Pharm 101: Adenosine

Class

Antiarrhythmic


Pharmacodynamics
  • Adenosine is a naturally occurring nucleoside
  • As a bolus dose blocks AV nodal conduction and increases AV nodal refractory period due to:
    • Activation of inward rectifier K current
    • Inhibition of Ca current
    • Results in hyperpolarisation and suppression of calcium-dependent action potentials
  • This interrupts re-entry pathway through AV node

Pharmacokinetics
  • Very rapid metabolism by adenosine deaminase in red cells and endothelial wall
  • Half-life < 10 seconds
  • Duration of action ~ 30 seconds

Clinical uses
  • Conversion of paroxysmal SVT to sinus rhythm:
    • Given via rapid IV bolus, proximal IV site
    • If initial dose ineffective, subsequent doses should be increased (no accumulation occurs)
  • An uncommon variant of VT is adenosine-sensitive
  • Will not be effective for SVT caused by adenosine-blockers such as theophylline

Adverse effects
  • Short-lived
  • Flushing 20%
  • SOB or chest burning (likely bronchospasm-related) 10%
  • Short-lived induction of high grade AV block
  • AF
  • Sense of impending doom

Precautions/contraindications
  • Drug interactions:
    • Adenosine receptor blockers: theophylline, caffeine (reduce effectiveness)
    • Adenosine uptake inhibitors: dipyridamole (increases effectiveness)
    • Interaction with other AV nodal blocking drugs
  • AV block
  • Acute asthma

Further Reading

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU Emergency Medicine Trainee with interests in medical education, ECG interpretation, and the use of point-of-care ultrasound in the undifferentiated patient. Co-author of the LITFL ECG Library | Twitter

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.