Atenolol

Atenolol is a beta blocker medication primarily used to treat high blood pressure and heart-associated chest pain. Although used to treat high blood pressure, it does not seem to improve mortality in those with the condition.[2][3] Other uses include the prevention of migraines and treatment of certain irregular heart beats.[4] It is taken orally (by mouth) or by intravenous injection (injection into a vein).[4] It can also be used with other blood pressure medications.[4]

Common side effects include feeling tired, heart failure, dizziness, depression, and shortness of breath. Other serious side effects include bronchial spasm. Use is not recommended during pregnancy and alternative drugs are preferred when breastfeeding.[5] It works by blocking β1-adrenergic receptors in the heart, thus decreasing heart rate, force of heart beats, and blood pressure.

Atenolol was patented in 1969 and approved for medical use in 1975.[6] It is on the World Health Organization's List of Essential Medicines.[7] It is available as a generic medication.[8] In 2023, it was the 75th most commonly prescribed medication in the United States, with more than 9million prescriptions.[9][10]

Medical uses

Atenolol is used for a number of conditions including hyperthyroidism,[11] hypertension, angina, long QT syndrome, acute myocardial infarction, supraventricular tachycardia, ventricular tachycardia, essential tremor (ET), and the symptoms of alcohol withdrawal.[12]

The role for β-blockers in general in hypertension was downgraded in June 2006 in the United Kingdom, and later in the United States, as they are less appropriate than other agents such as ACE inhibitors, calcium channel blockers, thiazide diuretics and angiotensin receptor blockers, particularly in the elderly.[13][14][15]

Atenolol has been used to treat anxiety disorders, such as generalized anxiety disorder and social anxiety disorder.[16][17][18] It is thought that beta blockers do not directly treat psychological symptoms of anxiety, but can help control physical symptoms such as palpitations, and this may interfere with a positive feedback loop to indirectly reduce psychological anxiety.[16] A 2025 systematic review and meta-analysis that included atenolol found widespread prescription of beta blockers for treatment anxiety disorders, but found no evidence of a beneficial effect relative to placebo or benzodiazepines in people with social phobia or panic disorder.[16] However, the quality of evidence, including both numbers of studies and patients as well as quality and risk of bias of those studies, was limited.[16]

Contraindications

Contraindications of atenolol include sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt heart failure. There is no basis for use of atenolol in people with heart rate of lower than 50bpm or systolic blood pressure of less than 100mmHg and hence these can be considered contraindications. It is also contraindicated in people with a history of hypersensitivity to atenolol or any of the drug product's other components.

Side effects

Hypertension treated with a β-blocker such as atenolol, alone or in conjunction with a thiazide diuretic, is associated with a higher incidence of new onset type 2 diabetes mellitus compared to those treated with an ACE inhibitor or angiotensin receptor blocker.[19][20]

β-blockers, of which atenolol is mainly studied, provides weaker protection against stroke and mortality in patients over 60 years old compared to other antihypertensive medications.[21][22][23][13] Diuretics may be associated with better cardiovascular and cerebrovascular outcomes than β-blockers in the elderly.[24]

Rarely, atenolol has been associated with induction of acute delirium.[25][26][27]

Overdose

Symptoms of overdose are due to excessive pharmacodynamic actions on β1 and also β2-receptors. These include bradycardia (slow heartbeat), severe hypotension with shock, acute heart failure, hypoglycemia and bronchospastic reactions. Treatment is largely symptomatic. Hospitalization and intensive monitoring is indicated. 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 such as hexoprenalin or salbutamol will terminate bronchospasms. Blood or plasma atenolol concentrations may be measured to confirm a diagnosis of poisoning in hospitalized patients or to assist in a medicolegal death investigation. Plasma levels are usually less than 3 mg/L during therapeutic administration, but can range from 3–30 mg/L in overdose victims.[28][29]

Interactions

Interactions with atenolol include catecholamine-depleting drugs like reserpine, calcium channel blockers, disopyramide, amiodarone, clonidine, prostaglandin synthase inhibitors like indomethacin, and digitalis glycosides.[30] Most of these interactions involve either additive cardiovascular effects or reduction of atenolol's effects.[30]

Atenolol is mainly eliminated renally without being metabolized by the liver or by cytochrome P450 enzymes.[30][31][32] As a result, it has little or no potential for cytochrome P450-related drug interactions, for instance with inhibitors and inducers of these enzymes.[31][32] Accordingly, the broad/non-selective cytochrome P450 inhibitor cimetidine had no effect on atenolol levels, whereas cimetidine has been found to significantly increase metoprolol and propranolol levels.[31]

Beta blockers like atenolol can reduce or block the cardiovascular effects of sympathomimetics and amphetamines, such as hypertension and tachycardia.[33][34][35][36][37][38][39]

Atenolol has been found to be safe in combination with the non-selective monoamine oxidase inhibitor (MAOI) phenelzine and actually improved orthostatic hypotension and hypertensive reactions with phenelzine.[40][41][42] However, more research is still needed to assess whether addition of a beta blocker like atenolol to MAOI therapy is safe and effective for improving orthostatic hypotension with MAOIs.[40][42]

Pharmacology

Chemistry

Atenolol is a substituted phenethylamine derivative. It is specifically β-phenylethylamine with an α-keto substitution and a 4- substitution on the phenyl ring.

The experimental log P of atenolol is 0.16 and its predicted log P ranges from −0.03 to 0.57.[49][50][51] Atenolol showed the lowest predicted lipophilicity of 30clinically relevant beta blockers.[52]

History

Atenolol was patented in 1969 and was approved for medical use in 1975.[6]

Society and culture