Beta-blockers antagonize beta-adrenergic receptors and reduce sympathetic stimulation of the cardiovascular system.

Primary Physiologic Effects:

• ↓ Heart rate • ↓ Contractility • ↓ Renin release • ↓ Cardiac output • ↓ Blood pressure

Used in:

• Hypertension • Heart Failure (HFrEF) • Arrhythmias • Angina • Post-myocardial infarction

★ = Most commonly used / high-yield agents

β1 receptors: • Heart (↑ HR, ↑ contractility) • Kidney (↑ renin)

β2 receptors: • Bronchi (bronchodilation) • Vascular smooth muscle

Beta-blockers:

• Block β1 (cardiac effects) • Some also block β2 • Some provide additional vasodilation (α1 or NO-mediated)

Reference: autonomics

Block both β1 and β2 receptors.

• ★ Propranolol • Nadolol • Timolol • Sotalol • Penbutolol • Carteolol

Clinical Notes:

• Avoid in asthma / severe COPD • Sotalol also has Class III antiarrhythmic activity

Primarily block β1 receptors.

• ★ Metoprolol • ★ Bisoprolol • ★ Atenolol • ★ Esmolol (IV, ultra short-acting) • Nebivolol • Acebutolol • Betaxolol • Celiprolol

Clinical Notes:

• Preferred in reactive airway disease • Selectivity is dose-dependent • Esmolol used in ICU / acute arrhythmias

Provide additional vasodilation via α1 blockade or nitric oxide release.

Alpha/Beta Blockade:

• ★ Carvedilol • ★ Labetalol

Nitric Oxide–Mediated:

• ★ Nebivolol

Less Common:

• Bucindolol

Clinical Notes:

• Lower SVR in addition to HR reduction • Carvedilol reduces mortality in HFrEF • Labetalol commonly used in hypertensive emergencies

Partial agonist activity:

• Pindolol • Acebutolol • Penbutolol

Less commonly used in modern practice.

• ★ Carvedilol • ★ Metoprolol Succinate • ★ Bisoprolol

→ Heart Failure Module

Not all beta-blockers reduce mortality in HFrEF.

Hypertension: • Not first-line for uncomplicated HTN • Preferred when CAD, arrhythmia, or HFrEF present

→ Hypertension Module

Arrhythmias: • Rate control in atrial fibrillation • SVT suppression

→ Dysrhythmias Module

Angina: • Reduce myocardial oxygen demand

→ Anti-Anginal Module

Hypertensive Emergency: • ★ Labetalol • ★ Esmolol

• Bradycardia • AV block • Hypotension • Fatigue • Depression • Erectile dysfunction • Masked hypoglycemia • Bronchospasm (nonselective agents)

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

Use caution in:

• Asthma • Severe peripheral vascular disease

✔ Only certain agents reduce mortality in HFrEF ✔ 1st gen = nonselective ✔ 2nd gen = β1 selective ✔ 3rd gen = vasodilating ✔ Avoid abrupt discontinuation (rebound tachycardia) ✔ Not first-line for uncomplicated hypertension

Related:

→ Hypertension Module → Heart Failure Module → Dysrhythmias Module → Return to Cardiovascular Modules