Cessation of Therapy With Atenolol Patients with coronary artery disease, who are being treated with atenolol, should be advised against abrupt discontinuation of therapy. Severe exacerbation of angina and the occurrence of myocardial infarction and ventricular arrhythmias have been reported in angina patients following the abrupt discontinuation of therapy with beta blockers. The last two complications may occur with or without preceding exacerbation of the angina pectoris. As with other beta blockers, when discontinuation of atenolol is planned, the patients should be carefully observed and advised to limit physical activity to a minimum. If the angina worsens or acute coronary insufficiency develops, it is recommended that atenolol be promptly reinstituted, at least temporarily. Because coronary artery disease is common and may be unrecognized, it may be prudent not to discontinue atenolol therapy abruptly even in patients treated only for hypertension (see DOSAGE AND ADMINISTRATION ).
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warnings
WARNINGS Cardiac Failure Sympathetic stimulation is necessary in supporting circulatory function in congestive heart failure, and beta blockade carries the potential hazard of further depressing myocardial contractility and precipitating more severe failure. In patients with acute myocardial infarction, cardiac failure which is not promptly and effectively controlled by 80 mg of intravenous furosemide or equivalent therapy is a contraindication to beta-blocker treatment. In Patients Without a History of Cardiac Failure Continued depression of the myocardium with beta-blocking agents over a period of time can, in some cases, lead to cardiac failure. At the first sign or symptom of impending cardiac failure, patients should be treated appropriately according to currently recommended guidelines, and the response observed closely. If cardiac failure continues despite adequate treatment, atenolol should be withdrawn (see DOSAGE AND ADMINISTRATION ). Cessation of Therapy With Atenolol Patients with coronary artery disease, who are being treated with atenolol, should be advised against abrupt discontinuation of therapy. Severe exacerbation of angina and the occurrence of myocardial infarction and ventricular arrhythmias have been reported in angina patients following the abrupt discontinuation of therapy with beta blockers. The last two complications may occur with or without preceding exacerbation of the angina pectoris. As with other beta blockers, when discontinuation of atenolol is planned, the patients should be carefully observed and advised to limit physical activity to a minimum. If the angina worsens or acute coronary insufficiency develops, it is recommended that atenolol be promptly reinstituted, at least temporarily. Because coronary artery disease is common and may be unrecognized, it may be prudent not to discontinue atenolol therapy abruptly even in patients treated only for hypertension (see DOSAGE AND ADMINISTRATION ). Concomitant Use of Calcium Channel Blockers Bradycardia and heart block can occur and the left ventricular end diastolic pressure can rise when beta-blockers are administered with verapamil or diltiazem. Patients with preexisting conduction abnormalities or left ventricular dysfunction are particularly susceptible (see PRECAUTIONS ). Bronchospastic Diseases PATIENTS WITH BRONCHOSPASTIC DISEASE SHOULD, IN GENERAL, NOT RECEIVE BETA BLOCKERS. Because of its relative beta 1 selectivity, however, atenolol may be used with caution in patients with bronchospastic disease who do not respond to, or cannot tolerate, other antihypertensive treatment. Since beta 1 selectivity is not absolute, the lowest possible dose of atenolol should be used with therapy initiated at 50 mg and a beta 2 -stimulating agent (bronchodilator) should be made available. If dosage must be increased, dividing the dose should be considered in order to achieve lower peak blood levels. Major Surgery Chronically administered beta-blocking therapy should not be routinely withdrawn prior to major surgery; however, the impaired ability of the heart to respond to reflex adrenergic stimuli may augment the risks of general anesthesia and surgical procedures. Diabetes and Hypoglycemia Atenolol should be used with caution in diabetic patients if a beta-blocking agent is required. Beta blockers may mask tachycardia occurring with hypoglycemia, but other manifestations such as dizziness and sweating may not be significantly affected. At recommended doses atenolol does not potentiate insulin-induced hypoglycemia and, unlike nonselective beta blockers, does not delay recovery of blood glucose to normal levels. Thyrotoxicosis Beta-adrenergic blockade may mask certain clinical signs (e.g., tachycardia) of hyperthyroidism. Abrupt withdrawal of beta blockade might precipitate a thyroid storm; therefore, patients suspected of developing thyrotoxicosis from whom atenolol therapy is to be withdrawn should be monitored closely (see DOSAGE AND ADMINISTRATION ). Untreated Pheochromocytoma Atenolol should not be given to patients with untreated pheochromocytoma. Pregnancy and Fetal Injury Atenolol can cause fetal harm when administered to a pregnant woman. Atenolol crosses the placental barrier and appears in cord blood. Administration of atenolol, starting in the second trimester of pregnancy, has been associated with the birth of infants that are small for gestational age. No studies have been performed on the use of atenolol in the first trimester and the possibility of fetal injury cannot be excluded. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus. Neonates born to mothers who are receiving atenolol at parturition or breastfeeding may be at risk for hypoglycemia and bradycardia. Caution should be exercised when atenolol is administered during pregnancy or to a woman who is breastfeeding (see PRECAUTIONS, Nursing Mothers ). Atenolol has been shown to produce a dose-related increase in embryo/fetal resorptions in rats at doses equal to or greater than 50 mg/kg/day or 25 or more times the maximum recommended human antihypertensive dose. * Although similar effects were not seen in rabbits, the compound was not evaluated in rabbits at doses above 25 mg/kg/day or 12.5 times the maximum recommended human antihypertensive dose. * * Based on the maximum dose of 100 mg/day in a 50 kg patient.
ADVERSE REACTIONS Most adverse effects have been mild and transient. The frequency estimates in the following table were derived from controlled studies in hypertensive patients in which adverse reactions were either volunteered by the patient (U.S. studies) or elicited, e.g., by checklist (foreign studies). The reported frequency of elicited adverse effects was higher for both atenolol and placebo-treated patients than when these reactions were volunteered. Where frequency of adverse effects of atenolol and placebo is similar, causal relationship to atenolol is uncertain. Volunteered (U.S. Studies) Total - Volunteered and Elicited (Foreign + U.S. Studies) Atenolol (n = 164) Placebo (n = 206) Atenolol (n = 399) Placebo (n = 407) % % % % CARDIOVASCULAR Bradycardia 3 0 3 0 Cold Extremities 0 0.5 12 5 Postural Hypotension 2 1 4 5 Leg Pain 0 0.5 3 1 CENTRAL NERVOUS SYSTEM/NEUROMUSCULAR Dizziness 4 1 13 6 Vertigo 2 0.5 2 0.2 Light-headedness 1 0 3 0.7 Tiredness 0.6 0.5 26 13 Fatigue 3 1 6 5 Lethargy 1 0 3 0.7 Drowsiness 0.6 0 2 0.5 Depression 0.6 0.5 12 9 Dreaming 0 0 3 1 GASTROINTESTINAL Diarrhea 2 0 3 2 Nausea 4 1 3 1 RESPIRATORY (see WARNINGS ) Wheeziness 0 0 3 3 Dyspnea 0.6 1 6 4 Acute Myocardial Infarction In a series of investigations in the treatment of acute myocardial infarction, bradycardia and hypotension occurred more commonly, as expected for any beta blocker, in atenolol-treated patients than in control patients. However, these usually responded to atropine and/or to withholding further dosage of atenolol. The incidence of heart failure was not increased by atenolol. Inotropic agents were infrequently used. The reported frequency of these and other events occurring during these investigations is given in the following table. In a study of 477 patients, the following adverse events were reported during either intravenous and/or oral atenolol administration: Conventional Therapy Plus Atenolol (n = 244) Conventional Therapy Alone (n = 233) Bradycardia 43 (18%) 24 (10%) Hypotension 60 (25%) 34 (15%) Bronchospasm 3 (1.2%) 2 (0.9%) Heart Failure 46 (19%) 56 (24%) Heart Block 11 (4.5%) 10 (4.3%) BBB + Major Axis Deviation 16 (6.6%) 28 (12%) Supraventricular Tachycardia 28 (11.5%) 45 (19%) Atrial Fibrillation 12 (5%) 29 (11%) Atrial Flutter 4 (1.6%) 7 (3%) Ventricular Tachycardia 39 (16%) 52 (22%) Cardiac Reinfarction 0 (0%) 6 (2.6%) Total Cardiac Arrests 4 (1.6%) 16 (6.9%) Nonfatal Cardiac Arrests 4 (1.6%) 12 (5.1%) Deaths 7 (2.9%) 16 (6.9%) Cardiogenic Shock 1 (0.4%) 4 (1.7%) Development of Ventricular Septal Defect 0 (0%) 2 (0.9%) Development of Mitral Regurgitation 0 (0%) 2 (0.9%) Renal Failure 1 (0.4%) 0 (0%) Pulmonary Emboli 3 (1.2%) 0 (0%) In the subsequent International Study of Infarct Survival (ISIS-1) including over 16,000 patients of whom 8,037 were randomized to receive atenolol treatment, the dosage of intravenous and subsequent oral atenolol was either discontinued or reduced for the following reasons: Reasons for Reduced Dosage IV Atenolol Reduced Dose (< 5 mg) Full dosage was 10 mg and some patients received less than 10 mg but more than 5 mg. Oral Partial Dose Hypotension/Bradycardia 105 (1.3%) 1168 (14.5%) Cardiogenic Shock 4 (0.04%) 35 (0.44%) Reinfarction 0 (0%) 5 (0.06%) Cardiac Arrest 5 (0.06%) 28 (0.34%) Heart Block (> first degree) 5 (0.06%) 143 (1.7%) Cardiac Failure 1 (0.01%) 233 (2.9%) Arrhythmias 3 (0.04%) 22 (0.27%) Bronchospasm 1 (0.01%) 50 (0.62%) During postmarketing experience with atenolol, the following have been reported in temporal relationship to the use of the drug: elevated liver enzymes and/or bilirubin, hallucinations, headache, impotence, Peyronie's disease, postural hypotension which may be associated with syncope, psoriasiform rash or exacerbation of psoriasis, psychoses, purpura, reversible alopecia, thrombocytopenia, visual disturbance, sick sinus syndrome, and dry mouth. Atenolol, like other beta blockers, has been associated with the development of antinuclear antibodies (ANA), lupus syndrome, and Raynaud’s phenomenon.