What is the recommended dose of adenosine (adenosine) for treating supraventricular tachycardia (SVT)?

Adenosine Dosing for Supraventricular Tachycardia

The recommended initial dose of adenosine for treating supraventricular tachycardia (SVT) is 6 mg given as a rapid intravenous bolus, followed by up to two subsequent doses of 12 mg if the initial dose is ineffective. 1

Dosing Protocol

• Initial dose: 6 mg rapid IV bolus (administered over 1-2 seconds) 1
• Follow immediately with a rapid saline flush to ensure the medication reaches the central circulation quickly 1
• If no response within 1-2 minutes: Administer 12 mg rapid IV bolus 1
• If still no response after another 1-2 minutes: May repeat the 12 mg dose once more 1
• Maximum total dosing: Up to 24 mg has been reported as safe in clinical practice 1

Administration Technique

• Administer into IV as proximal or as close to the heart as possible 1
• Use rapid bolus injection followed by immediate saline flush 1
• Central administration requires lower doses than peripheral administration 2
  • If administering centrally (via central venous catheter), consider starting with 3 mg 2

Special Considerations

• Route of administration affects dosing:

  • Central venous administration: Consider lower initial dose (3 mg) as central administration is more effective at lower doses 2
  • Peripheral administration: Standard dosing applies 2

• Recent evidence suggests that a higher initial dose (12 mg) may be associated with:

  • Less need for redosing (25% vs 48% with 6 mg initial dose) 3
  • Greater rates of patient improvement 3
  • Lower rates of hospital admission 3
  • Similar safety profile to 6 mg dosing 3

Mechanism and Effects

• Adenosine selectively blocks AV nodal conduction, making it ideal for terminating AV nodal re-entrant tachyarrhythmias 1
• Extremely short half-life (<10 seconds) allows for rapid dose titration if needed 4
• Will terminate arrhythmias dependent on the AV node but has no effect on ventricular tachycardia 4

Potential Adverse Effects

• Common side effects (usually transient, lasting <60 seconds):
  • Flushing, chest discomfort/pain, dyspnea 1, 4
  • Transient AV block 1
• Rare but important adverse effects:
  • Bronchospasm (caution in asthmatics) 1
  • Transient complete heart block (must be given in monitored environment) 1
  • Initiation of atrial fibrillation (1-15% of cases) 1

Contraindications and Cautions

• Use with caution in patients with:
  • Severe asthma (risk of bronchospasm) 1
  • Pre-excited atrial fibrillation (risk of accelerated ventricular response) 1
• Drug interactions:
  • Enhanced effect with dipyridamole 1
  • Reduced effect with theophylline 1
  • Higher rates of heart block when used with carbamazepine 1

Treatment Algorithm for SVT

1. Ensure patient is hemodynamically stable 1
2. Try vagal maneuvers first (Valsalva, carotid sinus massage if no carotid bruit) 1
3. If vagal maneuvers fail, administer adenosine per protocol above 1
4. If adenosine fails:
   • Consider IV beta-blockers (metoprolol, propranolol) or calcium channel blockers (diltiazem, verapamil) for stable patients 1
   • Avoid verapamil in patients who have received beta-blockers or have Wolff-Parkinson-White syndrome 1
5. For hemodynamically unstable patients or when pharmacological therapy fails:
   • Perform synchronized cardioversion 1

Pediatric Considerations

• Pediatric dosing:
  • Initial dose: 0.1 mg/kg 5
  • If no response: Increase to 0.2 mg/kg for second and third doses 5
  • Maximum dose: 0.25 mg/kg 6
• Effective in terminating SVT in children with similar safety profile to adults 5