Adenosine Dosing for Supraventricular Tachycardia
For adults with SVT, administer adenosine 6 mg IV as a rapid bolus followed immediately by a saline flush; if unsuccessful after 1-2 minutes, give 12 mg IV (may repeat 12 mg once more if needed). For children, use 0.1 mg/kg IV (maximum 6 mg) as the first dose, followed by 0.2 mg/kg (maximum 12 mg) if the initial dose fails.
Adult Dosing
The most recent AHA guidelines establish a clear dosing protocol 1, 2:
- First dose: 6 mg rapid IV push, followed immediately by a 20 mL normal saline flush 2
- Second dose: 12 mg IV push if no response within 1-2 minutes 1, 2
- Third dose: May repeat 12 mg once more if needed 2
Critical administration technique: Adenosine must be given as a rapid bolus injection as close to the heart as possible (use the most proximal IV site available), followed immediately by a rapid saline flush 2, 3. The drug has an extremely short half-life of less than 10 seconds, making rapid administration essential for efficacy 4.
Recent Evidence on Initial Dosing
Emerging data suggests starting with 12 mg may be more effective 5, 6:
- A 2025 prehospital study of 11,245 patients found that an initial 12 mg dose was associated with 65% increased odds of patient improvement compared to 6 mg (OR: 1.65,95% CI: 1.49-1.82) 5
- The 12 mg initial dose resulted in 28% lower odds of hospital admission (OR: 0.72,95% CI: 0.59-0.87) 5
- Another 2025 ED study showed 12 mg had significantly higher conversion rates than 6 mg (54.2% vs. 40.6%, p = 0.03) 6
- Complications were rare and similar between dosing regimens 5
However, current AHA guidelines still recommend starting with 6 mg 1, 2, and this remains the standard of care until guidelines are formally updated.
Pediatric Dosing
The 2025 AHA/AAP Pediatric Advanced Life Support guidelines provide weight-based dosing 7, 8:
- First dose: 0.1 mg/kg IV/IO rapid bolus (maximum 6 mg) 7, 8
- Second dose: 0.2 mg/kg IV/IO rapid bolus (maximum 12 mg) if no response within 30 seconds 7, 3
Administration technique for children: Use a 2-syringe technique with immediate rapid flush of 5-10 mL normal saline (up to 20 mL may be helpful in older children) 3. Adenosine may be given intraosseously if IV access has not been achieved 3.
Pediatric Dosing Considerations
Research suggests the initial pediatric dose may need optimization 9:
- A study of 85 children found only 36.4% responded to 100 mcg/kg (0.1 mg/kg), while 64.5% responded cumulatively to 200 mcg/kg (0.2 mg/kg) 9
- The median effective dose was 200 mcg/kg (0.2 mg/kg) 9
- Children with pre-excitation required significantly higher doses (220.8 mcg/kg vs. 177.2 mcg/kg, p = 0.039) 9
Despite this, current guidelines recommend starting at 0.1 mg/kg 7, 8, as this approach allows for dose escalation while minimizing risk in the initial attempt.
Critical Safety Considerations
- Second- or third-degree AV block (unless pacemaker present)
- Sick sinus syndrome or symptomatic bradycardia (unless pacemaker present)
- Known asthma or bronchospastic lung disease
- Known hypersensitivity to adenosine
Essential precautions 1, 2, 3:
- Continuous ECG monitoring is mandatory during administration 3
- A defibrillator must be immediately available 3, 11
- Adenosine can precipitate atrial fibrillation, which may conduct rapidly in patients with Wolff-Parkinson-White syndrome, potentially causing ventricular fibrillation 11
- Reduce dose in post-cardiac transplant patients (consider starting with 1 mg IV) 1, those taking dipyridamole or carbamazepine, and when administered via central line 2
Common but transient side effects (lasting <60 seconds) 4, 12:
- Flushing, chest discomfort, dyspnea, headache (occur in approximately 30-36% of patients) 11, 12
- Transient AV block is expected and therapeutic 3
Efficacy Data
Adenosine demonstrates high efficacy for SVT involving the AV node 11, 12:
- Terminates 90-95% of orthodromic AVRT cases 11
- Cumulative response rates: 57.4% after 6 mg, 93.4% after subsequent 12 mg dose 12
- Average time to termination: 30 seconds after injection 12
- Overall success rates in children: 85-100% for AV nodal-dependent tachycardias 13
Important limitation: Early recurrence of tachycardia occurs in approximately 25-33% of patients after successful conversion 13, 14, which may necessitate additional antiarrhythmic therapy to prevent reinitiation 11.