Atenolol

Atenolol is a cardioselective beta-1 blocker that has been used in the treatment of high blood pressure since the 1970s. One special feature is that atenolol is hardly broken down by the liver; instead, it is excreted almost unchanged by the kidneys.

Atenolol is used for high blood pressure, angina pectoris, and certain heart rhythm disorders. In recent years, it has been prescribed less often than bisoprolol or metoprolol, because newer studies showed a somewhat lower protective effect against stroke. However, it still has its place in therapy, particularly in patients with liver disease.

Atenolol selectively blocks beta-1 receptors:

Mechanism of action:

• Cardioselective beta-1 blockade
• Lowers heart rate and cardiac output
• Inhibits renin release
• No intrinsic sympathomimetic activity (ISA)

Pharmacokinetic characteristics:

• Hydrophilic beta blocker (water-soluble)
• Low passage across the blood-brain barrier
• Fewer central side effects (sleep disturbances, nightmares)
• No liver metabolism – renal elimination
• Half-life: 6-9 hours

Duration of action: The blood-pressure-lowering effect lasts about 24 hours, even though the half-life is shorter. Taking it once daily is sufficient for most patients.

Atenolol is suitable for:

• Adults with high blood pressure
• Angina pectoris
• Heart rhythm disorders (tachyarrhythmias)

Particularly suitable in:

• Liver disease (no hepatic metabolism)
• Patients with sleep disturbances on other beta blockers
• Cases where fewer CNS side effects are desired

Not suitable:

• Severe bronchial asthma
• Second- or third-degree AV block
• Severe bradycardia
• Decompensated heart failure
• Pheochromocytoma (untreated)

High blood pressure:

• Starting dose: 50 mg once daily
• Usual dose: 50-100 mg once daily
• Maximum dose: 100 mg daily

Angina pectoris:

• 50-100 mg once daily

In renal insufficiency:

• Creatinine clearance 10-30 ml/min: dose reduction to half the standard dose
• Creatinine clearance below 10 ml/min: dose reduction to one quarter of the standard dose

Available strengths:

• 25 mg, 50 mg, 100 mg tablets

How to take:

• Once daily, preferably in the morning
• Take before meals
• Swallow with enough water
• Always at the same time of day

Notes:

• Do not stop abruptly (taper off over 1-2 weeks)
• Regular blood pressure and pulse checks
• In renal insufficiency, observe the dose adjustment
• Inform the anesthesiologist before any surgery

If you miss a dose:

• Take it within a few hours
• Otherwise, take the next dose at the usual time
• Never take a double dose

Atenolol must not be taken in cases of:

• Hypersensitivity to atenolol
• Second- or third-degree AV block
• Sick sinus syndrome
• Severe bradycardia (below 50/min)
• Severe hypotension
• Cardiogenic shock
• Untreated pheochromocytoma
• Severe bronchial asthma
• Metabolic acidosis

Caution in:

• Renal insufficiency (dose adjustment)
• Diabetes mellitus
• Peripheral circulatory disorders
• Myasthenia gravis
• Psoriasis

Pregnancy: Only if strictly indicated. May cause growth retardation and neonatal bradycardia.

Common (1-10%):

• Fatigue
• Cold extremities
• Bradycardia
• Gastrointestinal complaints
• Dizziness

Uncommon (0.1-1%):

• Sleep disturbances (less frequent than with lipophilic beta blockers)
• Erectile dysfunction
• Muscle weakness
• Skin rash
• Dry eyes

Rare:

• Bronchospasm
• Depressed mood
• Elevated liver enzymes
• Worsening of psoriasis

Advantage: As a hydrophilic beta blocker, atenolol causes fewer nightmares and sleep disturbances than lipophilic beta blockers (metoprolol, propranolol), because it crosses the blood-brain barrier less readily.

Contraindicated with:

• Verapamil or diltiazem i.v.

Caution with:

• Calcium antagonists (verapamil, diltiazem) taken orally → increased bradycardia
• Antiarrhythmics → additive cardiodepressant effect
• Clonidine → excessive rise in blood pressure if clonidine is stopped abruptly while taking atenolol (only stop clonidine once atenolol has been discontinued a few days beforehand)
• Digitalis preparations → increased bradycardia
• NSAIDs → reduced lowering of blood pressure
• Anesthetics → increased effect on the heart

Note: Because atenolol is not broken down by the liver, there are fewer pharmacokinetic interactions via CYP enzymes than with metoprolol.