Adenosine

Antiarrhythmics
Antiarrhythmics
High alert
An error with this medicine can cause serious harm: double checks and protocols are used.

A rapid intravenous push that blocks the AV node for a few seconds and stops most re-entrant supraventricular tachycardias.

Updated Nov 1, 2026

Quick facts

Group: Antiarrhythmics
Target: Adenosine A1 receptor (AV node)
Used for: PSVT that uses an accessory pathway
Key effects: Facial flushing · Chest pressure or pain
Monitor: Continuous ECG recording during the push
ATC: C01EB10

No doses: the clinician sets them by the current guideline.

Mechanism of action

Adenosine A1 receptor (AV node)Adenosine

The figure shows adenosine bound to the human adenosine A1 receptor coupled to its Gi protein; the structure also holds an allosteric modulator at a separate site.

Target in 3D: Adenosine A1 receptor (AV node). PDB structure 7LD3 (RCSB PDB, public domain). View the structure at RCSB PDB

Adenosine stimulates A1 receptors in the AV node and sinus node. Through Gi proteins it opens acetylcholine/adenosine-sensitive potassium channels and lowers cAMP and calcium entry, so the cells hyperpolarise and AV conduction is briefly blocked. Re-entry circuits that use the AV node (AVNRT, AVRT) are broken; atrial fibrillation, flutter and VT are not converted, though the ventricular rate may slow for a moment and unmask flutter waves.

Adenosine activates A1 receptors in the AV node
Potassium channels open and the nodal cells hyperpolarise
AV conduction stops for seconds, breaking the re-entry circuit
Red cells and endothelium take it up within seconds

Indications

Conversion of paroxysmal supraventricular tachycardia to sinus rhythm, after vagal manoeuvres Supraventricular tachycardia (AVNRT, AVRT) →
PSVT that uses an accessory pathway (Wolff-Parkinson-White), when the complex is regular and narrow Wolff-Parkinson-White syndrome →

Adverse effects

Common

Facial flushing
Chest pressure or pain and breathlessness
Headache and a sense of doom
Brief pauses or new rhythms at conversion

Contraindications

Second- or third-degree AV block without a working pacemaker
Sick sinus syndrome or symptomatic bradycardia without a pacemaker
Hypersensitivity to adenosine

Key interactions

Caffeine and theophylline (methylxanthines): Block adenosine receptors: larger doses may be needed or it may fail
Dipyridamole: Blocks adenosine uptake and strengthens its effect; smaller doses may be enough
Carbamazepine: Can deepen heart block
Digoxin, with or without verapamil: Rare reports of ventricular fibrillation

What is monitored

Continuous ECG recording during the push
Blood pressure and heart rate
Breathing and wheeze in patients with asthma

Administration and safety

Given as a rapid intravenous push directly into a peripheral vein, followed at once by a rapid saline flush, because it is cleared in seconds.
If given through a line, it is injected at the port closest to the patient.
A defibrillator and resuscitation equipment are at hand.
Not refrigerated, because crystals can form; the solution must be clear.

Pregnancy and breastfeeding

Adenosine is a natural body molecule with a very short half-life, so no fetal effects are expected, but human data are lacking and it is used in pregnancy only if clearly needed.

Nursing care

Warn the patient that flushing, chest pressure and a brief feeling of doom are expected and pass in seconds.
Run an ECG strip during the push to document the response and any pause.
Ask about asthma, caffeine intake, theophylline and dipyridamole beforehand.
After conversion, watch rhythm and blood pressure for recurrence.

Pharmacokinetics

Distribution: Cleared from blood within seconds by uptake into red cells and vascular endothelium
Metabolism: Phosphorylated to AMP or deaminated to inosine inside cells
Half-life: Less than ten seconds
Onset and duration: Seconds after a rapid push; adverse effects are brief

Test yourself

Think of the answer, then tap the question to see it.

Why is adenosine followed immediately by a rapid saline flush?

Its half-life is under ten seconds; the flush pushes it to the heart before red cells and endothelium take it up.

Which rhythms does adenosine convert and which does it not?

It converts re-entrant SVT that uses the AV node (AVNRT, AVRT); it does not convert atrial fibrillation, flutter or ventricular tachycardia.

How do theophylline and dipyridamole change the response to adenosine?

Theophylline (and caffeine) block its receptors and weaken it; dipyridamole blocks its uptake and strengthens it.

Which receptor in the AV node mediates adenosine's effect?

The A1 adenosine receptor, coupled to Gi, which opens potassium channels.

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Connections

← Back to the class: Antiarrhythmics

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - ADENOSINE injection (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); 7LD3: Cryo-EM structure of the human adenosine A1 receptor-Gi2-protein complex bound to its endogenous agonist and an allosteric ligand (RCSB Protein Data Bank, 2021).

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Representative model, for educational purposes only.