Adenosine is used for acute conversion of paroxysmal SVT. Its ultra-short duration of action (~10 seconds) is due to:

• A Rapid hepatic first-pass metabolism by CYP2D6
• B Renal filtration and excretion unchanged in urine
• C Rapid cellular uptake by the equilibrative nucleoside transporter and phosphorylation within red blood cells and endothelium ✓
• D Rapid hydrolysis by plasma esterases to inosine

Explanation

Adenosine has an extremely short plasma half-life (~10 seconds) because it is rapidly taken up into red blood cells and endothelial cells by the equilibrative nucleoside transporter (ENT1), then phosphorylated to AMP (and further) by adenosine kinase, or deaminated to inosine by adenosine deaminase. This cellular sequestration and metabolism, not hepatic or renal clearance, accounts for its instantaneous termination of SVT. Dipyridamole (which blocks ENT1) potentiates and prolongs adenosine's effect.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.