[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antiarrhythmics](https://durgical.com/en/pharmacology/classes/antiarrhythmics/) › Amiodarone

# Amiodarone

## Antiarrhythmics?

Antiarrhythmics

## High alert?

An error with this medicine can cause serious harm: double checks and protocols are used.

A broad antiarrhythmic for ventricular and atrial arrhythmias. Very effective, but it builds up in tissues and can damage the lungs, liver, thyroid and eyes.

Updated Nov 1, 2026

## Quick facts

**Group**
[Antiarrhythmics](https://durgical.com/en/pharmacology/classes/antiarrhythmics/)

**Target**
Cardiac potassium (hERG/IKr), sodium and L-type calcium channels; β-adrenergic receptors (the L-type calcium channel Cav1.2 is shown)

**Used for**
Recurrent · Atrial fibrillation

**Key effects**
Nausea · Photosensitivity and · Corneal microdeposits

**Monitor**
ECG · Liver enzymes at baseline

**ATC**
C01BD01

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Clinical What the labels mean

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

⇅**Cardiac potassium (hERG/IKr), sodium and L-type calcium channels; β-adrenergic receptors (the L-type calcium channel Cav1.2 is shown)**Amiodarone

ⓘ The figure shows amiodarone bound to the human L-type calcium channel Cav1.2, one of the several cardiac channels it blocks; the hepatitis C drug sofosbuvir is also bound in this structure, which relates to the severe bradycardia seen when the two are combined.

**Target in 3D:** Cardiac potassium (hERG/IKr), sodium and L-type calcium channels; β-adrenergic receptors (the L-type calcium channel Cav1.2 is shown). PDB structure 8FHS (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/8FHS) · Drag to rotate · pinch to zoom

Amiodarone is classed as a class III drug because, with chronic use, it lengthens the action potential and refractory period in all cardiac tissues (longer QT). It also blocks sodium channels at fast rates (class I), has a non-competitive antisympathetic effect (class II) and slows the sinus and AV nodes like calcium channel blockers (class IV). Intravenously it also relaxes vascular smooth muscle and can lower blood pressure.

- Amiodarone blocks potassium channels: longer action potential and QT
- It also blocks sodium and calcium channels and β-adrenergic effects
- The sinus rate falls and AV conduction slows
- Tissue stores build up slowly, so the effect starts and fades over weeks

## Indications

- Recurrent, life-threatening ventricular fibrillation [Cardiac arrest (VF, pulseless VT, asystole, PEA) →](https://durgical.com/en/conditions/cardiac-arrest/)
- Recurrent haemodynamically unstable ventricular tachycardia [Ventricular tachycardia →](https://durgical.com/en/conditions/ventricular-tachycardia/)
- Atrial fibrillation (rhythm control; widely used, though not a labelled US indication) [Atrial fibrillation →](https://durgical.com/en/conditions/atrial-fibrillation/)

## Adverse effects

### Common

- Nausea, constipation and poor appetite
- Photosensitivity and, with long use, blue-grey skin discolouration
- Corneal microdeposits (common, reversible)
- Bradycardia
- Tremor and fatigue
- Hypotension with intravenous use

### Serious (rare, important)

- Pulmonary toxicity (pneumonitis, fibrosis), which can be fatal
- Liver injury, which can be fatal
- Hypothyroidism or hyperthyroidism (it is rich in iodine)
- Optic neuropathy that can lead to loss of vision
- Worsened arrhythmias, including torsades de pointes, and severe bradycardia or AV block
- Peripheral neuropathy

## Contraindications

- Cardiogenic shock
- Sick sinus syndrome, second- or third-degree AV block, or bradycardia with syncope, without a working pacemaker
- Hypersensitivity to amiodarone or iodine

## Key interactions

**Warfarin**
Stronger anticoagulant effect and serious bleeding; the warfarin dose is lowered and the INR checked closely

**Digoxin**
Higher digoxin levels and toxicity; the digoxin dose is reduced or stopped

**Sofosbuvir (hepatitis C)**
Symptomatic, sometimes severe bradycardia

**Other QT-prolonging drugs (class I and III antiarrhythmics, some macrolides, fluoroquinolones, azoles, antipsychotics)**
Higher risk of torsades de pointes; avoided

**Simvastatin, lovastatin and other CYP3A substrates**
Higher statin levels and risk of myopathy

**Beta blockers, verapamil, diltiazem, ivabradine**
Additive bradycardia, sinus arrest and AV block

## What is monitored

- ECG: heart rate, PR, QRS and QT
- Chest X-ray and pulmonary function tests at baseline, then if symptoms appear
- Liver enzymes at baseline and periodically
- Thyroid function at baseline and periodically
- Eye examination if vision changes
- Potassium and magnesium; INR and digoxin levels when combined

## Administration and safety

- Intravenous amiodarone is given by infusion pump, ideally through a dedicated central line, with an in-line filter.
- It irritates peripheral veins (phlebitis); the site is watched closely when a peripheral line is used.
- Long infusions are mixed in glass or polyolefin containers; the drug leaches plasticisers (DEHP) from PVC tubing.
- Hypotension during the infusion is managed first by slowing the infusion.
- The injection contains benzyl alcohol, which is dangerous for neonates.

## Pregnancy and breastfeeding

It crosses the placenta and can cause fetal thyroid problems, slow fetal heart rate and growth restriction, so it is used in pregnancy only when other options fail.

## Nursing care

- Continuous ECG and blood pressure during intravenous use; report bradycardia, AV block, QT prolongation or hypotension.
- Correct low potassium and magnesium before starting, as ordered.
- Ask about new cough or breathlessness, yellow skin or dark urine, visual changes, and signs of an over- or underactive thyroid.
- Teaching: sun protection, avoid grapefruit juice, and tell every prescriber about amiodarone, since interactions last for months.

## Pharmacokinetics

**Absorption**
Slow and variable by mouth; food increases absorption, so it is taken the same way with respect to meals

**Distribution**
Highly protein bound with a huge volume of distribution: it accumulates in fat, liver, lung and other tissues

**Metabolism**
Liver, by CYP3A and CYP2C8, to the active metabolite desethylamiodarone

**Half-life**
Weeks to months, so effects, toxicity and interactions persist long after stopping

**Onset and duration**
Oral antiarrhythmic effect takes days to weeks, even with a loading phase

## Memory aid

Amiodarone hits the organs a doctor checks every visit: lungs, liver, thyroid, eyes and skin ("Blue man with a stiff lung and a strange thyroid"); and it raises the levels of warfarin and digoxin.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does amiodarone affect the thyroid?

It is rich in iodine and alters thyroid hormone metabolism, so it can cause hypothyroidism or hyperthyroidism.

## Which tests are taken before long-term amiodarone?

Chest X-ray and pulmonary function tests, liver enzymes, thyroid function and an ECG.

## What happens to warfarin and digoxin when amiodarone is added?

Both rise: the INR goes up with bleeding risk and digoxin levels increase, so their doses are reduced and levels checked.

## Why do amiodarone's interactions and toxicity last long after it is stopped?

Its half-life is weeks to months because it accumulates in fat and other tissues.

## What is the most common adverse effect of intravenous amiodarone and its first management?

Hypotension; the infusion is slowed first.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/pharmacology/amiodarone/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## What the labels mean

**High alert**
An error with this medicine can cause serious harm: double checks and protocols are used.

## Connections

## Related drugs 5

- [Sotalol](https://durgical.com/en/pharmacology/sotalol/)
- [Lidocaine](https://durgical.com/en/pharmacology/lidocaine/)
- [Digoxin](https://durgical.com/en/pharmacology/digoxin/)
- [Warfarin](https://durgical.com/en/pharmacology/warfarin/)
- [Levothyroxine](https://durgical.com/en/pharmacology/levothyroxine/)

## Related conditions 3

- [Cardiac arrest (VF, pulseless VT, asystole, PEA)](https://durgical.com/en/conditions/cardiac-arrest/)
- [Ventricular tachycardia](https://durgical.com/en/conditions/ventricular-tachycardia/)
- [Atrial fibrillation](https://durgical.com/en/conditions/atrial-fibrillation/)

[← Back to the class: Antiarrhythmics](https://durgical.com/en/pharmacology/classes/antiarrhythmics/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - AMIODARONE HYDROCHLORIDE tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4c149392-a4f0-4e2d-a13f-2b94810005de) (DailyMed (U.S. National Library of Medicine), 2026); [DailyMed - AMIODARONE HYDROCHLORIDE injection, solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0c9ee15a-5741-4aaa-8d80-c7bd2e45822e) (DailyMed (U.S. National Library of Medicine), 2026); [8FHS: Human L-type voltage-gated calcium channel Cav1.2 in the presence of amiodarone and sofosbuvir at 3.3 Angstrom resolution](https://www.rcsb.org/structure/8FHS) (RCSB Protein Data Bank, 2023).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/amiodarone/