None known.
Atenolol Calox is a drug on which extensive clinical experience has been obtained. Relevant information for the prescriber is provided elsewhere in the Prescribing Information.
Pharmacotherapeutic group: Beta-blocking agents, plain, selective.
ATC code: CO7A B03.
Mechanism of action
Atenolol Calox is a beta-blocker, which is beta1-selective, (i.e. acts preferentially on beta1-adrenergic receptors in the heart). Selectivity decreases with increasing dose.
Atenolol Calox is without intrinsic sympathomimetic and membrane-stabilising activities and as with other beta-blockers, has negative inotropic effects (and is therefore contraindicated in uncontrolled heart failure).
As with other beta-blockers, the mode of action of Atenolol Calox in the treatment of hypertension is unclear. It is probably the action of Atenolol Calox in reducing cardiac rate and contractility, which 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 Calox, in comparison with the racemic mixture, will give rise to different therapeutic effects.
Clinical efficacy and safety
Atenolol Calox is effective and well tolerated in most ethnic populations although the response may be less in black patients.
Atenolol Calox is effective for at least 24 hours after a single oral dose. The drug facilitates compliance by its acceptability to patients and simplicity of dosing. The narrow dose range and early patient response ensure that the effect of the drug in individual patients is quickly demonstrated. Atenolol Calox is compatible with diuretics, other hypotensive agents and antianginals. Since it acts preferentially on beta-receptors in the heart, Atenolol Calox may, with care, be used successfully in the treatment of patients with respiratory disease, who cannot tolerate non-selective beta-blockers.
Early intervention with Atenolol Calox 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 Calox is an additional treatment to standard coronary care.
Absorption
Absorption of Atenolol Calox following oral dosing is consistent but incomplete (approximately 40-50%) with peak plasma concentrations occurring 2-4 hours after dosing. The bioavailability is decreased by 20% when taken with food. There is a linear relationship between dosage and plasma concentration. The inter-subject variability in AUC and Cmax is about 30-40%. There is no significant hepatic metabolism of Atenolol Calox and more than 90% of that absorbed reaches the systemic circulation unaltered.
Distribution
Atenolol Calox penetrates tissues poorly due to its low lipid solubility and its concentration in brain tissue is low. The volume of distribution is 50 to 75 L. The protein binding is low (approximately 3%). Most of an absorbed dose (85-100%) is excreted unchanged via the urine.
Elimination
The clearance is about 6 l/h and the half-life is about 6 to 9 hours. In elderly patients, clearance is decreased and elimination half-life increased. The clearance is correlated to renal function and the elimination is prolonged in patients with renal impairment. Impaired liver function does not influence the pharmacokinetics of Atenolol Calox.
No special requirements
