Atenolol

Action

Selectively blocks beta₁-adrenergic (myocardial) receptors; decreases cardiac output, peripheral resistance, and myocardial oxygen consumption. Also depresses renin secretion without affecting beta₂-adrenergic (pulmonary, vascular, uterine) receptors.

Availability

Tablets: 25 mg, 50 mg, 100 mg

Indications and dosages

➣ Hypertension

Adults: Initially, 50 mg P.O. once daily, increased to 100 mg after 7 to 14 days if needed

➣ Angina pectoris

Adults: Initially, 50 mg P.O. once daily, increased to 100 mg after 7 days if needed. Some patients may require up to 200 mg daily.

➣ Acute myocardial infarction

Adults: 50 mg tablet P.O., then give 50 mg P.O. in 12 hours. Maintenance dosage is 100 mg P.O. daily or 50 mg b.i.d. for 6 to 9 days.

Dosage adjustment

• Renal impairment

• Elderly patients

Contraindications

• Cardiogenic shock

• Sinus bradycardia

• Greater than first-degree heart block

• Heart failure (unless secondary to tachyarrhythmia treatable with beta-adrenergic blockers)

Precautions

Use cautiously in:

• renal failure, hepatic impairment, pulmonary disease, diabetes mellitus, thyrotoxicosis

• pregnant or breastfeeding patients

• children.

Administration

☞ Adjust initial and subsequent dosages downward depending on clinical observations, including pulse rate and blood pressure.

☞ Don't discontinue drug suddenly. Instead, taper dosage over 2 weeks.

Adverse reactions

CNS: fatigue, lethargy, vertigo, drowsiness, dizziness, depression, disorientation, short-term memory loss

CV: hypertension, intermittent claudication, cold arms and legs, orthostatic hypotension, bradycardia, arrhythmias, heart failure, cardiogenic shock, myocardial reinfarction

EENT: blurred vision, dry eyes, eye irritation, conjunctivitis, stuffy nose, rhinitis, pharyngitis, laryngospasm

GI: nausea, vomiting, diarrhea, constipation, gastric pain, flatulence, anorexia, ischemic colitis, retroperitoneal fibrosis, acute pancreatitis, mesenteric arterial thrombosis

GU: impotence, decreased libido, dysuria, nocturia, Peyronie's disease, renal failure

Hematologic: agranulocytosis

Hepatic: hepatomegaly

Metabolic: hypoglycemia

Musculoskeletal: muscle cramps, back and joint pain

Respiratory: dyspnea, wheezing, respiratory distress, bronchospasm, bronchial obstruction, pulmonary emboli

Other: decreased exercise tolerance, allergic reaction, fever, development of antinuclear antibodies, hypersensitivity reaction

Interactions

Drug-drug. Amiodarone, cardiac glycosides, diltiazem, verapamil: increased myocardial depression, causing excessive bradycardia and heart block

Amphetamines, cocaine, ephedrine, norepinephrine, phenylephrine, pseudoephedrine: excessive hypertension, bradycardia

Ampicillin, calcium salts: decreased antihypertensive and antianginal effects

Aspirin, bismuth subsalicylate, magnesium salicylate, nonsteroidal anti-inflammatory drugs: decreased anti-hypertensive effect

Clonidine: life-threatening blood pressure increase after clonidine withdrawal or simultaneous withdrawal of both drugs

Dobutamine, dopamine: decrease in beneficial beta-cardiovascular effects

Lidocaine: increased lidocaine levels, greater risk of toxicity

MAO inhibitors: bradycardia Prazosin: increased risk of orthostatic hypotension

Reserpine: increased hypotension, marked bradycardia

Theophylline: decreased theophylline elimination

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, antinuclear antibody titer, blood urea nitrogen, creatinine, lactate dehydrogenase, platelets, potassium, uric acid: increased levels

Glucose: increased or decreased level

Insulin tolerance test: false result

Drug-behaviors. Alcohol use: increased hypotension

Patient monitoring

• Watch for signs and symptoms of hypersensitivity reaction.

• Monitor vital signs (especially blood pressure), ECG, and exercise tolerance.

• Check closely for hypotension in hemodialysis patients.

• Monitor blood glucose level regularly if patient is diabetic; drug may mask signs and symptoms of hypoglycemia.

Patient teaching

☞ Instruct patient to immediately report signs and symptoms of allergic response, breathing problems, and chest pain.

• Advise patient to take drug at same time every day.

☞ Inform patient that he may experience serious reactions if he stops taking drug suddenly. Advise him to consult prescriber before discontinuing.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Tell patient that drug may cause a temporary blood pressure decrease if he stands or sits up suddenly. Instruct him to rise slowly and carefully.

• Inform women that drug shouldn't be taken during pregnancy. Urge them to report planned or suspected pregnancy.

• Tell men that drug may cause erectile dysfunction. Advise them to discuss this issue with prescriber.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and behaviors mentioned above.