Pharm 101: Propranolol

Class

Beta-blocker
Class II antiarrhythmic

Pharmacodynamics
  • Competitive non-selective beta-blocker
  • Direct membrane effects (Na channel blockade) and prolongation of action potential duration
  • Cardiovascular effects:
    • Negative inotrope, negative chronotrope: reduces blood pressure primarily due to reduced cardiac output
    • Increased PR interval: increases AV nodal refractory period
    • Antagonises renin release from sympathetic nervous system: inhibits stimulation of renin production by catecholamines (mediated by beta-1 receptors)
  • Respiratory:
    • Bronchospasm
  • Opthalmological:
    • Decreased intra-ocular pressure
  • Metabolic:
    • Decreased glycogenolysis
Pharmacokinetics
  • 25% bioavailability
  • Highly lipid soluble
  • Half-life 3-5 hours
Clinical uses
  • Supraventricular arrhythmias
  • Thyrotoxicosis to control severe cardiovascular manifestations
  • Migraine prophylaxis (reduces frequency and intensity of migraines)
Adverse effects
  • Bradycardia
  • AV blockade
  • Hypotension
  • Bronchospasm
  • Reduced hypoglycaemia response
  • Toxicity:
    • In high doses has Na channel blocking effects similiar to TCAs
    • Seizures and cardiac conduction block
Further Reading
Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS CCPU (RCE, Biliary, DVT, E-FAST, AAA) Rob is an Emergency Medicine Advanced Trainee based in Melbourne, Australia. He has special interests in medical education, ECG interpretation, and the use of diagnostic and procedural ultrasound in the undifferentiated and unwell patient.

Follow him on twitter: @rob_buttner | ECG Library |

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