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 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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