Antiarrhythmic
Amiodarone (Nexterone)
Also called Nexterone, Cordarone
Indications
- Shock-refractory VF or pulseless VT (ACLS; lidocaine is the alternative)
- Recurrent VF or unstable VT, as a load and infusion
- Stable monomorphic VT or regular wide-complex tachycardia (off-label)
- AF or flutter: rate control when hypotension or HFrEF rules out other drugs, and rhythm control (off-label)
- AF prevention after cardiac surgery (off-label; oral, STS 2026 Class I)
Dosing
Amiodarone drip card and mL/h converterStart: 150 mg over 10 minutes, then 1 mg/min for 6 hours
| Where | Dose |
|---|---|
| Cardiac arrest | Amiodarone: 300 mg IV/IO, then 150 mg (VF/pVT refractory to shocks) |
| Rhythm control | Amiodarone: 150 mg over 10 min, repeat; then 1 mg/min for 6 h, 0.5 mg/min for 18 h |
On the quick cards
Mechanism of action
Amiodarone is classed as Vaughan Williams class III: it blocks the delayed rectifier K⁺ currents (IKr, also IKs), lengthening action potential duration and refractoriness in every cardiac tissue, accessory pathways included. It also blocks inactivated Na⁺ channels (class I), gives noncompetitive α- and β-adrenergic blockade (class II) and blocks L-type Ca²⁺ channels (class IV). After an IV dose the nodal slowing of the class II and IV actions dominates; the full class III effect builds over weeks as tissues load.
Pharmacology
- Cardiovascular: slows the sinus rate and AV conduction, lengthens PR and QT; IV doses vasodilate; little negative inotropy
- Cardiovascular: torsades is rare for the QT change (TdP or new VF in under 2% with IV use, label)
- Endocrine: blocks T4-to-T3 conversion and adds an iodine load; long-term, hypothyroidism up to 10% and hyperthyroidism about 2% (label)
- Respiratory: pneumonitis and fibrosis with long-term use; ARDS in 2% within 48 h of IV therapy (label)
- Liver and other: acute hepatitis during IV loading (polysorbate 80 suspected); corneal deposits, optic neuropathy, photosensitivity, blue-gray skin
Pharmacokinetics
| Onset | IV: minutes to hours; oral: usually 1–3 weeks even with a load (label) |
|---|---|
| Duration | Serum level falls to 10% of peak 30–45 min after an IV load as tissues take it up, hence the infusion |
| Half-life | 9–36 days after IV dosing; 40–55 days on long-term oral therapy (labels) |
| Distribution | Vd about 60 L/kg, stored in fat, muscle, liver, lung and skin; crosses the placenta |
| Protein binding | Over 96% |
| Metabolism | CYP3A and CYP2C8 to active desethylamiodarone, which also accumulates |
| Elimination | Bile and feces; negligible renal, so no kidney dose change |
| Dialysis | Not removed by hemodialysis or CRRT |
Chemistry
- A benzofuran derivative whose diiodophenyl ring resembles thyroxine; 37.3% iodine by weight, about 75 mg per 200 mg tablet (label)
- Highly lipophilic (log P about 7, PubChem) and almost insoluble in water; a weak base (tertiary amine, reported pKa 6.6–9.1); achiral
- Generic IV is 50 mg/mL in polysorbate 80 and benzyl alcohol, solvents thought to add to hypotension; benzyl alcohol carries the neonatal gasping-syndrome warning
- Nexterone premix (1.5 and 1.8 mg/mL) uses sulfobutylether β-cyclodextrin instead and needs no dilution
- Leaches the plasticizer DEHP from PVC tubing, more at high concentrations and slow rates; infusions over 2 h go in glass or polyolefin with D5W, through an in-line filter (label)
Adverse effects and cautions
In the one-pagers
- Rhythm GallerySinus, atrial and junctional: AF with WPW (fast, irregular, wide): no AV-nodal blockers (adenosine, diltiazem, beta-blockers, digoxin, amiodarone). Unstable: cardiovert. Stable: procainamide or ibutilide.
- ACLS Algorithms in BriefCardiac arrest: two tracks: Exam order: shock, CPR, shock, epinephrine, shock, amiodarone or lidocaine. Epinephrine every 3–5 min is about every other 2-minute cycle.
- ACS and STEMIArrhythmias and conduction block after MI: VF or polymorphic VT: Most in the first 48 h: Defibrillate; amiodarone or lidocaine; reperfuse
- Common EMS MedicationsArrest and rhythm drugs: Amiodarone, class III: Shock-refractory VF/pVT; stable VT: Arrest 300 mg, then 150 mg; VT 150 mg over 10 min: If pulse: 2nd/3rd-degree block, cardiogenic shock
- Hypothermia, Heat Stroke and DrowningHypothermic cardiac arrest: No epinephrine below 30 °C (AHA, ERC); ERC: one amiodarone 300 mg for VF, epinephrine every 6–10 min at 30–35 °C
- LVAD BasicsArrhythmias, arrest and transport: Ventricular arrhythmias occur in a third to a half of patients in the first year. Because the LV is drained mechanically, sustained VT or even VF can be tolerated for a time; what fails is the RV, so preload, flow and PI fall and suction follows over minutes to hours. Replace potassium and magnesium, give volume if the LV is small, start amiodarone or lidocaine,
Practice Rhythm Gallery questions free17 exam-style questions with rationales on the topic where Amiodarone comes up most. No account or download needed.
In the algorithms
- Adult Cardiac Arrest
- Tachycardia With a Pulse
- Arrest After Cardiac Surgery
- VT Storm
- Accidental Hypothermia
- Pediatric Cardiac Arrest (PALS)
Other antiarrhythmic drugs
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Sources
- FDA label: Nexterone (2024)
- FDA label: Amiodarone injection, Fresenius Kabi (2025)
- FDA label: Pacerone (2025)
- PubChem: amiodarone
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow your local protocols and medical direction.