====== Atenolol ======

Atenolol is a 2nd-generation, β1-selective beta-blocker.

It reduces heart rate, contractility, and renin release with minimal β2 blockade at usual doses.

Classification:
• 2nd Generation (Cardioselective)
• No intrinsic sympathomimetic activity (ISA)

→ [[cardio:beta_blockers:start|Beta-Blockers Overview]]

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===== Mechanism of Action =====

Selective β1 blockade:

• ↓ Heart rate  
• ↓ Contractility  
• ↓ AV nodal conduction  
• ↓ Renin release  

Net Effects:

• ↓ Cardiac output  
• ↓ Blood pressure  
• ↓ Myocardial oxygen demand  

Selectivity is dose-dependent.

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===== Indications =====

==== Hypertension ====

• Historically widely used  
• Not first-line for uncomplicated HTN  
• Inferior outcome data compared to other agents  

→ [[cardio:hypertension:start|Hypertension Module]]

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==== Coronary Artery Disease / Angina ====

• Reduces myocardial oxygen demand  
• Used for chronic stable angina  

→ [[cardio:angina:start|Anti-Anginal Module]]

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==== Arrhythmias ====

• Rate control (less commonly used than metoprolol)  

→ [[cardio:arrhythmias:start|Dysrhythmias Module]]

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===== Important Distinction in Heart Failure =====

Atenolol does NOT have proven mortality benefit in HFrEF.

Evidence-based HFrEF beta-blockers are:

• [[cardio:beta_blockers:carvedilol|Carvedilol]]
• [[cardio:beta_blockers:metoprolol|Metoprolol Succinate]]
• [[cardio:beta_blockers:bisoprolol|Bisoprolol]]

→ [[cardio:heart_failure:start|Heart Failure Module]]

This is a common exam distinction.

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===== Pharmacokinetics =====

• Hydrophilic (less CNS penetration than propranolol)
• Primarily renally excreted
• Once-daily dosing common

Dose adjustment required in renal impairment.

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===== Adverse Effects =====

• Bradycardia  
• Hypotension  
• Fatigue  
• Cold extremities  
• Masked hypoglycemia  

Lower bronchospasm risk than nonselective agents.

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===== Contraindications =====

• Severe bradycardia  
• High-grade AV block (without pacemaker)  
• Cardiogenic shock  
• Acute decompensated heart failure  

Use caution in:
• Asthma (safer than nonselective agents)
• Diabetes
• Renal impairment

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===== Atenolol vs Metoprolol =====

[[cardio:beta_blockers:metoprolol|Metoprolol]]:
• More commonly used today  
• Stronger outcome data  
• Succinate form reduces mortality in HFrEF  

Atenolol:
• Older agent  
• Less outcome data in hypertension  
• No mortality benefit in HFrEF  

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===== Clinical Pearls =====

✔ β1 selective  
✔ Renally cleared  
✔ No proven HFrEF mortality benefit  
✔ Not first-line for uncomplicated hypertension  
✔ Historically common but declining use  

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Related:

→ [[cardio:beta_blockers:start|Beta-Blockers Overview]]
→ [[cardio:hypertension:start|Hypertension Module]]
→ [[cardio:angina:start|Anti-Anginal Module]]
→ [[cardio:heart_failure:start|Heart Failure Module]]
→ [[cardio:intro:start|Return to Cardiovascular Modules]]