ATENOLOL

ATENOLOL (a-ten'oh-lole) Apo-Atenolol , Tenormin Classifications: beta-adrenergic antagonist; antihypertensive agent; Therapeutic: antihypertensive Prototype: Propranolol Pregnancy Category: D

Availability

25 mg, 50 mg, 100 mg tablets; 5 mg/10 mL vial

Action

Atenolol selectively blocks beta₁-adrenergic receptors located chiefly in cardiac muscle. Mechanisms for antihypertensive action include central effect leading to decreased sympathetic outflow to periphery, reduction in renin activity with consequent suppression of the renin-angiotensin-aldosterone system, and competitive inhibition of catecholamine binding at beta-adrenergic receptor sites.

Therapeutic Effect

Reduces rate and force of cardiac contractions (negative inotropic action); cardiac output is reduced, as well as systolic and diastolic BP. Atenolol decreases peripheral vascular resistance both at rest and with exercise.

Uses

Management of hypertension as a single agent or concomitantly with other antihypertensive agents, especially a diuretic, and in treatment of stable angina pectoris, MI.

Unlabeled Uses

Antiarrhythmic, mitral valve prolapse, adjunct in treatment of pheochromocytoma and of thyrotoxicosis; and for vascular headache prophylaxis.

Contraindications

Sinus bradycardia, greater than first-degree AV heart block, uncompensated heart failure, cardiogenic shock, peripheral vascular disease, Raynaud's disease, hypotension; abrupt discontinuation, pulmonary edema, acute bronchospasm; pregnancy (category D), lactation.

Cautious Use

Hypertensive patients with CHF controlled by digitalis and diuretics, vasospastic angina (Prinzmetal's angina); asthma, bronchitis, emphysema, and COPD; major depression; diabetes mellitus; impaired renal function, dialysis; myasthenia gravis; pheochromocytoma, hyperthyroidism, thyrotoxicosis; older adults.

Route & Dosage

Hypertension, Angina Adult: PO 25–50 mg/d, may increase to 100 mg/d Child: PO 0.8–1.5 mg/kg/d (max: 2 mg/kg/d) MI Adult: PO 10 min after second IV dose, start 50 mg/d IV 5 mg q5min times 2 doses, then switch to PO Renal Impairment Clcr 15–35 mL/min: max dose of 50 mg/d; <15 mL/min: max dose of 25 mg/d

Administration

Oral

• Crush tablets, if necessary, before administration and give with fluid of patient's choice.

Intravenous PREPARE: Direct: Use undiluted or diluted in 10–50 mL of NS, D5W, D5/NS, D5/0.45NS, or 0.45NaCl.   ADMINISTER: Direct: Give over 5 min. Do not exceed 1 mg/min.   INCOMPATIBILITIES Y-site: Amphotericin B cholesteryl complex

• Store in tightly closed, light-resistant container at 15°–30° C (59°–86° F) unless otherwise directed.

Adverse Effects (≥1%)

CNS: Dizziness, vertigo, light-headedness, syncope, fatigue or weakness, lethargy, drowsiness, insomnia, mental changes, depression. CV: Bradycardia, hypotension, CHF, cold extremities, leg pains, dysrhythmias. GI: Nausea, vomiting, diarrhea. Respiratory: Pulmonary edema, dyspnea, bronchospasm. Other: May mask symptoms of hypoglycemia; decreased sexual ability.

Interactions

Drug: Atropine and other anticholinergics may increase atenolol absorption from GI tract; nsaids may decrease hypotensive effects; may mask symptoms of a hypoglycemic reaction induced by insulin, sulfonylureas; may increase lidocaine levels and toxicity; pharmacologic and toxic effects of both atenolol and verapamil are increased. Prazosin, terazocin may increase severe hypotensive response to first dose of atenolol.

Pharmacokinetics

Absorption: 50% of PO dose absorbed. Peak: 2–4 h PO; 5 min IV. Duration: 24 h. Distribution: Does not readily cross blood–brain barrier. Metabolism: No hepatic metabolism. Elimination: 40–50% in urine; 50–60% in feces. Half-Life: 6–7 h.

Nursing Implications

Assessment & Drug Effects

• Neonates born to mothers who are receiving atenolol at parturition or breast-feeding may be at risk for hypoglycemia.
• Check apical pulse before giving oral drug, especially in patients receiving digitalis (both drugs slow AV conduction). If below 60 bpm (or other ordered parameter), withhold dose and consult physician.
• Monitor apical pulse, BP, respirations, and peripheral circulation throughout dosage adjustment period. Consult physician for acceptable parameters.

Patient & Family Education

• Adhere rigidly to dose regimen. Sudden discontinuation of drug can exacerbate angina and precipitate tachycardia or MI in patients with coronary artery disease, and thyroid storm in patients with hyperthyroidism.
• Make position changes slowly and in stages, particularly from recumbent to upright posture.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug