Tenbeta 50 (Atenolol)
- Management of hypertension
- Management of angina pectoris
- Management of cardiac arrhythmias
- Management of myocardial infarction. Early intervention in the acute phase
Since atenolol is excreted via the kidneys the dosage should be adjusted in cases of severe impairment of renal function. No significant accumulation of atenolol occurs in patients who have a creatinine clearance greater than 35mil per min per 1.73m2.
For patients with a creatinine clearance of 15 to 35ml per minutes per1.73m2 (equivalent to serum creatinine of 300-600 micromol per litre) the oral dose should be 50 mg daily and the intravenous dose should be 10mg once every two 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.
Atenolol as with other beta-blocker, should not be used in patients with any of the following:
- Cardiogenic shock
- Uncontrolled heart failure
- Second or third degree heart block
- Untreated phaeochromocytom
- Metabolic acidosis
- Known hypersensitivity to the active substances or any of the excipients.
- Severe peripheral arterial circulatory disturbances
Atenolol as with other beta blockers: Should not be withdrawn abruptly. The dosage should be withdrawn gradually over a period of 7-14 days, to facilitate a reduction in beta blocker dosage.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-blocker should be made for each patient. If treatment is continued, an anesthetic with little negative inotropic activity should be selected to minimize the risk of myocardial depression.
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. Atenolol 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 beta 1-selective beta-blocker; consequently, its use may be considered although utmost caution must be exercised.
It may mask the symptoms of hypoglycemia, in particular, tachycardia Atenolol may mask the signs of thyro toxicosis
Pregnancy and lactation
Atenolol crosses the placenta barrier and appears in the cord blood. The use of atenolol in the first trimester and the possibility of foetal injury cannot be excluded. Atenolol has been used under close supervision for the treatment of hypertension in the third trimester. Administration of Atenolol to pregnant women in the management of mild to moderate hypertension has been associated with intra uterine growth retardation.
There is significant accumulation of atenolol in breast milk. Neonates born to mothers who are receiving atenolol at parturition or breast-feeding may be at risk of hypoglycemia and bradycardia. Caution should be exercised when Atenolol is administered during pregnancy or to a woman who is breast-feeding.
Effects on ability to drive and use machines
Use is unlikely to result in any impairment of the ability to patients to drive or operate machinery. However, it should be taken into account that occasionally dizziness or fatigue may occur.
Cardiovascular: bradycardia, heart failure deterioration, postural hypotension which may be associated with syncope
CNS: confusion, dizziness, headache, mood changes, nightmaires, sleep disturbances
Gastrointestinal: dry mouth, gastrointestinal disturbances
Haematological: Purpura, thrombocytopenia
Integumentary: alopecia, dry eyes, psoriasis from skin reactions, excarbation of psoriasis
Atenolol is a beta-blocker, which is beta1-selective, selectivity decreases with increasing dose. Atenolol is without intrinsic sympathomimetic and membrane stabilizing activities and as with other beta-blockers, has negative inotropic effects.
As with other beta-blockers, 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 which makes it effective in eliminating or reducing the symptoms of patients with Angina.
Psology and method of administration
As directed by physician or pharmacist:
Hypertension: one tablet daily. Most patients respond to 100mg daily given orally as single dose. Some patients will respond to 50 mg given as single daily dose. The effects will be established after one to two weeks.
Angina: Most patients with angina pectoris will respond to 100 mg given orally once daily or 50 mg given twice daily.
Cardiac Arrhythmias: A suitable initial dose is 2.5 mg (5ml) injected intravenously over a 2.5 minutes period. (1mg/min). This may be repeated at 5 minute intervals until a response is observed up to a maximum dose of 10 mg
Myocardial Infarction: For patients suitable for treatment with intravenous beta-blockade and representing within 12 hours of the onset of chest pain, Atenolol 5-10 mg should be given by slow intravenous injection (1mg/min) followed by Atenolol 50 mg orally about 15 minutes later, provided no untoward effects have occurred from the intravenous dose.