugs.

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

• Importance of clinician informing women who are or plan to become pregnant of risk to fetus.

• Importance of informing patient of other important precautionary information. (See Cautions.)

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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Frequently asked questions

• What is the best time of day to take blood pressure medication?
• How is atenolol superior to metoprolol?

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