====== Propranolol ======

Propranolol is a 1st-generation, nonselective beta-blocker that blocks both β1 and β2 receptors.

It is one of the oldest and most widely studied beta-blockers.

Classification:
• 1st Generation (Nonselective)
• No intrinsic sympathomimetic activity (ISA)

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

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

Blocks:

• β1 receptors → ↓ Heart rate, ↓ contractility, ↓ renin
• β2 receptors → ↓ Bronchodilation, ↓ peripheral vasodilation

Net Effects:

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

Because it blocks β2 receptors, bronchospasm is possible.

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===== Indications =====

==== Cardiovascular ====

• Hypertension (not first-line)
• Angina
• Post-myocardial infarction
• Certain arrhythmias

→ [[cardio:hypertension:start|Hypertension Module]]
→ [[cardio:angina:start|Anti-Anginal Module]]
→ [[cardio:arrhythmias:start|Dysrhythmias Module]]

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==== Non-Cardiac (High-Yield Uses) ====

• Essential tremor
• Migraine prophylaxis
• Hyperthyroidism (symptom control)
• Performance anxiety
• Portal hypertension (variceal bleed prevention)

These extra-cardiac uses make propranolol uniquely versatile.

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===== Pharmacokinetics =====

• Lipophilic (crosses blood-brain barrier)
• Extensive first-pass metabolism
• Short to moderate half-life
• Available in immediate and extended-release forms

CNS penetration explains:

• Fatigue
• Depression
• Vivid dreams

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

• Bradycardia
• Hypotension
• Bronchospasm
• Fatigue
• Depression
• Sexual dysfunction
• Masked hypoglycemia

Avoid in:

• Asthma
• Severe COPD

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===== Contraindications =====

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

Use caution in:

• Diabetes (masks hypoglycemia)
• Peripheral vascular disease

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===== Propranolol vs Cardioselective Agents =====

Propranolol:
• Blocks β1 and β2
• Higher bronchospasm risk
• Greater CNS penetration

Cardioselective agents (e.g., [[cardio:beta_blockers:metoprolol|Metoprolol]]):
• Primarily block β1
• Safer in reactive airway disease

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

✔ Prototype nonselective beta-blocker  
✔ Excellent for migraine and tremor  
✔ Avoid in asthma  
✔ Crosses blood-brain barrier  
✔ Not preferred in HFrEF  

For heart failure mortality benefit, see:

→ [[cardio:beta_blockers:carvedilol|Carvedilol]]
→ [[cardio:beta_blockers:metoprolol_succinate|Metoprolol Succinate]]
→ [[cardio:beta_blockers:bisoprolol|Bisoprolol]]

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Related:

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