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Antiarrhythmic Pregnancy: No or limited data from use in pregnant women and insufficient animal reproductive toxicity data; not recommended during pregnancy unless the physician considers the benefits to outweigh the potential risks. Should not be used during breast-feeding.

Adenosine

Brand names: Adenocor

Adenosine is an endogenous purine nucleoside given as a rapid intravenous bolus, used in the emergency setting to terminate paroxysmal supraventricular tachycardia and to unmask atrial activity in broad-complex or undifferentiated regular tachycardias.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Initial dose 3 mg as a rapid intravenous bolus (over 2 seconds). Second dose: if the first dose does not eliminate the supraventricular tachycardia within 1 to 2 minutes, give 6 mg as a rapid IV bolus. Third dose: if the second dose does not eliminate the SVT within 1 to 2 minutes, give 12 mg as a rapid IV bolus
Route: Rapid intravenous bolus injection, directly into a vein or into an IV line — inject as proximally as possible and follow with a rapid saline flush; use a large-bore cannula if given through a peripheral vein
Frequency: Ascending schedule, each step given 1 to 2 minutes after the preceding dose if the SVT has not terminated
Max: 12 mg — additional or higher doses are not recommended
eMC (Adenosine 3 mg/ml solution for injection). Intended for hospital use only, with monitoring and cardiorespiratory resuscitation equipment available for immediate use; should only be used where facilities exist for cardiac monitoring, and continuous ECG monitoring is necessary during administration as life-threatening arrhythmia might occur. Patients who develop high-level AV block at a particular dose should not be given further dosage increments. Elderly: see dosage recommendations for adults. Diagnostic use: the same ascending schedule is employed until sufficient diagnostic information has been obtained; rapid intravenous injection only. Each vial is for single use; inspect visually and use only clear, colourless solution. Note: the US label in the fetched bundle was an unrelated topical cosmetic sunscreen product and was NOT used.

Paediatric dose

Dose: 0.1 mg/kg
Route: Rapid intravenous bolus injection
Frequency: First bolus 0.1 mg/kg body weight, then increments of 0.1 mg/kg body weight as needed to achieve termination of the supraventricular tachycardia
Max: Maximum 6 mg for the first bolus; maximum 12 mg for the subsequent increments
SPC dosing for paroxysmal supraventricular tachycardia in the paediatric population. Cardio-respiratory resuscitation equipment must be available for immediate use during administration, with continuous monitoring and ECG recording. Clinician to verify against a children's formulary before use.

Dose adjustments

Renal

Since neither the kidney nor the liver is involved in the degradation of exogenous adenosine, efficacy should be unaffected by hepatic or renal insufficiency (no dose adjustment stated).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

SPC dosing for paroxysmal supraventricular tachycardia in the paediatric population. Cardio-respiratory resuscitation equipment must be available for immediate use during administration, with continuous monitoring and ECG recording. Clinician to verify against a children's formulary before use.

Verify in a children's formulary

Contraindications

  • Known hypersensitivity to adenosine or to any of the excipients
  • Sick sinus syndrome, or second or third degree atrioventricular block (except in patients with a functioning artificial pacemaker)
  • Chronic obstructive lung disease with evidence of bronchospasm (e.g. asthma bronchiale)
  • Long QT syndrome
  • Severe hypotension
  • Decompensated states of heart failure

Side effects

  • Chest pressure/pain, feeling of thoracic constriction (very common)
  • Flushing (very common)
  • Dyspnoea, or the urge to take a deep breath (very common)
  • Bradycardia, sinus pause, skipped beats, atrial extrasystoles, atrioventricular block, ventricular extrasystoles and non-sustained ventricular tachycardia (very common)
  • Headache, dizziness/light-headedness, apprehension, nausea (common)
  • Severe hypotension, asystole/cardiac arrest (sometimes fatal), bronchospasm, respiratory failure, apnoea/respiratory arrest (frequency not known)

Interactions

  • Dipyridamole is a known inhibitor of adenosine uptake and may potentiate its action — adenosine should not be administered to patients receiving dipyridamole; if use is essential, stop dipyridamole 24 hours beforehand or greatly reduce the adenosine dose
  • Methylxanthines — IV aminophylline or theophylline (50–125 mg by slow intravenous injection) have been used to terminate persistent side effects
  • Use with caution in atrial fibrillation or flutter, especially with an accessory bypass tract, as conduction down the anomalous pathway may increase

Clinical monograph

How it works

It activates cardiac A1 adenosine receptors, transiently slowing or blocking conduction through the atrioventricular node and interrupting re-entry circuits that depend on the AV node.

Prescribing in practice

  • Must be given as a rapid bolus into a large proximal vein followed by an immediate saline flush, with continuous ECG and resuscitation facilities available, because transient asystole, bradycardia and a brief but distressing flushing/chest-tightness reaction are expected.
  • Avoid in second- or third-degree AV block, sick sinus syndrome and asthma or COPD where it may precipitate bronchospasm, unless a functioning pacemaker is present.
  • Effect is markedly potentiated by dipyridamole and antagonised by theophylline, aminophylline and caffeine, so the response and risk profile change with these agents.

Monitoring

Use continuous ECG and blood pressure monitoring with a rhythm strip running through administration to capture the conversion and any transient pauses.

Counselling the patient

  • Warn the patient they may briefly feel flushing, chest pressure or a sense of impending doom that passes within seconds.
  • Have resuscitation equipment and a defibrillator immediately to hand before dosing.
  • Document the rhythm strip as it can be diagnostically useful even if the tachycardia does not convert.

Evidence & guidelines

Adenosine is the recommended first-line pharmacological agent for haemodynamically stable regular narrow-complex SVT in Resuscitation Council UK and NICE-endorsed tachycardia algorithms.

Reference: NICE; ESC SVT Guidelines 2019; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

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Curated clinical cross-links plus same-class fallbacks.

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Adenosine is a core drug in the following exam-focused workups on our sister siteReviseMRCEM.

MRCEM Primary / Intermediate / OSCE candidates: each pathway includes exam-style questions, RCEM/NICE citations, and FAQ summaries.