Etripamil Intranasal Dosing for Paroxysmal Supraventricular Tachycardia
The recommended intranasal dose of etripamil for adults with paroxysmal supraventricular tachycardia (PSVT) is 70 mg as an initial dose, with an optional repeat 70 mg dose if symptoms persist 10 minutes after the first dose. 1, 2
Dosing Regimen
- Initial dose: 70 mg intranasal spray administered after attempting a vagal maneuver 1, 2
- Repeat dose: An optional second 70 mg dose may be self-administered if symptoms persist beyond 10 minutes after the first dose 1, 2
- Maximum total dose: 140 mg per episode (two 70 mg doses) 2
Administration Protocol
When patients experience PSVT symptoms, they should follow this sequence:
- Apply an electrocardiographic monitor 1, 3
- Perform a vagal maneuver first (as vagal maneuvers remain a Class I recommendation for acute SVT treatment) 4
- If the vagal maneuver is unsuccessful, self-administer the first 70 mg dose of etripamil 1, 2
- Wait 10 minutes and assess symptom persistence before considering the optional repeat dose 1, 2
Efficacy Timeline
The medication demonstrates rapid onset with clinically meaningful effects:
- Median time to conversion: 17.2 minutes (95% CI: 13.4-26.5 minutes) with the etripamil regimen 2
- Conversion rates at 30 minutes: 64% with etripamil versus 31% with placebo (hazard ratio 2.62, p<0.0001) 2
- Conversion rates at 60 minutes: 70.5% of patients converted to sinus rhythm 1
- Peak pharmacodynamic effect: PR interval prolongation occurs within 4-7 minutes and is sustained for approximately 45 minutes 5
Safety Profile
Etripamil at the 70 mg dose (single or repeat) has been well-tolerated across multiple studies:
- Most common adverse events: Nasal discomfort (23-30%), nasal congestion (13-14%), rhinorrhea (9-13%), and epistaxis (7%) 1, 2
- Severity: Adverse events are predominantly mild to moderate, transient, and localized to the nasal administration site 1, 2
- No serious cardiac events: No bradyarrhythmias, clinically significant AV block, sinus pauses ≥3 seconds, or serious adverse events were reported 6, 1, 2
- Adverse event frequency decreases: With repeated use across multiple PSVT episodes, treatment-emergent adverse event frequencies declined 1
Clinical Context
This dosing recommendation represents a paradigm shift from traditional PSVT management. While current ACC/AHA/HRS guidelines recommend adenosine (Class I, LOE B-R) and synchronized cardioversion for acute PSVT treatment 4, these interventions require medical supervision. Etripamil provides the first self-administered, fast-acting option for terminating PSVT episodes outside healthcare settings 2.
Important Caveats
- No test dose required: Unlike earlier protocols, the NODE-303 study demonstrated safety without mandatory supervised test dosing before first use 1, 3
- AV-nodal dependent PSVT: Etripamil is specifically designed for atrioventricular nodal-dependent PSVT 2, 5
- Atrial fibrillation: Post-hoc analysis showed etripamil also reduced ventricular rate in patients with atrial fibrillation (average maximum reduction 27.4 bpm at 22 minutes), though this requires further study 6
- Pharmacokinetics: Rapid absorption with time to maximum concentration of 5-8.5 minutes and terminal half-life of approximately 2.5-3 hours at the 70 mg dose 5