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 |
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.
- After Cardiac SurgeryPost-op AF and epicardial pacing: POAF: 30 to 50%, more after valve surgery; peaks around day 2. STS 2026 prevention: oral amiodarone (Class I), beta-blockers or posterior pericardiotomy (IIa). Unstable: cardioversion. Stable: rate or rhythm control, replace K and Mg; anticoagulate by stroke risk once bleeding settles.
- 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
- 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
- Implanted Cardiac Devices: Pacemakers, ICDs and Wearable DefibrillatorsICD shocks: Electrical storm: 3 or more VA episodes in 24 h, at least 5 min apart, each needing an intervention: Sedation, nonselective beta-blocker (propranolol) plus amiodarone, fix triggers (ischemia, K, Mg, HF); ablation if it persists
Practice Rhythm Gallery questions free86 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 the order, the label and your institution's protocols.