Aveten

Aveten

atenolol

Manufacturer:

Avex

Distributor:

Apex
Full Prescribing Info
Contents
Atenolol.
Description
Each tablet contains Atenolol 50.00 mg.
Each tablet contains Atenolol 100.00 mg.
Action
Pharmacology: Pharmacodynamics: Atenolol is a beta- adrenoceptor blocking drug that is beta1- selective (i.e. acts preferentially on beta1- adrenergic receptors in the heart). Selectivity decreases with increasing dose.
Atenolol is without intrinsic sympathomimetic and membrane stabilizing activities and as with other beta-adrenoceptor blocking drugs, has negative inotropic effects (and is therefore contraindicated in uncontrolled heart failure).
As with other beta-adrenoceptor blocking drugs, the mode of action of atenolol in the treatment of hypertension is unclear. It is probably the action of atenolol in reducing cardiac rate and contractility that makes it effective in eliminating or reducing the symptoms of patients with angina.
It is unlikely that any additional ancillary properties possessed by S (-) atenolol, in comparison with the racemic mixture, will give rise to different therapeutic effects.
Atenolol is effective and well tolerated in most ethnic populations although the response may be less in black patients.
Atenolol is compatible with diuretics, other antihypertensive agents and antianginal agents.
Early intervention with atenolol in acute myocardial infarction reduces infarct size and decreases morbidity and mortality. Fewer patients with a threatened infarction progress to frank infarction; the incidence of ventricular arrhythmias is decreased and marked pain relief may result in reduced need of opiate analgesics. Early mortality is decreased. Atenolol is an additional treatment to standard coronary care.
Pharmacokinetics: Absorption of atenolol following oral dosing is consistent but incomplete ( approximately 40-50%) with peak plasma concentrations occurring 2-4 hours after dosing. The atenolol blood levels are consistent and subject to little variability. There is no significant hepatic metabolism of atenolol and more than 90% of that absorbed reaches the systemic circulation unaltered. The plasma half-life is about 6 hours but this may rise in severe renal impairment since the kidney is the major route of administration. Atenolol penetrates tissues poorly due to its low lipid solubility and its concentration in brain tissue is low. Plasma protein binding is low (approximately 3%).
Indications/Uses
AVETEN is indicated for the management of hypertension, management of angina pectoris, management of cardiac arrhythmias and management of myocardial infarction. Early intervention in the acute phase.
Dosage/Direction for Use
Mode of Administration: Oral administration.
Adults: Hypertension: One tablet daily. Most patients respond to 100mg daily given orally as a single dose. Some patients, however, will respond to 50mg given as a single daily dose. The effect will be fully established after one to two weeks. A further reduction in blood pressure may be achieved by combining AVETEN with other antihypertensive agents, for example co- administration with a diuretic.
Angina: Most patients with angina pectoris will respond to 100mg given orally once daily or 50mg given twice daily. It is unlikely that additional benefit will be gained by increasing the dose.
Arrhythmia: Having controlled the arrhythmias with intravenous injection, a suitable oral maintenance dosage is 50- 100mg daily, given as a single dose.
Myocardial Infarction: For patients suitable for treatment with intravenous beta-adrenoceptor blockade and presenting within 12 hours of the onset of chest pain, atenolol 5-10mg should be given by slow intravenous injection (1mg/ minute) followed by AVETEN 50mg orally about 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 then 12 hours later by 100mg orally to be given once daily. If bradycardia and/or hypotension requiring treatment, or any other untoward effects occur, AVETEN should be discontinued.
Elderly Patients: Dosage requirements may be reduced especially in patients with impaired renal function.
Children: There is no paediatric experience with AVETEN and for this reason it is not recommended for use in children.
Renal Failure: Since AVETEN is excreted via the kidneys, the dosage should be adjusted in cases of severe impairment of renal function.
No significant accumulation of AVETEN occurs in patients who have a creatinine clearance greater than 35ml/min/1.73m2 ( normal range is 100-150ml/min/1.73m2).
For patients with a creatinine clearance of 15-35ml/min/1.73m2 (equivalent to serum creatinine of 300-600 micromol/litre) the oral dose should be 50mg daily and the intravenous dose should be 10mg once every two days.
For patients with a creatinine clearance of < 15 ml/min/l.73m2 (equivalent to serum creatinine of >600 micromol/litre) the oral dose should be 25mg daily or 50mg on alternate days and the intravenous dose should be 10mg once every four days.
Patients on haemodialysis should be given 50mg orally after each dialysis; this should be done under hospital supervision as marked falls in blood pressure can occur.
Overdosage
The symptoms of overdosage may include bradycardia, hypotension, acute cardiac insufficiency and bronchospasm.
General treatment should include: close supervision, treatment in an intensive care ward, the use of gastric lavage, activated charcoal and a laxative to prevent absorption of any drug still present in the gastrointestinal tract, the use of plasma or plasma substitutes to treat hypotension and shock. The possible uses of haemodialysis or haemoperfusion may be considered.
Excessive bradycardia can be countered with atropine 1-2 mg intravenously and/or a cardiac pacemaker. If necessary, this may be followed by a bolus dose of glucagon 10mg intravenously. If required, this may be repeated or followed by an intravenous infusion of glucagon 1-10mg/hour depending on response. If no response to glucagon occurs or if glucagon is unavailable, a beta-adrenoceptor stimulant such as dobutamine 2.5 to 10 micrograms/kg/ minute by intravenous infusion may be given. Dobutamine, because of its positive inotropic effect could also be used to treat hypotension and acute cardiac insufficiency. It is likely that these doses would be inadequate to reverse the cardiac effects of beta-adrenoceptor blockade if a large overdose has been taken. The dose of dobutamine should therefore be increased if necessary to achieve the required response according to the clinical condition of the patient.
Bronchospasm can usually be reversed by bronchodilators.
Contraindications
AVETEN is contraindicated in patients with a known hypersensitivity to atenolol or any of the excipients.
AVETEN should not be administered in patients with bradycardia; cardiogenic shock; hypotension; metabolic acidosis; severe peripheral arterial circulatory disturbances; second or third degree heart block; sick sinus syndrome; untreated phaeochromocytoma; uncontrolled heart failure.
Special Precautions
ATENOLOL as with other beta- blockers: Should not be withdrawn abruptly. The dosage should be withdrawn gradually over a period of 7-14 days, to facilitate a reduction in beta-blocker dosage. Patients should be followed during withdrawal, especially those with ischaemic heart disease.
When a patient is scheduled for surgery, and a decision is made to discontinue beta- blocker therapy, this should be done at least 24 hours prior to the procedure. The risk- benefit assessment of stopping beta- blockade should be made for each patient. If treatment is continued, an anaesthetic with little negative inotropic activity should be selected to minimise the risk of myocardial depression. The patient may be protected against vagal reactions by intravenous administration of atropine.
Although contraindicated in uncontrolled heart failure , may be used in patients whose signs of heart failure have been controlled. Caution must be exercised in patients whose cardiac reserve is poor.
May increase the number and duration of angina attacks in patients with Prinzmetal's angina due to unopposed alpha- receptor mediated coronary artery vasoconstriction. ATENOLOL is a beta1- selective beta- blocker; consequently, its use may be considered although utmost caution must be exercised.
Although contraindicated in severe peripheral arterial circulatory disturbances, may also aggravate less severe peripheral arterial circulatory disturbances.
Due to its negative effect on conduction time, caution must be exercised if it is given to patients with first-degree heart block.
May mask the symptoms of hypoglycaemia, in particular, tachycardia.
May mask the signs of thyrotoxicosis.
Will reduce heart rate as a result of its pharmacological action. In the rare instances when a treated patient develops symptoms which may be attributable to a slow heart rate and the pulse rate drops to less than 50-55 bpm at rest, the dose should be reduced.
May cause a more severe reaction to a variety of allergens when given to patients with a history of anaphylactic reaction to such allergens. Such patients may be unresponsive to the usual doses of adrenaline ( epinephrine) used to treat the allergic reactions.
May cause a hypersensitivity reaction including angioedema and urticaria.
Should be used with caution in the elderly, starting with a lesser dose.
Since ATENOLOL is excreted via the kidneys, dosage should be reduced in patients with a creatinine clearance of below 35 ml/min/1.73m2.
Although cardioselective (beta1) 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 reversible obstructive airways disease, unless there are compelling clinical reasons for their use. Where such reasons exist, ATENOLOL may be used with caution. Occasionally, some increase in airways resistance may occur in asthmatic patients however, and this may usually be reversed by commonly used dosage of bronchodilators such as salbutamol or isoprenaline. The label and patient information leaflet for this product state the following warning: "If you have ever had asthma or wheezing, you should not take this medicine unless you have discussed these symptoms with the prescribing doctor".
As with other beta-blockers, in patients with a phaeochromocytoma, an alpha-blocker should be given concomitantly.
Use In Pregnancy & Lactation
Atenolol crosses the placental barrier and appears in the cord blood. No studies have been performed on the use of atenolol in the first trimester or in the third trimester under close supervision for the treatment of hypertension.
Administration of atenolol to pregnant women in the management of mild to moderate hypertension has been associated with intra-uterine growth retardation.
The use of atenolol in women who are, or may become pregnant requires that the anticipated benefit be weighed against the possible risks, particularly in the first and second trimesters, since beta-adrenoceptor blocking agents in general have been associated with a decrease in placental perfusion which may result in intra-uterine deaths, immature and premature deliveries. There is significant accumulation of atenolol in breast milk. Caution should be exercised when it is administered to a nursing woman.
Side Effects
Atenolol is well tolerated. In clinical studies, the undesired events reported are usually attributable to the pharmacological actions of atenolol.
Cardiovascular: Bradycardia; heart failure deterioration; postural hypotension which may be associated with syncope; cold extremities. In susceptible patients: precipitation of heart block; intermittent claudication, Raynaud's phenomenon.
CNS: Confusion; dizziness; headache; mood changes; nightmares; psychoses and hallucinations; sleep disturbances of the type noted with other beta-adrenoceptor blocking drugs.
Gastrointestinal: Dry mouth, gastrointestinal disturbances. Elevations of transaminase levels have been seen infrequently, rare cases of hepatic toxicity including intrahepatic cholestasis have been reported.
Haematological: Purpura; thrombocytopenia.
Integumentary: Alopecia; dry eyes, psoriasiform skin reactions; exacerbation of psoriasis; skin rashes.
Neurological: Paraesthesia.
Reproductive: Impotence.
Respiratory: Bronchospasm may occur in patients with bronchial asthma or a history of asthmatic complaints.
Special senses: Visual disturbances.
Others: Hypersensitivity reactions, including angioedema and urticaria; fatigue; an increase in ANA (Antinuclear Antibodies) has been observed, however, the clinical relevance of this is not clear.
Discontinuance of the drug should be considered if, according to clinical judgement, the well-being of the patient is adversely affected by any of the previously mentioned reactions.
Drug Interactions
Combined use of beta-blockers and calcium channel blockers with negative inotropic effects, e.g. verapamil and diltiazem, can lead to an exaggeration of these effects particularly in patients with impaired ventricular function and/or sinoatrial or atrioventricular conduction abnormalities. This may result in severe hypotension, bradycardia and cardiac failure. Neither the beta-blocker nor the calcium channel blocker should be administered intravenously within 48 hours of discontinuing the other. Concomitant therapy with dihydropyridines, e.g. nifedipine, may increase the risk of hypotension, and cardiac failure may occur in patients with latent cardiac insufficiency.
Digitalis glycosides, in association with beta- blockers, may increase atrioventricular conduction time.
Beta-blockers may exacerbate the rebound hypertension which can follow the withdrawal of clonidine. If the two drugs are co-administered, the beta- blocker should be withdrawn several days before discontinuing clonidine. If replacing clonidine by beta- blocker therapy, the introduction of beta- blockers should be delayed for several days after clonidine administration has stopped. Class I anti- arrhythmic drugs (e.g. disopyramide) and amiodarone may have a potentiating effect on atrial conduction time and induce negative inotropic effect.
Concomitant use of sympathomimetic agents, e.g. adrenaline (epinephrine), may counteract the effect of beta-blockers.
Concomitant use with insulin and oral antidiabetic drugs may lead to the intensification of the blood sugar lowering effects of these drugs. Symptoms of hypoglycaemia, particularly tachycardia, may be masked.
Concomitant use of prostaglandin synthetase-inhibiting drugs, e.g. ibuprofen and indometacin, may decrease the hypotensive effects of beta-blockers.
Caution must be exercised when using anaesthetic agents with ATENOLOL. The anaesthetist should be informed and the choice of anaesthetic should be an agent with as little negative inotropic activity as possible. Use of beta-blockers with anaesthetic drugs may result in attenuation of the reflex tachycardia and increase the risk of hypotension. Anaesthetic agents causing myocardial depression are best avoided.
Storage
Store in a dry place protected from light, below 30˚C.
MIMS Class
ATC Classification
C07AB03 - atenolol ; Belongs to the class of selective beta-blocking agents. Used in the treatment of cardiovascular diseases.
Presentation/Packing
Tab 50 mg (white, concave, round, 9mm diameter in size, scored on one side) x 3 x 10's. 100 mg (white, flat, round, 12mm diameter in size, scored on one side) x 3 x 10's.
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