Heart Home > Amiodarone

How Does It Work?

Amiodarone belongs to a group of medications known as antiarrhythmics. Most antiarrhythmic medications are further categorized using a system known as the Vaughn-Williams classification system. This system divides the medications into four general classes based on how they work.
Amiodarone is considered a Class III antiarrhythmic; however, it has properties of all four classes and therefore works in several different ways. The most important way it works is by its Class III antiarrhythmic actions.
These drugs block potassium channels in the heart, preventing potassium from leaving the cells of the heart muscle. This action prolongs the heart's refractory period, which is the period of time heart cells will not respond to a new electrical signal. By extending the refractory period, amiodarone helps the heart tissue resist any electrical signal that is trying to come through prematurely.

Clinical Effects

In general, amiodarone is a very effective antiarrhythmia medication. However, the actual effectiveness depends on several factors, including:
  • The type and severity of the arrhythmia being treated
  • Whether a person responds to and is able to tolerate the medication
  • Whether other antiarrhythmia medicines are being used.
In clinical trials, 20 percent to 40 percent of people who tolerated and responded to amiodarone well enough to continue treatment for at least a year experienced a recurrence of their arrhythmia.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
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