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)
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.
Indications
Cardiovascular
• Hypertension (not first-line) • Angina • Post-myocardial infarction • Certain arrhythmias
→ Hypertension Module → Anti-Anginal Module → Dysrhythmias Module
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.
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
Adverse Effects
• Bradycardia • Hypotension • Bronchospasm • Fatigue • Depression • Sexual dysfunction • Masked hypoglycemia
Avoid in:
• Asthma • Severe COPD
Contraindications
• Severe bradycardia • High-grade AV block (without pacemaker) • Cardiogenic shock • Acute decompensated heart failure
Use caution in:
• Diabetes (masks hypoglycemia) • Peripheral vascular disease
Propranolol vs Cardioselective Agents
Propranolol: • Blocks β1 and β2 • Higher bronchospasm risk • Greater CNS penetration
Cardioselective agents (e.g., Metoprolol): • Primarily block β1 • Safer in reactive airway disease
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:
→ Carvedilol → Metoprolol Succinate → Bisoprolol
Related:
→ Beta-Blockers Overview → Hypertension Module → Anti-Anginal Module → Dysrhythmias Module → Return to Cardiovascular Modules