What is the administration protocol for amiodarone (antiarrhythmic medication) in a patient with cardiac arrest who is unresponsive to initial defibrillation attempts and has a shockable rhythm, such as ventricular fibrillation or pulseless ventricular tachycardia?

Amiodarone Administration During Cardiac Arrest

For shock-refractory ventricular fibrillation or pulseless ventricular tachycardia, administer 300 mg IV/IO as a rapid bolus after failed defibrillation attempts, followed by a second dose of 150 mg IV/IO if the arrhythmia persists. 1, 2, 3

When to Administer Amiodarone

Amiodarone should only be given after the patient has already received:

• High-quality CPR with minimal interruptions 1
• Multiple defibrillation attempts (at least 1 shock, typically after 2-3 failed shocks) 1, 2
• Epinephrine administration 2, 4

The drug is specifically indicated for shock-refractory VF/pulseless VT—meaning the arrhythmia persists or recurs after initial defibrillation. 1

Dosing Protocol

Initial dose: 300 mg IV/IO administered as a rapid bolus 1, 2, 3

Second dose (if needed): 150 mg IV/IO if VF/pulseless VT persists after the initial dose 1, 2, 3

Critical timing consideration: Do not exceed these doses during the cardiac arrest itself—only one 150 mg supplemental dose should be given during active resuscitation. 2, 3

For breakthrough episodes of VF or hemodynamically unstable VT during resuscitation, the 150 mg supplemental dose should be mixed in 100 mL of D5W and infused over 10 minutes to minimize hypotension. 1, 3

Administration Technique

Route: Intravenous (IV) or intraosseous (IO) 1, 2, 3

Preparation: The polysorbate-based formulation is available in concentrated form (50 mg/mL) for rapid administration during cardiac arrest, which is practical for the emergency setting. 1, 3 The captisol-based formulation comes only as a premixed infusion and is impractical for rapid bolus administration during arrest. 1

Vascular access: Administer through a central venous catheter whenever possible, though peripheral access is acceptable during active resuscitation when time is critical. 3 Recent evidence suggests undiluted amiodarone can be administered into a vein located as centrally as possible without unmanageable hemodynamic side effects. 5

Critical Pitfalls to Avoid

Do not delay CPR or defibrillation to establish vascular access for amiodarone. Both CPR and timely defibrillation are associated with improved survival, while antiarrhythmic drugs have not been demonstrated to increase long-term survival or favorable neurological outcomes. 1

Do not administer amiodarone before attempting defibrillation and giving epinephrine. The drug is a Class IIb recommendation (benefit-to-risk ratio less well established) and should only be considered after primary interventions have failed. 1, 2

Monitor for hypotension, which occurs in approximately 26% of patients and is the most common adverse effect leading to discontinuation. 2, 4 This is primarily attributed to vasoactive solvents in the IV formulation. 2 When possible, administer vasopressors before amiodarone to prevent hypotension. 2

Watch for bradycardia, which occurs in approximately 4.9% of patients on IV amiodarone. 2 Monitor for heart block and AV conduction delays. 2, 4

Evidence Quality and Realistic Expectations

While amiodarone improves short-term outcomes like return of spontaneous circulation (ROSC) and survival to hospital admission compared to placebo, no antiarrhythmic drug has been shown to increase long-term survival or improve neurological outcomes after cardiac arrest. 1, 6 The primary objective is to facilitate successful defibrillation and reduce recurrent arrhythmias, not to pharmacologically convert VF/pulseless VT to an organized rhythm. 1

Recent evidence comparing 300 mg versus 450 mg total doses showed that 300 mg was associated with higher ROSC rates at ED arrival (30.8% vs 24.2%), though differences in survival to discharge did not reach statistical significance. 7 This supports the guideline recommendation of 300 mg initially with only one 150 mg supplemental dose if needed.

Alternative Agent

If amiodarone is unavailable, lidocaine may be considered as an alternative with an initial dose of 1.0 to 1.5 mg/kg IV/IO and a second dose of 0.5 to 0.75 mg/kg IV/IO if required. 1 Both drugs have similar evidence profiles for improving short-term outcomes in witnessed arrests where time to drug administration is shorter. 1