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cardio:beta_blockers:start [2026/02/12 23:25] – created andrew2393cnscardio:beta_blockers:start [2026/02/12 23:47] (current) – [Mechanism of Action] andrew2393cns
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 ====== Beta-Blockers ====== ====== Beta-Blockers ======
  
-Beta-blockers inhibit beta-adrenergic receptors and reduce sympathetic stimulation of the heart and kidneys.+Beta-blockers antagonize beta-adrenergic receptors and reduce sympathetic stimulation of the cardiovascular system.
  
-They are used in:+Primary Physiologic Effects:
  
-• Hypertension   +• ↓ Heart rate   
-• Heart failure (HFrEF)   +• ↓ Contractility   
-• Coronary artery disease   +• ↓ Renin release   
-• Arrhythmias  +• ↓ Cardiac output   
 +• ↓ Blood pressure   
 + 
 +Used in: 
 + 
 +• [[cardio:hypertension:start|Hypertension]]   
 +• [[cardio:heart_failure:start|Heart Failure (HFrEF)]]   
 +• [[cardio:arrhythmias:start|Arrhythmias]]   
 +• [[cardio:angina:start|Angina]]  
 • Post-myocardial infarction   • Post-myocardial infarction  
  
-Their primary effects are reduction of heart rate, contractility, and renin release.+★ = Most commonly used / high-yield agents
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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 ===== Mechanism of Action ===== ===== Mechanism of Action =====
  
-Beta receptors:+β1 receptors: 
 +• Heart (↑ HR, ↑ contractility) 
 +• Kidney (↑ renin)
  
-• β1 – Heart & kidney (↑ HR, ↑ contractility, ↑ renin)   +β2 receptors: 
-• β2 – Bronchi & vascular smooth muscle (bronchodilation, vasodilation)+• Bronchi (bronchodilation) 
 +• Vascular smooth muscle
  
 Beta-blockers: Beta-blockers:
  
-• Block β1 (cardiac effects)   +• Block β1 (cardiac effects) 
-• Some also block β2   +• Some also block β2 
-• Some also block α1  +• Some provide additional vasodilation (α1 or NO-mediated)
  
-Net Effects:+Reference: [[autonomics:start|Autonomic Receptors]]
  
-• ↓ Heart rate   +-------------------------------------------------------------------- 
-• ↓ Contractility   + 
-• ↓ Cardiac output   +===== Generations of Beta-Blockers ===== 
-• ↓ Renin release   + 
-• ↓ Blood pressure  +==== 1st Generation – Nonselective (β1 + β2 Blockade) ==== 
 + 
 +Block both β1 and β2 receptors. 
 + 
 +• ★ [[cardio:beta_blockers:propranolol|Propranolol]] 
 +• [[cardio:beta_blockers:nadolol|Nadolol]] 
 +• [[cardio:beta_blockers:timolol|Timolol]] 
 +• [[cardio:beta_blockers:sotalol|Sotalol]] 
 +• [[cardio:beta_blockers:penbutolol|Penbutolol]] 
 +• [[cardio:beta_blockers:carteolol|Carteolol]] 
 + 
 +Clinical Notes: 
 + 
 +• Avoid in asthma / severe COPD   
 +• Sotalol also has Class III antiarrhythmic activity  
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
  
-===== Classification =====+==== 2nd Generation – Cardioselective (β1 Selective) ====
  
-==== Cardioselective (β1-Selective) ====+Primarily block β1 receptors.
  
-• [[cardio:beta_blockers:metoprolol|Metoprolol]] +• ★ [[cardio:beta_blockers:metoprolol|Metoprolol]] 
-• [[cardio:beta_blockers:atenolol|Atenolol]] +• ★ [[cardio:beta_blockers:bisoprolol|Bisoprolol]] 
-• [[cardio:beta_blockers:bisoprolol|Bisoprolol]]+• ★ [[cardio:beta_blockers:atenolol|Atenolol]] 
 +• ★ [[cardio:beta_blockers:esmolol|Esmolol]] (IV, ultra short-acting)
 • [[cardio:beta_blockers:nebivolol|Nebivolol]] • [[cardio:beta_blockers:nebivolol|Nebivolol]]
 +• [[cardio:beta_blockers:acebutolol|Acebutolol]]
 +• [[cardio:beta_blockers:betaxolol|Betaxolol]]
 +• [[cardio:beta_blockers:celiprolol|Celiprolol]]
  
-Preferable in: +Clinical Notes:
-• Reactive airway disease   +
-• Diabetes  +
  
-----+• Preferred in reactive airway disease   
 +• Selectivity is dose-dependent   
 +• Esmolol used in ICU / acute arrhythmias  
  
-==== Nonselective (β1 + β2) ====+--------------------------------------------------------------------
  
-• [[cardio:beta_blockers:propranolol|Propranolol]] +==== 3rd Generation – Vasodilating Beta-Blockers ====
-• [[cardio:beta_blockers:nadolol|Nadolol]] +
-• [[cardio:beta_blockers:timolol|Timolol]]+
  
-Avoid in: +Provide additional vasodilation via α1 blockade or nitric oxide release.
-• Asthma   +
-• Severe COPD  +
  
-----+Alpha/Beta Blockade:
  
-==== Combined α/β Blockers ====+• ★ [[cardio:beta_blockers:carvedilol|Carvedilol]] 
 +• ★ [[cardio:beta_blockers:labetalol|Labetalol]]
  
-• [[cardio:beta_blockers:labetalol|Labetalol]] +Nitric Oxide–Mediated:
-• [[cardio:beta_blockers:carvedilol|Carvedilol]]+
  
-Effect: +• ★ [[cardio:beta_blockers:nebivolol|Nebivolol]]
-• ↓ HR (β1) +
-• ↓ SVR (α1 blockade)+
  
-Useful in: +Less Common:
-• Hypertensive emergency   +
-• Heart failure (carvedilol)+
  
-----+• [[cardio:beta_blockers:bucindolol|Bucindolol]]
  
-==== Agents with Intrinsic Sympathomimetic Activity (ISA) ====+Clinical Notes:
  
-• [[cardio:beta_blockers:pindolol|Pindolol]] +• Lower SVR in addition to HR reduction   
-• [[cardio:beta_blockers:acebutolol|Acebutolol]] +• Carvedilol reduces mortality in HFrEF   
- +• Labetalol commonly used in hypertensive emergencies  
-Partial agonist activity. +
-Less commonly used.+
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
  
-===== Indications =====+===== Beta-Blocker Comparison Table =====
  
-==== Hypertension ====+^ Drug ^ Generation ^ Beta-1 Selective ^ Alpha-1 / Vasodilation ^ Lipophilic vs Hydrophilic ^ HFrEF Mortality Benefit ^ Common Uses ^ 
 +|[[cardio:beta_blockers:propranolol|Propranolol]] | 1st | No | No | Lipophilic | No | Migraine, tremor, portal HTN | 
 +| [[cardio:beta_blockers:sotalol|Sotalol]] | 1st | No | No | Hydrophilic | No | AF, ventricular arrhythmias | 
 +|[[cardio:beta_blockers:metoprolol|Metoprolol]] | 2nd | Yes | No | Lipophilic | Only Succinate | HTN, CAD, AF | 
 +|[[cardio:beta_blockers:bisoprolol|Bisoprolol]] | 2nd | Yes | No | Moderate | Yes | HFrEF, HTN | 
 +|[[cardio:beta_blockers:atenolol|Atenolol]] | 2nd | Yes | No | Hydrophilic | No | HTN (historical) | 
 +|[[cardio:beta_blockers:esmolol|Esmolol]] | 2nd | Yes | No | Hydrophilic | No | ICU rate control | 
 +|[[cardio:beta_blockers:carvedilol|Carvedilol]] | 3rd | No | Yes (alpha-1) | Lipophilic | Yes | HFrEF, HTN | 
 +|[[cardio:beta_blockers:labetalol|Labetalol]] | 3rd | No | Yes (alpha-1) | Moderate | No | HTN emergency, pregnancy | 
 +|[[cardio:beta_blockers:nebivolol|Nebivolol]] | 3rd | Yes | Nitric Oxide-Mediated | Lipophilic | No | HTN | 
 +===== Intrinsic Sympathomimetic Activity (ISA) =====
  
-• Not first-line for uncomplicated HTN   +Partial agonist activity:
-• Useful in CAD, arrhythmia, HFrEF  +
  
-→ [[cardio:hypertension:start|Hypertension Module]]+• [[cardio:beta_blockers:pindolol|Pindolol]] 
 +• [[cardio:beta_blockers:acebutolol|Acebutolol]] 
 +• [[cardio:beta_blockers:penbutolol|Penbutolol]]
  
-----+Less commonly used in modern practice.
  
-==== Heart Failure (HFrEF) ====+--------------------------------------------------------------------
  
-Mortality-reducing agents:+===== Evidence-Based Heart Failure Agents (Mortality Benefit) =====
  
-• [[cardio:beta_blockers:carvedilol|Carvedilol]] +• ★ [[cardio:beta_blockers:carvedilol|Carvedilol]] 
-• [[cardio:beta_blockers:metoprolol_succinate|Metoprolol Succinate]] +• ★ [[cardio:beta_blockers:metoprolol|Metoprolol Succinate]] 
-• [[cardio:beta_blockers:bisoprolol|Bisoprolol]]+• ★ [[cardio:beta_blockers:bisoprolol|Bisoprolol]]
  
 → [[cardio:heart_failure:start|Heart Failure Module]] → [[cardio:heart_failure:start|Heart Failure Module]]
  
-----+Not all beta-blockers reduce mortality in HFrEF.
  
-==== Coronary Artery Disease / Post-MI ====+--------------------------------------------------------------------
  
-• Reduce myocardial oxygen demand   +===== Indications by Clinical Context =====
-• Reduce mortality post-MI  +
  
-----+Hypertension: 
 +• Not first-line for uncomplicated HTN   
 +• Preferred when CAD, arrhythmia, or HFrEF present  
  
-==== Arrhythmias ====+→ [[cardio:hypertension:start|Hypertension Module]]
  
 +Arrhythmias:
 • Rate control in atrial fibrillation   • Rate control in atrial fibrillation  
-• Suppress SVT  +• SVT suppression  
  
 → [[cardio:arrhythmias:start|Dysrhythmias Module]] → [[cardio:arrhythmias:start|Dysrhythmias Module]]
 +
 +Angina:
 +• Reduce myocardial oxygen demand  
 +
 +→ [[cardio:angina:start|Anti-Anginal Module]]
 +
 +Hypertensive Emergency:
 +• ★ [[cardio:beta_blockers:labetalol|Labetalol]]
 +• ★ [[cardio:beta_blockers:esmolol|Esmolol]]
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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 • Bradycardia   • Bradycardia  
 +• AV block  
 • Hypotension   • Hypotension  
 • Fatigue   • Fatigue  
 • Depression   • Depression  
 • Erectile dysfunction   • Erectile dysfunction  
-• Mask hypoglycemia  +• Masked hypoglycemia  
 • Bronchospasm (nonselective agents) • Bronchospasm (nonselective agents)
  
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 • High-grade AV block (without pacemaker)   • High-grade AV block (without pacemaker)  
 • Cardiogenic shock   • Cardiogenic shock  
-• Decompensated heart failure  +• Acute decompensated heart failure  
  
 Use caution in: Use caution in:
 +
 • Asthma   • Asthma  
 • Severe peripheral vascular disease   • Severe peripheral vascular disease  
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 ===== Clinical Pearls ===== ===== Clinical Pearls =====
  
-✔ Reduce mortality in HFrEF (select agents only)   +✔ Only certain agents reduce mortality in HFrEF  
-✔ Not first-line for uncomplicated hypertension   +
-✔ Cardioselective agents preferred in lung disease   +
-✔ Avoid abrupt discontinuation (rebound tachycardia)   +
-✔ Combined α/β agents reduce SVR and HR  +
  
---------------------------------------------------------------------+✔ 1st gen = nonselective  
  
-===== Relationship to Other Classes =====+✔ 2nd gen = β1 selective  
  
-Often combined with:+✔ 3rd gen = vasodilating  
  
-• [[cardio:raas:acei|ACE Inhibitors]] +✔ Avoid abrupt discontinuation (rebound tachycardia)   
-• [[cardio:raas:arb|ARBs]] + 
-• [[cardio:diuretics:start|Diuretics]] +✔ Not first-line for uncomplicated hypertension  
-• [[cardio:ccb:non_dhp|Non-DHP CCBs]] (use caution)+
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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 Related: Related:
  
-→ [[cardio:hypertension:start|Hypertension Module]] +→ [[cardio:hypertension:start|Hypertension Module]]   
-→ [[cardio:heart_failure:start|Heart Failure Module]] +→ [[cardio:heart_failure:start|Heart Failure Module]]   
-→ [[cardio:arrhythmias:start|Dysrhythmias Module]]+→ [[cardio:arrhythmias:start|Dysrhythmias Module]]  
 → [[cardio:intro:start|Return to Cardiovascular Modules]] → [[cardio:intro:start|Return to Cardiovascular Modules]]
cardio/beta_blockers/start.1770938728.txt.gz · Last modified: by andrew2393cns