What is the route of administration for adenosine when terminating AVNRT or AVRT?

• A. IV bolus
• B. Oral tablets
• C. Subcutaneous injection
• D. Intramuscular injection

Answer: (A)

Adenosine acts on receptors in the AV node to produce a brief period of nodal block, which interrupts AVNRT and AVRT circuits. Because its effects are incredibly short-lived, you need a rapid rise in blood concentration to have an immediate effect. An intravenous bolus achieves that rapid onset and short duration, making it the most reliable way to terminate these tachycardias. Other routes—oral, subcutaneous, or intramuscular—absorb too slowly or inconsistently to be effective for acute termination, so they aren’t suitable in this setting.