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Drug Details

Atenolol 25mg Tablets

• Drug Class Description
  Cardioselective b-blockers (beta- blockers).
• Generic Name
  Generic Atenolol is water soluble and therefore less likely to cross blood-brain barrier and cause nightmares and sleeping problems. Atenolol is cardioselective but NOT cardiospecific and so still may precipitate asthma.
• Presentation
  Tablet for oral use
• Description
  Atenolol 25mg Tablets or Totamol 25mg Tablets or Kentol 25mg Tablets
• Indications
  

  Atenolol is recommended for the treatment of hypertension, angina pectoris, cardiac dysrhythmia, and for early intervention in the acute phase of myocardial infarction.

• Adult Dosage
  

  Dosage

  Adults:

  Hypertension: Usually 50mg daily.

  Angina: Usually 100mg daily or 50mg twice daily.

  Dysrhythmias: Following control with intravenous atenolol, a suitable oral maintenance dosage is 50-100mg daily, given as a single dose.

  Myocardial Infarction: Following treatment with intravenous atenolol, oral atenolol 50mg may be given approximately 15 minutes later, provided no untoward effects occur from the intravenous dose. This should be followed by a further 50mg orally 12 hours after the intravenous dose and subsequent dosage maintained, after a further 12 hours, with 100mg daily. If bradycardia and/or hypotension requiring treatment, or any other untoward effects occur, atenolol should be discontinued.

  Renal impairment: The dose may need to be reduced.

  Hepatic dysfunction: The dose may need to be reduced.

   

   

• Child Dosage
  

  Children under 12 years of age:

  There are inadequate clinical data available on the use of atenolol in children and for this reason it is not recommended.

• Elderly Dosage
  

  Dosage requirements may be reduced, especially in patients with impaired renal function.

• Contra Indications
  

  Atenolol is contra-indicated in patients with a known hypersensitivity to atenolol, severe bradycardia, second degree or third degree heart block, uncontrolled heart failure, hypotension, severe peripheral vascular disease (including intermittent claudication), sick sinus syndrome, cardiogenic shock, phaeocromocytoma (without a concomitant alpha-blocker), metabolic acidosis.

  Although cardioselective beta-blockers may have less effect on lung function than non-selective beta-blockers, as with all beta-blockers these should be avoided in patients with asthma or a history of reversible obstructive airways disease or bronchospasm, unless there are compelling clinical reasons for their use.

• Special Precautions
  

  Care should be taken when using beta-blockers in patients with poor cardiac reserve. Myocardial contractility must be maintained and signs of failure controlled with digitalis and diuretics.

  Therapy should not be withdrawn abruptly, especially in patients with ischaemic heart disease, and replacement therapy should be considered to prevent exacerbation of angina pectoris, rebound hypertension, myocardial infarction, ventricular arrhythmias and sudden cardiac death. Treatment should not be discontinued abruptly in patients on long-term therapy, but should be discontinued over one to two weeks.

  If a beta-blocker is withdrawn prior to surgery it should be discontinued for at least 24 hours, if the patient is being anaesthetised. If beta blockers are not discontinued before anaesthesia, the anaesthetist should be made aware of the beta-blocker therapy. A drug such as atropine may be given to counter increases in vagal tone. Anaesthetics causing myocardial depression such as ether, halothane and enflurane should be avoide.

  Atenolol reduces heart rate. In instances when symptoms may be attributable to the slow heart rate, the dose should be reduced. Beta-blockers should be used with caution in first degree AV block.

  Beta-blockers may increase both the sensitivity towards allergens and seriousness of anaphylactic reactions and may also reduce the response to adrenaline. They may unmask myasthenia gravis or potentiate a myasthenic condition.

  Patients with psoriasis should only be given beta-blockers after careful consideration, as psoriasis may be aggravated.

  Atenolol should be used with caution in diabetics subject to frequent episodes of hypoglycaemia. Symptoms of hypoglycaemia and of hyperthyroidism may be masked.

  The product label will carry the warning " Do not take this medicine if there is a history of wheezing or asthma."

  If the use of atenolol in patients with asthma or a history of obstructive airways disease is unavoidable, the risk of inducing bronchospasm should be appreciated and appropriate precautions taken. If bronchospasm occurs, this will usually be reversed by commonly used bronchodilators such as salbutamol or isoprenaline.

  In patients with renal impairment or hepatic dysfunction, atenolol should be used with caution and reduction of dosage should be considered.

• Interactions
  

  Alcohol : Enhanced hypotensive effect

  Aldesleukin : Enhanced hypotensive effect.

  Alprostadil : Enhanced hypotensive effect.

  Amphetamines: Avoid concomitant use.

  Ampicillin: Reduces atenolol serum levels.

  Anaethetics: Enhanced hypotensive effect. Avoid anaesthetics which cause myocardial depression, e.g. ether, halothane and enflurane.

  Analgesics: Antihypertensive effects of beta-blockers may be impaired by non-steroidal anti-inflammatory drugs (NSAIDs), particularly indomethacin – avoid concomitant use.

  Antacids; Reduced absorption may occur if calcium or aluminium hydroxide is administered concurrently.

  Antiarrhythmics and other drugs affecting cardiac conduction; (eg, disopyramide, amiodarone, quinidine) additive negative inotropic effects on the heart, with increased risk of bradycardia, hypotension, ventricular fibrillation, heart block or asystole - avoid concomitant use.

  Anticholinesterase agents : Increased risk of bradycardia

  Antidepressants and antipsychotics: Phenothiazines and tricyclic antidepressants and tropisetron may increase the risk of ventricular arrhythmias. Enhanced hypotensive effect with monoamine oxidase inhibitors (MAOIs).

  Antidiabetics: Dosage of hypoglycaemic agents requirements may need to be increased. There may be an enhanced hypoglycaemic effect and masking of warning signs with concurrent administration of insulin and oral antidiabetic drugs. Hypoglycaemia is more likely in Type I than in Type II diabetics and may be associated with delayed recovery.

  Antihypertensives: including angiotensin-converting enzyme (ACE) inhibitors and angiotensin-II antagonists; enhanced hypotension; alpha-blockers; enhanced risk of first dose hypotension - avoid concomitant use. Cardiodepressant calcium channel blocking agents such as diltiazem, nifedipine and verapamil may induce negative inotropic effects such as severe hypotension, bradycardia, asystole and heart failure avoid concomitant use.

  Antimalarials: Risk of bradycardia increased with mefloquine.

  Anxiolytics and hypnotics : Enhanced hypotensive effect with benzodiazepines.

  Cardiac glycosides; Risk of marked bradycardia and AV block.

  Clonidine : Increased risk of hypertension on withdrawal – avoid concomitant use

  Ergot alkaloids; Increased peripheral vasoconstriction - avoid concomitant use.

  Moxisylyte: Increased risk of severe postural hypotension.

  Oestrogens and Progesterones; Oestrogens and combined oral contraceptives may antagonise the antihypertensive effect.

  Parasympathomimetics : Increased risk of bradycardia

  Sympathomimetics : Risk of severe hypertension and bradycardia with such agents as adrenaline, noradrenaline and ephedrine - avoid concomitant use. Beta-blockers may also reduce the response to adrenaline in the management of anaphylaxis.

  Theophylline : Atenolol antagonises bronchodilator effect: avoid concomitant use

  Ulcer healing drugs:Carbenoxolone may antagonise the hypotensive effect.

• Adverse Drug Reactions
  

  Cardiovascular: heart failure, heart block, bradycardia, hypotension, dizziness, peripheral vasoconstriction with coldness of the extremities (including exacerbation of intermittent claudication and Raynaud's phenomenon).

  Eye : visual disturbances including blurred vision, sore eyes, dry eyes (reversible on withdrawal; discontinuance of the drug should be considered if any such reaction is not otherwise explicable), conjunctivitis.

  Gastrointestinal: nausea, vomiting, diarrhoea, constipation and abdominal cramps, sclerosing peritonitis and retroperitoneal fibrosis.

  General: fatigue, headache, dry mouth, sleep disturbances of the type noted with other beta-blockers have been reported rarely. An increase in (A)nti (N)uclear (A)ntibodies has been seen: its clinical relevance is not clear.

  Haemopoietic: thrombocytopenia, eosinophilia and leucopenia including agranulocytosis.

  Hepatic : elevated liver enzymes and/or bilirubin

  Metabolic: Lupus-like syndrome. Hyperglycaemia or hypoglycaemia. Non-diabetic patients susceptible to hypoglycaemia include those on regular dialysis, and long term patients who are nutritionally compromised or have liver disease. Atenolol may increase serum triglyceride levels.

  Musculoskeletal, connective tissue and bone disorders: Myopathies including muscle cramps, arthralgia.

  Nervous system : paraesthesia, peripheral neuritis.

  Psychiatric : depression, psychosis, hallucinations, confusion, anxiety and nervousness.

  Respiratory : bronchospasm, pneumonitis, pulmonary fibrosis and pleurisy.

  Reproductive: impotence, Peyronie's disease;

  Skin: Purpura, pruritus, reversible alopecia, skin rashes (reversible on withdrawal; discontinuance of the drug should be considered if any such reaction is not otherwise explicable), psoriasiform rash or exacerbation of psoriasis.

  Withdrawal: Sudden cessation of therapy with a beta-blockercan cause angina, myocardial infarction, ventricular arrhythmias and sudden cardiac death.