Atenolol

atenolol (a ten' o lole) Apo-Atenolol (CAN), Gen-Atenolol (CAN), Novo-Atenol (CAN), Tenolin (CAN), Tenormin Pregnancy Category D Drug classes

Beta1-selective adrenergic blocking agent Antianginal Antihypertensive Therapeutic actions

Blocks beta-adrenergic receptors of the sympathetic nervous system in the heart and juxtaglomerular apparatus (kidney), thus decreasing the excitability of the heart, decreasing cardiac output and oxygen consumption, decreasing the release of renin from the kidney, and lowering blood pressure. Indications

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Treatment of angina pectoris due to coronary atherosclerosis Hypertension, as a step 1 agent, alone or with other drugs, especially diuretics Treatment of myocardial infarction Unlabeled uses: Prevention of migraine headaches; alcohol withdrawal syndrome, treatment of ventricular and supraventricular arrhythmias

Contraindications and cautions

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Contraindicated with sinus bradycardia, second- or third-degree heart block, cardiogenic shock, CHF. Use cautiously with renal failure, diabetes or thyrotoxicosis (atenolol can mask the usual cardiac signs of hypoglycemia and thyrotoxicosis), lactation, respiratory disease.

Available forms

Tablets—25, 50, 100 mg; injection—5 mg/10 mL Dosages ADULTS

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Hypertension: Initially, 50 mg PO once a day; after 1–2 wk, dose may be increased to 100 mg/day Angina pectoris: Initially, 50 mg PO daily. If optimal response is not achieved in 1 wk, increase to 100 mg daily; up to 200 mg/day may be needed. Acute MI: Initially, 5 mg IV given over 5 min as soon as possible after diagnosis; follow with IV injection of 5 mg 10 min later. Switch to 50 mg PO 10 min after the last IV dose; follow with 50 mg PO 12 hr later. Thereafter, administer 100 mg PO daily or 50 mg PO bid for 6–9 days or until discharge from the hospital.

PEDIATRIC PATIENTS

Safety and efficacy not established. GERIATRIC PATIENTS OR PATIENTS WITH RENAL IMPAIRMENT

Dosage reduction is required because atenolol is excreted through the kidneys. The following dosage is suggested: Creatinine Clearance mL/min 15–35 < 15

Half-life (hr)

Maximum Dosage

16–27 > 27

50 mg/day 25 mg/day

For patients on hemodialysis, give 50 mg after each dialysis; give only in hospital setting; severe hypotension can occur. Pharmacokinetics Route Oral IV

Onset Varies Immediate

Peak 2–4 hr 5 min

Duration 24 hr 24 hr

Metabolism: T1/2: 6–7 hr Distribution: Crosses placenta; enters breast milk Excretion: Urine (40%–50%) and bile and feces (50%–60%) IV facts

Preparation: May be diluted in dextrose injection, sodium chloride injection, or sodium chloride and dextrose injection. Stable for 48 hr after mixing. Infusion: Initiate treatment as soon as possible after admission to the hospital; inject 5 mg over 5 min; follow with another 5-mg IV injection 10 min later. Adverse effects

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Allergic reactions: Pharyngitis, erythematous rash, fever, sore throat, laryngospasm, respiratory distress CNS: Dizziness, vertigo, tinnitus, fatigue, emotional depression, paresthesias, sleep disturbances, hallucinations, disorientation, memory loss, slurred speech CV: Bradycardia, CHF, cardiac arrhythmias, sinoatrial or AV nodal block, tachycardia, peripheral vascular insufficiency, claudication, CVA, pulmonary edema, hypotension Dermatologic: Rash, pruritus, sweating, dry skin EENT: Eye irritation, dry eyes, conjunctivitis, blurred vision GI: Gastric pain, flatulence, constipation, diarrhea, nausea, vomiting, anorexia, ischemic colitis, renal and mesenteric arterial thrombosis, retroperitoneal fibrosis, hepatomegaly, acute pancreatitis GU: Impotence, decreased libido, Peyronie's disease, dysuria, nocturia, frequent urination Musculoskeletal: Joint pain, arthralgia, muscle cramp Respiratory: Bronchospasm, dyspnea, cough, bronchial obstruction, nasal stuffiness, rhinitis, pharyngitis (less likely than with propranolol)

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Other: Decreased exercise tolerance, development of antinuclear antibodies, hyperglycemia or hypoglycemia, elevated serum transaminase, alkaline phosphatase, and LDH

Interactions

Drug-drug • Increased effects with verapamil, anticholinergics, quinidine • Increased risk of orthostatic hypotension with prazosin • Increased risk of lidocaine toxicity with atenolol • Possible increased blood pressure-lowering effects with aspirin, bismuth subsalicylate, magnesium salicylate, sulfinpyrazone, hormonal contraceptives • Decreased antihypertensive effects with NSAIDs, clonidine • Decreased antihypertensive and antianginal effects of atenolol with ampicillin, calcium salts • Possible increased hypoglycemic effect of insulin Drug-lab test • Possible false results with glucose or insulin tolerance tests Nursing considerations Assessment

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History: Sinus bradycardia, second- or third-degree heart block, cardiogenic shock, CHF, renal failure, diabetes or thyrotoxicosis, lactation Physical: Baseline weight, skin condition, neurologic status, P, BP, ECG, respiratory status, kidney and thyroid function, blood and urine glucose, cholesterol, triglycerides

Interventions

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Do not discontinue drug abruptly after long-term therapy (hypersensitivity to catecholamines may have developed, causing exacerbation of angina, MI, and ventricular arrhythmias). Taper drug gradually over 2 wk with monitoring. Consult physician about withdrawing drug if patient is to undergo surgery (withdrawal is controversial).

Teaching points

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Take drug with meals if GI upset occurs. Do not stop taking this drug unless told to by a health care provider. Avoid driving or dangerous activities if dizziness, weakness occur. These side effects may occur: Dizziness, light-headedness, loss of appetite, nightmares, depression, sexual impotence. Report difficulty breathing, night cough, swelling of extremities, slow pulse, confusion, depression, rash, fever, sore throat.

Adverse effects in Italic are most common; those in Bold are life-threatening.