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 (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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