Pharmacokinetic Properties
In terms of its physicochemical properties, atenolol is a hydrophilic compound. Its low lipophilicity directly determines several key pharmacokinetic parameters. First, absorption from the gastrointestinal tract is incomplete, resulting in an oral bioavailability of only about 50%.
Second, hydrophilicity causes the drug to cross the blood-brain barrier (BBB) very poorly. Consequently, unlike lipophilic propranolol, atenolol exerts minimal, negligible effects on the central nervous system (CNS). This makes it a preferred choice for patients prone to neurological adverse reactions.
Cardioselectivity and Safety
One of the most important characteristics of atenolol is its relative, moderate cardioselectivity. The selectivity index of this drug is 14–35, which is considered low compared to more modern analogs.
Clinical significance: Because of this moderate selectivity, atenolol retains the potential to cause adverse effects typically associated with non-selective beta-blockers. While these undesirable effects occur less frequently than with truly non-selective agents, physicians must account for the risk of their development when prescribing therapy.
Indications, Dosing, and Duration of Action
In clinical practice, the drug is prescribed for the following conditions:
- Hypertension (for blood pressure control);
- Angina pectoris (as part of anti-anginal therapy);
- Arrhythmias (for heart rhythm stabilization).
The drug is administered either intravenously or orally. For oral administration, the standard dosing regimen involves taking the medication twice daily.
In terms of duration of action, atenolol occupies an intermediate position among beta-blockers: it acts longer than metoprolol, but its effect is shorter than that of nadolol. The half-life ($t_{1/2}$) is 6–7 hours. Notably, after a single dose, the clinical therapeutic effect can persist for up to 24 hours.