Tenormin (atenolol)
Last reviewed · Source: First Databank (FDB) drug data
Overview
Atenolol is a beta1-selective adrenergic blocking agent (beta-blocker).
Atenolol is a beta1-selective adrenergic blocking agent (beta-blocker) without membrane stabilizing or intrinsic sympathomimetic (partial agonist) activities. Lower doses of atenolol selectively inhibit cardiac and lipolytic beta1-adrenergic receptors while having less effect on the beta2-adrenergic receptors of bronchial and vascular smooth muscle. At higher doses, this selectivity of atenolol for beta1-adrenergic receptors usually diminishes, and the drug will competitively block beta1- and beta2-adrenergic receptors.
By inhibiting myocardial beta1-adrenergic receptors, atenolol produces negative chronotropic and inotropic activity. The negative chronotropic action of atenolol on the sinoatrial (SA) node results in a decrease in the rate of SA node discharge and an increase in recovery time, thereby decreasing resting and exercise-stimulated heart rate and reflex orthostatic tachycardia. Atenolol also slows conduction in the atrioventricular (AV) node.
Although stroke volume may be increased moderately by about 10% at rest and during exercise, atenolol usually reduces cardiac output. The decrease in myocardial contractility and heart rate, as well as the reduction in blood pressure, produced by atenolol generally lead to a reduction in myocardial oxygen consumption which accounts for the effectiveness of the drug in chronic stable angina pectoris; however, atenolol can increase oxygen requirements by increasing left ventricular fiber length and end-diastolic pressure, particularly in patients with cardiac failure.
Because of its beta1-receptor selectivity, atenolol increases airway resistance (as measured by decreasing forced expiratory volume in 1 second) to a smaller extent than nonselective beta-blockers (e.g., propranolol) and does not inhibit bronchodilatory response to isoproterenol.
Atenolol is rapidly but incompletely absorbed from the GI tract. Only about 50% of an oral dose of atenolol is absorbed; peak plasma concentrations are achieved 2-4 hours after oral administration. An approximately fourfold interindividual variation in plasma concentrations attained has been reported.
In geriatric patients, plasma concentrations are increased. Peak plasma atenolol concentrations are achieved within 5 minutes following direct IV injection of the drug (no longer available in the US), and decline rapidly during an initial distribution phase; after the first 7 hours, plasma concentrations reportedly decline with an elimination half-life similar to that of orally administered drug.
The effect of atenolol on heart rate usually has an onset of 1 hour, peaks at 2-4 hours, and persists for 24 hours following oral administration of the drug. Following IV administration of a single 10-mg dose, the effect on heart rate usually peaks within 5 minutes and generally is negligible by 12 hours after the dose. The antihypertensive and beta-adrenergic blocking effect of a single 50- to 100-mg oral dose usually persists for 24 hours.
Atenolol's effect on heart rate, but not on blood pressure, correlates linearly with plasma atenolol concentrations.
Approximately 6-16% of atenolol is bound to plasma protein.
Atenolol readily crosses the placenta and has been detected in cord blood. During continuous administration, fetal serum concentrations of the drug are probably equivalent to those in maternal serum. Atenolol is distributed into milk; peak milk concentrations of the drug are higher than peak serum concentrations after an individual dose, and the area under the milk concentration-time curve (AUC) is substantially greater than that of the serum AUC in lactating women receiving the drug continuously.
In patients with normal renal function, atenolol has a plasma half-life (t1/2) of 6-7 hours. Children with normal renal function may exhibit a shorter elimination half-life. In one study in children 5-16 (mean: 8.9) years of age with arrhythmias and normal renal and hepatic function, the terminal elimination half-life averaged 4.6 hours.
The plasma half-life (t1/2) of atenolol is markedly prolonged in geriatric patients compared with that in younger patients. Plasma t1/2 of the drug increases to 16-27 hours in patients with creatinine clearances of 15-35 mL/minute per 1.73 m2 and exceeds 27 hours in patients with creatinine clearances less than 15 mL/minute per 1.73 m2. Little or no metabolism of atenolol occurs in the liver; pharmacokinetic parameters were unchanged in a small number patients with chronic liver disease and normal renal function.
Approximately 50% of an oral dose of the drug is excreted in urine unchanged; the remainder is excreted unchanged in feces. Atenolol was found to be dialyzable in a small number of patients receiving high-flux maintenance hemodialysis.
In geriatric patients, total plasma clearance of atenolol is reduced by about 50% compared with that in younger patients, resulting in higher plasma concentrations of the drug. The decreased clearance in geriatric adults may be related to decreased renal function in this age group.
USES: This medication is used to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. It is also used to treat chest pain (angina) and to improve survival after a heart attack.
Atenolol belongs to a class of drugs known as beta blockers. It works by blocking the action of certain natural substances in your body, such as epinephrine, on the heart and blood vessels. This effect lowers the heart rate, blood pressure, and strain on the heart.
Generic name: atenolol
Pronunciation: (a-TEN-oh-lol)
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
Today’s intelligence on Tenormin
Indications
The following indications are listed for Tenormin:
- Acute Myocardial Infarction
- Hypertension
- Prevention Of Anginal Pain Associated With Coronary Artery Disease
Also known as: Acute Mi, Cardiac Infarction, Elevated Blood Pressure, Essential Hypertension, Hyperpiesia, Hyperpiesis, Hypertensive Disorder, Myocardial Infarct, Prevention Of Anginal Pain Associated With Cad, Systemic Arterial Hypertension.
Dosing
Dosage of atenolol must be individualized and adjusted according to the patient's response and tolerance. If atenolol therapy is discontinued, dosage of the drug should be reduced gradually; patients with angina should be advised to limit physical activity.
Atenolol is administered orally; the drug also has been administered by IV injection, however a parenteral preparation no longer is commercially available in the US.
Atenolol is also commercially available in fixed combination with chlorthalidone. Consult the prescribing information for additional information on this combination product.
No dosing information is available for this tab.
No dosing information is available for this tab.
Drug interactions
Atenolol undergoes little or no metabolism by the liver.
There are no contraindication interactions for this drug.
There are no severe interactions for this drug.
There are no moderate interactions for this drug.
Contraindications
*Sinus bradycardia.
*AV block greater than first degree.
*Cardiogenic shock.
*Overt or decompensated cardiac failure not promptly and effectively controlled by IV furosemide 80 mg or equivalent therapy.
*Known hypersensitivity to atenolol or any ingredient in the formulation.
There are no contraindication contraindications for this drug.
There are no severe contraindications for this drug.
There are no moderate contraindications for this drug.
Adverse reactions
The most common adverse reactions (>10%) reported with atenolol in clinical studies were cold extremities, dizziness, tiredness, and depression.
There are no severe adverse reactions for this drug.
There are no less severe adverse reactions for this drug.
Precautions
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Safety and efficacy of atenolol in pediatric patients have not been established; however, some experts have suggested pediatric dosages for hypertension based on clinical experience.
Atenolol has been shown to cause a dose-related increase in embryonal and fetal resorptions in rats when given at dosages 25 or more times the maximum human antihypertensive dosage; similar effects were not observed in rabbits receiving atenolol dosages up to 12.5 times the maximum human antihypertensive dosage.
Atenolol crosses the placenta and has been detected in cord blood in humans. Atenolol can cause fetal harm when administered to pregnant women. There are no studies on use of the drug during the first trimester of pregnancy and the possibility of fetal injury cannot be excluded. Atenolol therapy initiated in the second trimester of pregnancy has been associated with birth of infants who were small for gestational age. Intrauterine growth retardation, especially when administered earlier in gestational age and/or for a longer duration, has occurred. Although some beta-blockers (e.g., labetalol, metoprolol, propranolol) may be considered for the management of hypertension, atrial fibrillation, or other supraventricular arrhythmias during pregnancy, experts generally recommend avoiding the use of atenolol. Neonates born to mothers who receive atenolol at parturition may be at risk for developing hypoglycemia and bradycardia; caution is recommended if atenolol is administered during pregnancy. If atenolol is administered during pregnancy or if the patient becomes pregnant while receiving the drug, the patient should be informed of the potential fetal harm.
Atenolol is distributed into milk. The drug distributes into milk in concentrations 1.5-6.8 times those in maternal serum. In at least one infant, potentially toxic serum atenolol concentrations (2 mcg/mL) have been reported 48 hours after discontinuance of breast-feeding. In a small number of mother-infant pairs studied, relative infant dose (RID) values varied; RID may decrease with increasing postpartum age. Neonates of mothers who receive atenolol during breast-feeding may be at risk of developing hypoglycemia and adverse beta-adrenergic effects (e.g., bradycardia). Therefore, the manufacturer states that atenolol should be used cautiously in nursing women. Because clearance of the drug may be substantially impaired, premature neonates and infants with impaired renal function may be at increased risk of developing adverse effects from ingested atenolol during breast-feeding.
If a woman receiving atenolol breast-feeds, the infant should be monitored closely for potential systemic effects of the drug. Alternatively, beta-blockers that distribute less extensively into milk (e.g., propranolol) can be considered, although caution still must be exercised.
Consider the greater frequency of decreased hepatic, renal, and/or cardiac function and of concomitant disease and drug therapy in geriatric patients. For the management of hypertension in geriatric patients, initiation of oral atenolol therapy at 25 mg daily may be necessary because of age-related decreases in renal function; if this dosage is employed, measurement of blood pressure just prior to a dose is recommended to ensure persistence of adequate blood pressure reduction. Although similar, low-dose initial therapy may be warranted for indications other than hypertension, data currently are not available.
Clinical studies of atenolol (used for angina pectoris associated with coronary atherosclerosis or hypertension) and of atenolol in fixed combination with chlorthalidone (used for hypertension) did not include sufficient numbers of patients 65 years of age and older to determine whether geriatric patients respond differently than younger adults. In addition, in a large clinical study (ISIS-1) evaluating atenolol in 8037 patients for the management of suspected acute MI, 2644 patients (about 33%) were 65 years of age or older, and there were no overall differences in safety or efficacy observed between geriatric individuals and younger adults; however, geriatric patients with systolic blood pressure below 120 mmHg seemed less likely to benefit from atenolol therapy. Although other clinical experience has not revealed age-related differences in response to the drug, care should be taken in dosage selection of atenolol. Because of greater frequency of decreased hepatic, renal, and/or cardiac function and of concomitant disease and drug therapy in geriatric patients, the manufacturer suggests that patients in this age group receive initial dosages of the drug in the low end of the usual range. The manufacturer states that evaluation of geriatric patients with hypertension or MI always should include assessment of renal function.
ICD codes
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Last reviewed · Source: First Databank (FDB) drug data
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