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Tenormin

Reals Pharmaceuticals Limited
Plot 1 Junaid Dosunmu Street,Central Business District, Alausa, P.0. Box 3560 Ikeja, Lagos, Nigeria.
Email: reals@realsgroup.com
Tel: + 234-1-774-1205
Fax: +234-1-263-0919
Website: http://realsgroup.com

Brand Name

Tenormin

Manufacturer

AstraZeneca, Silk Court, Silk Road Business Park, Macclesfield, Cheshire SK10 2NA, England.


Therapeutic Class

Beta-blockers

Dosage Form, Composition & NAFDAC Registration Number (NRN)

Tablets (NRN: 04-0366): Atenolol PhEur 50 mg, 100 mg

Pack Size:

Pharmacology

Tenormin is a beta-blocker which is beta1-selective (i.e. acts preferentially on beta1-adrenergic receptors in the heart). It is without intrinsic sympathomimetic and membrane stabilising activities. Human studies indicate that it crosses the blood brain barrier only to a negligible extent. As with other beta-blockers, its mode of action in the treatment of hypertension is unclear. It is probably the action of Tenormin in reducing cardiac rate and contractility which makes it effective in eliminating or reducing the symptoms of patients with angina.

Early intervention with Tenormin 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.

Tenormin is an additional treatment to standard coronary care. Following intravenous administration the blood levels of atenolol decay tri-exponentially with an elimination half-life of about 6 hours. Throughout the IV dose range of 5-10 mg the blood level profile obeys linear pharmacokinetics and beta-blockade is still measurable 24 hours after a 10 mg intravenous dose. Absorption of atenolol following oral dosing is consistent but incomplete (approximately 40-50%) with peak plasma concentrations occurring 2-4 hours after dosing.

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 elimination 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

Control of hypertension;

Management of angina pectoris;

Control of cardiac arrhythmias;

Treatment of myocardial infarction.

Early intervention and late intervention after myocardial infarction.

Contra-indications

Presence of second or third degree heart block. Patients with cardiogenic shock.

Precautions/Warnings

Special care should be taken with patients whose cardiac reserve is poor. Beta-blockers should be avoided in overt heart failure. However, they may be used in patients whose signs of failure have been controlled. One of the pharmacological actions of beta-blockers is to reduce heart rate. In the rare instance when symptoms may be attributable to the slow heart rate, the dose may be reduced. Tenormin modifies the tachycardia of hypoglycaemia.

Tenormin may be used with caution in patients with chronic obstructive airways disease. However, some increase in airways resistance may occur occasionally in asthmatic patients. This can usually be reversed by commonly used dosage of bronchodilators such as salbutamol or isoprenaline. In patients suffering from ischaemic heart disease, as with other beta-blockers, treatment should not be discontinued abruptly. Tenormin may aggravate peripheral arterial circulatory disorders.

While taking beta-blockers, patients with a history of anaphylactic reaction to a variety of allergen may have a more severe reaction on repeated challenge. Such patients may be unresponsive to the usual doses of adrenaline used to treat the allergic reactions.

Anaesthesia: Care should be taken when using anaesthetic agents with Tenormin. The anaesthetist should be informed and the choice of anaesthetic should be the agent with as little negative inotropic activity as possible.

Pregnancy: Tenormin crosses the placental barrier and appears in the cord blood. No studies have been performed on the use of Tenormin in the first trimester and the possibility of foetal injury cannot be excluded. Tenormin has been used under close supervision for the treatment of hypertension in the third trimester.

Administration of Tenormin for longer periods to pregnant women in the management of mild to moderate hypertension has been associated with intrauterine growth retardation. The use of Tenormin 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.

Lactation: There is significant accumulation of Tenormin in breast milk. Caution should be exercised when Tenormin is administered to a nursing woman.

Effect on ability to drive or operate machinery: Unlikely to cause any impairment of the ability of patients to drive or operate machinery.

Interactions

Care should be taken in prescribing a beta-blocker with Class I anti-arrythmic agents such as disopyramide. Combined use of beta-blockers and calcium channel blockers with negative inotropic effects e.g. verapamil, diltiazem can lead to an exaggeration of these effects, particularly in patients with impaired ventricular function and/or SA or AV 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.

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.

Adverse Effects

Minor side effects include cold extremities, fatigue, gastro-intestinal disturbance and, in isolated cases, bradycardia. Headache, mood changes, dizziness and deterioration in heart failure may occasionally occur. Sleep disturbances of the type noted with other beta-blockers, postural hypotension which may be associated with syncope alopecia, thrombocytopenia, purpura, psoriasiform skin reactions, exacerbation of psoriasis, visual disturbances, psychoses, hallucinations and precipitation of heart block in susceptible patients have rarely been reported.

There have been reports of skin rashes and/or dry eye associated with the use of beta-blockers. The reported incidence is small and in most cases the symptoms have cleared when treatment was withdrawn. Discontinuance of the drug should be considered if any such reaction is not otherwise explicable.

Dosage & Administration

Adults: Hypertension: Most patients respond to 50-100 mg daily given orally as a singledose. The effect will be fully established after one to two weeks. A further reduction in blood pressure may be achieved by combining Tenormin with other antihypertensive agents. For example, co-administration of Tenormin with a diuretic, such as chlorthalidone, provides a highly effective and convenient antihypertensive therapy.

Angina: Most patients with angina pectoris will respond to 100 mg daily given orally as a single or divided dose. It is unlikely that additional benefit will be gained by increasing the dose.

Arrhythmias: A suitable initial dose of Tenormin is 2.5 mg (5 mL) injected intravenously over a 2.5 minute period (i.e. 1 mg/minute). This may be repeated at 5 minute intervals until a response is observed up to a maximum dosage of 10 mg. If Tenormin is given by infusion, 0.15 mg/kg body weight may be administered over a 20 minute period. If required, the injection or infusion may be repeated every 12 hours. Having controlled the arrhythmias with intravenous Tenormin, a suitable oral maintenance dosage is 50-100 mg daily, given as a single dose.

Myocardial infarction:- Early intervention after acute myocardial infarction: Reduction of infarct size, incidence of ventricular arrhythmias, morbidity, pain, need for opiate analgesics and early mortality: For patients suitable for treatment with intravenous beta-blockade and presenting within 12 hours of the onset of chest pain, Tenormin, 5-10 mg should be given immediately by slow intravenous injection (1 mg/minute) followed by Tenormin, 50 mg orally about 15 minutes later provided no untoward effects occur from the intravenous dose. This should be followed by 50 mg orally 12 hours after the intravenous dose and then 12 hours later by 100 mg orally to be given once daily. If bradycardia and/or hypotension requiring treatment, or any other untoward effects occur, Tenormin should be discontinued.

Late intervention after acute myocardial infarction: For patients who present some days after suffering an acute myocardial infarction an oral dose of Tenormin (100 mg daily) is recommended for long -term prophylaxis of myocardial infarction.

Children: There is no paediatric experience with Tenormin and for this reason it is not recommended for use in children.

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

Renal Failure: Since Tenormin is excreted via the kidneys dosage should be adjusted in cases of severe impairment of renal function. No significant accumulation of Tenormin occurs in patients who have a creatinine clearance greater than 35 mL/min/1.73 m2 (normal range is 100-150 mL/min/1.73 m2). For patients with a creatinine clearance of 15-35 mL/min/1.73 m2 (equivalent to serum creatinine of 300-600 mmol/litre) the oral dose should be 50 mg daily and the intravenous dose should be 10 mg once every two days. For patients with a creatinine clearance of 2 (equivalent to serum creatinine of >600 mmol/litre) the oral dose should be 25 mg daily or 50 mg on alternate days and the intravenous dose should be 10 mg once every four days.

Patients on haemodialysis should be given 50 mg orally after each dialysis; this should be done under hospital supervision as marked falls in blood pressure can occur.

Adults: Hypertension: Most patients respond to 50-100 mg daily given orally as a singledose. The effect will be fully established after one to two weeks. A further reduction in blood pressure may be achieved by combining Tenormin with other antihypertensive agents. For example, co-administration of Tenormin with a diuretic, such as chlorthalidone, provides a highly effective and convenient antihypertensive therapy.

Angina: Most patients with angina pectoris will respond to 100 mg daily given orally as a single or divided dose. It is unlikely that additional benefit will be gained by increasing the dose.

Arrhythmias: A suitable initial dose of Tenormin is 2.5 mg (5 ml) injected intravenously over a 2.5 minute period (i.e. 1 mg/minute). This may be repeated at 5 minute intervals until a response is observed up to a maximum dosage of 10 mg. If Tenormin is given by infusion, 0.15 mg/kg body weight may be administered over a 20 minute period. If required, the injection or infusion may be repeated every 12 hours. Having controlled the arrhythmias with intravenous Tenormin, a suitable oral maintenance dosage is 50-100 mg daily, given as a single dose.

Myocardial infarction:- Early intervention after acute myocardial infarction: Reduction of infarct size, incidence of ventricular arrhythmias, morbidity, pain, need for opiate analgesics and early mortality: For patients suitable for treatment with intravenous beta-blockade and presenting within 12 hours of the onset of chest pain, Tenormin, 5-10 mg should be given immediately by slow intravenous injection (1 mg/minute) followed by Tenormin, 50 mg orally about 15 minutes later provided no untoward effects occur from the intravenous dose. This should be followed by 50 mg orally 12 hours after the intravenous dose and then 12 hours later by 100 mg orally to be given once daily. If bradycardia and/or hypotension requiring treatment, or any other untoward effects occur, Tenormin should be discontinued.

Late intervention after acute myocardial infarction: For patients who present some days after suffering an acute myocardial infarction an oral dose of Tenormin (100 mg daily) is recommended for long -term prophylaxis of myocardial infarction.

Children: There is no paediatric experience with Tenormin and for this reason it is not recommended for use in children.

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

Renal Failure: Since Tenormin is excreted via the kidneys dosage should be adjusted in cases of severe impairment of renal function. No significant accumulation of Tenormin occurs in patients who have a creatinine clearance greater than 35 ml/min/1.73 m2 (normal range is 100-150 ml/min/1.73 m2). For patients with a creatinine clearance of 15-35 ml/min/1.73 m2 (equivalent to serum creatinine of 300-600 mmol/litre) the oral dose should be 50 mg daily and the intravenous dose should be 10 mg once every two days. For patients with a creatinine clearance of 2 (equivalent to serum creatinine of >600 mmol/litre) the oral dose should be 25 mg daily or 50 mg on alternate days and the intravenous dose should be 10 mg once every four days.

Patients on haemodialysis should be given 50 mg orally after each dialysis; this should be done under hospital supervision as marked falls in blood pressure can occur.

Overdosage Excessive bradycardia can be countered with atropine 1-2 mg IV. If necessary, this may be followed by a bolus dose of glucagon 10 mg IV. If required, this may be repeated or followed by an IV infusion of glucagon 1-10 mg/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 IV infusion or isoprenaline 10 to 25 micrograms given as an infusion at a rate not exceeding 5 micrograms/minute may be given. It is likely that these doses would be inadequate to reverse the cardiac effects of beta-blockade if a large overdose has been taken. The dose of dobutamine or isoprenaline should therefore be increased if necessary to achieve the required response according to the clinical condition of the patient.

There is a possibility of hypotension occurring following the use of beta-adrenoceptor agonists but this will be reduced by the use of the more selective agent dobutamine.

Storage/Handling Recommendations

Store at room temperature, protected from light and moisture

Review Date

2015-11-19 08:59:08