Atenolol

Brand names: Atenolol Scopolamine, Atenolol and Chlorthalidone, TENORETIC, TENORMIN, Tenormin, Atenolol, ATENOLOL, Atenolol 29300-411, atenolol

Boxed warning

BOXED WARNING 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).

Warnings

No boxed warning. Contraindications: "sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure," and known hypersensitivity. Key warnings: beta-blockers can precipitate cardiac failure because "sympathetic stimulation is necessary in supporting circulatory function"; abrupt cessation has caused "severe exacerbation of angina and occurrence of myocardial infarction and ventricular arrhythmias"; "PATIENTS WITH BRONCHOSPASTIC DISEASE SHOULD, IN GENERAL, NOT RECEIVE BETA-BLOCKERS"; may mask hypoglycemia warning signs such as tachycardia; and "atenolol can cause fetal harm when administered to a pregnant woman."

Contraindications

CONTRAINDICATIONS Atenolol tablets are contraindicated in sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure. (See WARNINGS .) Atenolol tablets are contraindicated in those patients with a history of hypersensitivity to the atenolol or any of the drug product’s components.

Overdose

OVERDOSAGE Overdosage with atenolol has been reported with patients surviving acute doses as high as 5 g. One death was reported in a man who may have taken as much as 10 g acutely. The predominant symptoms reported following atenolol overdose are lethargy, disorder of respiratory drive, wheezing, sinus pause and bradycardia. Additionally, common effects associated with overdosage of any beta-adrenergic blocking agent and which might also be expected in atenolol overdose are congestive heart failure, hypotension, bronchospasm and/or hypoglycemia. Treatment of overdose should be directed to the removal of any unabsorbed drug by induced emesis, gastric lavage, or administration of activated charcoal. Atenolol can be removed from the general circulation by hemodialysis. Other treatment modalities should be employed at the physician's discretion and may include: BRADYCARDIA: Atropine intravenously. If there is no response to vagal blockade, give isoproterenol cautiously. In refractory cases, a transvenous cardiac pacemaker may be indicated. HEART BLOCK (SECOND OR THIRD DEGREE): Isoproterenol or transvenous cardiac pacemaker. CARDIAC FAILURE: Digitalize the patient and administer a diuretic. Glucagon has been reported to be useful. HYPOTENSION: Vasopressors such as dopamine or norepinephrine (levarterenol). Monitor blood pressure continuously. BRONCHOSPASM: A beta 2 stimulant such as isoproterenol or terbutaline and/or aminophylline. HYPOGLYCEMIA: Intravenous glucose. Based on the severity of symptoms, management may require intensive support care and facilities for applying cardiac and respiratory support.

Drug interactions

Drug Interactions Catecholamine-depleting drugs (e.g., reserpine) may have an additive effect when given with beta-blocking agents. Patients treated with atenolol plus a catecholamine depletor should therefore be closely observed for evidence of hypotension and/or marked bradycardia which may produce vertigo, syncope, or postural hypotension. Calcium channel blockers may also have an additive effect when given with atenolol (see WARNINGS ). Disopyramide is a Type I antiarrhythmic drug with potent negative inotropic and chronotropic effects. Disopyramide has been associated with severe bradycardia, asystole and heart failure when administered with beta-blockers. Amiodarone is an antiarrhythmic agent with negative chronotropic properties that may be additive to those seen with beta-blockers. Beta-blockers may exacerbate the rebound hypertension which can follow the withdrawal of clonidine. If the two drugs are coadministered, the beta-blocker should be withdrawn several days before the gradual withdrawal of clonidine. If replacing clonidine by beta-blocker therapy, the introduction of beta-blockers should be delayed for several days after clonidine administration has stopped. Concomitant use of prostaglandin synthase inhibiting drugs, e.g., indomethacin, may decrease the hypotensive effects of beta-blockers. Information on concurrent usage of atenolol and aspirin is limited. Data from several studies, i.e., TIMI-II, ISIS-2, currently do not suggest any clinical interaction between aspirin and beta-blockers in the acute myocardial infarction setting. 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, either accidental, diagnostic or therapeutic. Such patients may be unresponsive to the usual doses of epinephrine used to treat the allergic reaction. Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia.

Uses

Atenolol tablets are indicated for: - Treatment of hypertension, "to lower blood pressure" and reduce the risk of fatal and nonfatal cardiovascular events such as strokes and myocardial infarctions - Long-term management of patients with angina pectoris - Management of hemodynamically stable patients with definite or suspected acute myocardial infarction, "to reduce cardiovascular mortality."

Dosage forms & strengths

Tablet TABLET POWDER

ATENOLOL 100 mg CHLORTHALIDONE 25 mg ATENOLOL 25 mg SCOPOLAMINE HYDROBROMIDE .25 mg ATENOLOL 50 mg SCOPOLAMINE HYDROBROMIDE .5 mg Atenolol 100 mg Chlorthalidone 25 mg Atenolol 25 mg Atenolol 50 mg atenolol 25 mg atenolol 50 mg ATENOLOL 25 mg/1 ATENOLOL 50 mg/1 ATENOLOL 1 kg/kg ATENOLOL 100 mg/1 ATENOLOL 1 g/g ATENOLOL 50 kg/50kg

DOSAGE AND ADMINISTRATION Hypertension The initial dose of atenolol is 50 mg given as one tablet a day either alone or added to diuretic therapy. The full effect of this dose will usually be seen within one to two weeks. If an optimal response is not achieved, the dosage should be increased to atenolol 100 mg given as one tablet a day. Increasing the dosage beyond 100 mg a day is unlikely to produce any further benefit. Atenolol may be used alone or concomitantly with other antihypertensive agents including thiazide-type diuretics, hydralazine, prazosin, and alpha-methyldopa. Angina Pectoris The initial dose of atenolol is 50 mg given as one tablet a day. If an optimal response is not achieved within one week, the dosage should be increased to atenolol 100 mg given as one tablet a day. Some patients may require a dosage of 200 mg once a day for optimal effect. Twenty-four hour control with once daily dosing is achieved by giving doses larger than necessary to achieve an immediate maximum effect. The maximum early effect on exercise tolerance occurs with doses of 50 mg to 100 mg, but at these doses the effect at 24 hours is attenuated, averaging about 50% to 75% of that observed with once a day oral doses of 200 mg. Acute Myocardial Infarction In patients with definite or suspected acute myocardial infarction, treatment with atenolol I.V. injection should be initiated as soon as possible after the patient's arrival in the hospital and after eligibility is established. Such treatment should be initiated in a coronary care or similar unit immediately after the patient's hemodynamic condition has stabilized. Treatment should begin with the intravenous administration of 5 mg atenolol over 5 minutes followed by another 5 mg intravenous injection 10 minutes later. Atenolol I.V. injection should be administered under carefully controlled conditions including monitoring of blood pressure, heart rate, and electrocardiogram. Dilutions of atenolol I.V. injection in dextrose injection, sodium chloride injection, or sodium chloride and dextrose injection may be used. These admixtures are stable for 48 hours if they are not used immediately. In patients who tolerate the full intravenous dose (10 mg), atenolol tablets 50 mg should be initiated 10 minutes after the last intravenous dose followed by another 50 mg oral dose 12 hours later. Thereafter, atenolol can be given orally either 100 mg once daily or 50 mg twice a day for a further 6 to 9 days or until discharge from the hospital. If bradycardia or hypotension requiring treatment or any other untoward effects occur, atenolol should be discontinued. (See full prescribing information prior to initiating therapy with atenolol tablets.) Data from other beta-blocker trials suggest that if there is any question concerning the use of I.V. beta-blocker or clinical estimate that there is a contraindication, the I.V. beta-blocker may be eliminated and patients fulfilling the safety criteria may be given atenolol tablets 50 mg twice daily or 100 mg once a day for at least seven days (if the I.V. dosing is excluded). Although the demonstration of efficacy of atenolol is based entirely on data from the first seven postinfarction days, data from other beta-blocker trials suggest that treatment with beta-blockers that are effective in the postinfarction setting may be continued for one to three years if there are no contraindications. Atenolol is an additional treatment to standard coronary care unit therapy. Elderly Patients or Patients with Renal Impairment Atenolol is excreted by the kidneys; consequently dosage should be adjusted in cases of severe impairment of renal function. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. Evaluation of patients with hypertension or myocardial infarction should always include assessment of renal function. Atenolol excretion would be expected to decrease with advancing age. No significant accumulation of atenolol occurs until creatinine clearance falls below 35 mL/min/1.73 m 2 . Accumulation of atenolol and prolongation of its half-life were studied in subjects with creatinine clearance between 5 mL/min and 105 mL/min. Peak plasma levels were significantly increased in subjects with creatinine clearances below 30 mL/min. The following maximum oral dosages are recommended for elderly, renally-impaired patients and for patients with renal impairment due to other causes: Creatinine Clearance (mL/min/1.73 m 2 ) Atenolol Elimination Half-Life (h) Maximum Dosage 15-35 16-27 50 mg daily <15 >27 25 mg daily Some renally-impaired or elderly patients being treated for hypertension may require a lower starting dose of atenolol: 25 mg given as one tablet a day. If this 25 mg dose is used, assessment of efficacy must be made carefully. This should include measurement of blood pressure just prior to the next dose ("trough" blood pressure) to ensure that the treatment effect is present for a full 24 hours. Although a similar dosage reduction may be considered for elderly and/or renally-impaired patients being treated for indications other than hypertension, data are not available for these patient populations. Patients on hemodialysis should be given 25 mg or 50 mg after each dialysis; this should be done under hospital supervision as marked falls in blood pressure can occur. Cessation of Therapy in Patients with Angina Pectoris If withdrawal of atenolol therapy is planned, it should be achieved gradually and patients should be carefully observed and advised to limit physical activity to a minimum.