RiteMED Atenolol Special Precautions

Cardiac failure: Beta-blockade carries the potential hazard of depressing myocardial contractility and precipitating more severe heart failure. Cautiously administer atenolol in patients with congestive heart failure controlled by digitalis and/or diuretics, since both digitalis and atenolol slow AV conduction.
Cardiac failure which is not promptly and effectively controlled by IV furosemide 80 mg or equivalent therapy is a contraindication to beta-blocker treatment in patients with acute myocardial infarction.
In patients without a history of cardiac failure: Continued depression of the myocardium with beta-blockers over a period of time may, in some cases, lead to cardiac failure. At the first sign or symptom of impending cardiac failure, treat patients appropriately according to currently recommended guidelines and closely observe their response. Discontinue atenolol if cardiac failure continues despite adequate treatment.
Concomitant use of calcium channel blockers: (see Interactions).
Bronchospastic diseases: In general, patients with bronchospastic diseases should not receive beta-blockers. Because of its relative beta1 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 beta1 selectivity is not absolute, the lowest possible atenolol dose should be used with therapy initiated at 50 mg and a beta2-stimulating agent (bronchodilator) should be made available. If dosage must be increased, consider dividing the dose to achieve lower peak blood levels.
Anesthesia and major surgery: During anesthesia and post-operative period, beta-blockade may have beneficial effects in decreasing the incidence of arrhythmias and myocardial ischemia. It is recommended that maintenance of beta-blockade be continued peri-operatively. The anesthetist must be aware of beta-blockade because of the potential for interactions with other medication, resulting in severe bradyarrhythmias and hypotension, decreased reflex ability to compensate for blood loss, hypovolemia and regional sympathetic blockade, and increased propensity for vagal-induced bradycardia. Incidents of protracted severe hypotension or difficulty restoring normal cardiac rhythm during anesthesia have been observed. Modern inhalational anesthetics are generally well tolerated, although older agents (e.g., ether, cyclopropane, methoxyflurane, trichloroethylene) are sometimes associated with severe circulatory depression in the presence of beta-blockade.
Diabetes and hypoglycemia: Beta-blockers affect glucose metabolism and may mask some important premonitory signs of acute hypoglycemia (i.e., tachycardia).
In patients with insulin or non-insulin dependent diabetes, particularly labile diabetes, or with a history of spontaneous hypoglycemia, beta-blockade may result in the loss of diabetic control and delayed recovery from hypoglycemia. The dose of insulin or oral hypoglycemic agent may need adjustment.
Thyrotoxicosis: The effect of beta-blockers on thyroid hormone metabolism may result in increased serum free thyroxine (T4) levels. In the absence of any signs or symptoms of hyperthyroidism, additional investigation is necessary before a diagnosis of thyrotoxicosis can be made. Abrupt withdrawal of beta blockade might precipitate a thyroid storm; thus, closely monitor patients suspected of developing thyrotoxicosis from whom atenolol is to be withdrawn.
Pheochromocytoma: In patients with this condition, an alpha-blocking agent (e.g, phentolamine/phenoxybenzamine) must be administered before a beta-blocker to avoid exacerbation of hypertension.
Prinzmetal angina: There is a risk of exacerbating coronary artery spasm if patients with Prinzmetal or variant angina are treated with beta-blocker. If this treatment is essential, it should be undertaken in an intensive care unit.
Peripheral circulation: Beta blockade may impair the peripheral circulation and exacerbate the symptoms of peripheral vascular disease.
First degree heart block: Use with caution in patients with first degree heart block due to its negative effect on conduction time.
Renal disease: Hemodynamic changes following beta-blockade may impair renal function further in patients with severe renal disease.
Use in myocardial infarction: Patients with the following conditions are not suitable for atenolol treatment: Systolic blood pressure <120 mmHg (systolic blood pressure <120 mmHg in combination with a heart rate >90 beats/min has a particularly poor prognosis).
First degree AV block. After atenolol use, an increased incidence of cardiogenic shock (and need for inotropes), complete heart block and cardiovascular death has been observed in these patients.
Patients with atrial fibrillation after myocardial infarction, who were treated with atenolol, also had increased cardiovascular mortality compared with those not treated with atenolol. Patients may be digitalized before therapy with atenolol is resumed.
Bradycardia: Reduce dosage if patients treated with atenolol develop symptoms which may be attributable to slow heart rate.
Other metabolic effects: Beta-adrenoreceptors are involved in the regulation of lipid as well as carbohydrate metabolism. Some medicines affect the lipid profile adversely although the long-term clinical significance of this change is unknown and the effect appears to be less for medicines with intrinsic sympathomimetic activity.
History of anaphylactic reaction: While taking beta-blockers, patients with a history of anaphylactic reaction to a variety of allergens may have a more severe reaction on repeated challenge. Such patients may be unresponsive to the usual doses of epinephrine used to treat the allergic reactions.
Allergic conditions: Allergy may be exaggerated by beta-blockade (e.g., allergic rhinitis during pollen season and allergic reactions to bee and wasp stings). Avoid beta-blockers if there is a risk of bronchospasm.
Eye and skin reactions: Various skin rashes and conjunctival xerosis have been associated with beta-blockers. Cross-reactions may occur between beta-blockers; thus, substitutions within the group may not necessarily preclude occurrence of symptoms.
Use in Children: There is no experience with atenolol in children.
Use in the Elderly: Dosage requirements may be reduced particularly in patients with renal impairment (see Dosage & Administration).