Atenolol is a competitive,ß-1 selective adrenergic antagonist, similar to metoprolol. ß-adrenergic antagonists counter the effect of sympathomimetic neurotransmitters (i.e., catecholamines) by competing for receptor sites. Similar to metoprolol, it, in low doses, selectively blocks sympathetic stimulation mediated by ß-adrenergic receptors in the heart and vascular smooth muscle. It antagonizes ß1 receptors at doses 50 to 100 times less than those required to block ß2 receptors. This cardioselectivty is more pronounced at low doses and is lost at high doses. It lowers the blood pressure in hypertension and slows the heart rate.
. It is of Synthetic origin and belongs to Phenylcetamide. It belongs to Beta-1 adrenergic antagonist pharmacological group on the basis of mechanism of action and also classified in Beta Blocker, Beta1 Selective pharmacological group.The Molecular Weight of Atenolol is 266.30. It is weakly alkaline drug and Its pKa is 9.6.
Oral absorption of Atenolol is found to be 22% ±22. Volume of distribution is found to be 0.5-1.5 l/kg and plasma protien binding is <5%. and metabolism is reported via liver. Renal Excretion accounts for >90% and plasma half life is 6-8 hr.
Atenolol is known to interact with other drugs, the details of drug interactions is as follows:
Drug Details Severity Onset Management Adrenaline Atenolol may enhance the vasopressor effect of Adrenaline.Adrenaline used as a local anesthetic for dental procedures will not likely cause clinically relevant problems. Moderate Immediate Monitor increased pressor effects of Adrenaline if used in patients receiving Atenolol. The amount of Adrenaline in dental procedures as part of local anesthetic administration is not likely to be of clinical concern. Infiltrating larger volumes of local anesthetics for other surgical procedures (eg, >0.06 mg Adrenaline) may cause clinically-relevant problems. Aldesleukin Enhanced hypotensive effect when aldesleukin given with Beta-blockers (e.g atenolol). Alfuzosin Enhanced hypotensive effects when alpha-blockers (e.g Alfuzosin) given with beta-blockers (e.g Atenolol). Major Amiodarone (HCl) Increased myocardial depression when beta-blockers (e.g Atenolol) given with antiarrhythmics (e.g Amiodarone). Amlodipine (Besylate) Enhanced hypotensive effects when calcium-channel blockers (e.g Amlodipine) given with beta-blockers (e.g Atenolol) Clonidine (HCl) Atenolol may enhance the rebound hypertensive effect of Clonidine (HCl).This effect can occur when the Clonidine Hcl is abruptly withdrawn. Major Rapid If possible, withdraw Atenolol several days before slowly withdrawing. clonidine. Consider the use of labetalol in place of clonidine, as it has both alpha- and beta-blocking activity. Use a cardioselective beta-blocker (such should pose less risk than nonselective agents). Monitor closely for acute rise in blood pressure. Diazepam Atenolol may increase the serum concentration of Diazepam. Minor No action required. Digoxin Atenolol may enhance the bradycardic effect of digoxin. Moderate Monitor bradycardia if these two agents are used concomitantly. Diltiazem (HCl) Diltiazem may enhance the hypotensive effect of Atenolol. Bradycardia and signs of heart failure have also been reported.Diltiazem may decrease the metabolism, via CYP isoenzymes, of Atenolol. Moderate Though usually safe and effective during concomitant use, monitor bradycardia, hypotension, or signs of heart failure during concomitant use of Atenolol and Diltiazem. phthalmic beta-blockers are of little concern. Disopyramide Both drugs produce additive effect on heart results in reduced cardiac output, hypotension and bradycardia. Atenolol also decreases the clearence of disopyramide.Intravenous administration of these agents may exacerbate the risk of adverse effects. Moderate Closely monitor for cardiac output, blood pressure, heart rate and ECG. Flurbiprofen Antihypertensive effect of Atenolol may decrease if use with Flurbiprofen sodium. Indomethacin Indomethacin alters the antihypertensive effects of atenolol by inhibiting synthesis of renal prostaglandins results in unopposed pressor activity producing hypertension. Moderate Closely monitor the patient for changed antihypertensive response whenever therapy with indomethacin starts, stopped or modified. Lacidipine Enhanced hypotensive effects when beta-blockers (e.g Atenolol) given with calcium-channel blockers (e.g Lacidipine). Metformin (HCl) Atenolol enhance the hypoglycemic effect of metformin. Moderate Monitoring of patient blood glucose level should be done when these drugs are coadministered. Naphazoline Concurrent use may result in interaction. Dosage adjustment or special monitoring during concurrent use is necessary. Nifedipine Combined use of atenolol with nifedipine decrease the rate, conduction and contractility of heart particularly in patients of ventricular or conduction abnormalities.by decreasing peripheral vascular resistance. Moderate Dosage regimen should be adjusted accordingly. Closely monitor the hemodynamic effect and tolerance of patient. Prazosin Enhanced hypotensive effects when alpha-blockers (e.g Prazosin) given with beta-blockers (e.g Atenolol), also increased risk of first-dose hypotension. Major Thioridazine (HCl) Both agents act additively and produce hypotensive and central nervous system depressant effect. Moderate Closely monitor for hypotension and prolonged CNS depression. Patient should notify to physician about excessive side effects. Verapamil (HCl) Verapamil may enhance the hypotensive effect of Atenolol.Bradycardia and signs of heart failure have also been reported.Verapamil may decrease the metabolism, via CYP isoenzymes, of Atenolol. Moderate Though usually safe and effective during concomitant use, monitor bradycardia, hypotension, or signs of heart failure during concomitant use of Atenolol and Verapamil. Ophthalmic beta-blockers are of little concern. It is recommended that atenolol should not be administered IV within 24 hourrs of discontinuing Verapamil.
These interactions are sometimes beneficial and sometimes may pose threats to life. Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.
Interference in Pathology
No data regarding the pathological interferences produced by Atenolol is available.
The severe or irreversible adverse effects of Atenolol, which give rise to further complications include Hypotension, Bronchospasm, Impotence, AV-block, Agranulocytosis, Hyperglycemia, Sinus bradycardia, Oculomucocutaneous syndrome.
Atenolol produces potentially life-threatening effects which include Heart failure. which are responsible for the discontinuation of Atenolol therapy.
The signs and symptoms that are produced after the acute overdosage of Atenolol include Bradycardia, Convulsions, Coma, Ventricular asystole.
The symptomatic adverse reactions produced by Atenolol are more or less tolerable and if they become severe, they can be treated symptomatically, these include Dizziness, Fatigue, Alopecia, Diarrhea, Dyspnea, Cold extremities, Constipation, Insomnia, Pruritus, Impotence, Depression, Blood dyscrasias, Exfoliative dermatitis, Paresthesias, Hyperpigmentation, Wheezing, Vivid dreams, Xerosis.
Atenolol's dosage details are as follows:
2.5 mg 2.5 (2.5) As recommended. IV At a rate of 1 mg/min 150 mcg/kg 150 (150) As recommended. IV infusion Over 20 minutes. Maintenance dose 50-100 mg.
50 to 200 mg 120 (125) 24 hourly PO
Paedriatic Dosage ( 20 Kg. )
1 to 2 mg/kg 1.5 (1.5) 24 hourly Oral -
1 to 2 mg/kg 1.5 (1.5) 24 hourly Slow IV -
Neonatal Dosage ( 3 Kg. )
1 to 2 mg/kg 1.5 (1.5) 24 hourly oral Gradually increase the dose
1 to 2 mg/kg 1.5 (1.5) 24 hourly Slow intravenous Gradually increase the dose
High Risk Groups
Drug should not be given to Paediatrics, patients suffering from Kidney dysfunction, and Neonates.
If prescribing authority justifies the benefits of the drug against the possible damages he/she should reevaluate them and consult the reference material and previous studies.
Warning / Precautions
Atenolol should be used with caution in patients with poorly controlled diabetes mellitus particularly brittle diabetes, in patients with liver or kidney impairments, in hyperthyroidism or thyrotoxicosis because the drug can mask the tachycardia that occur in this condition. Abrupt withdrawal of atenolol in hyperthyroidism patient can precipitate a thyroid storm. Avoid abrupt withdrawal in angina patients. Use with caution during pregnancy.
Store at room temperature, Below 30°C or in refrigerator. Do not Freeze. Protect from Sunlight.
Store in a well closed container, Below 40°C. Protect from Sunlight and Moisture.
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