Antiarrhythmics

Antiarrhythmic medications help stop an arrhythmia, prevent it from returning, or slow the heart rate when it becomes too fast.
They are grouped into four main classes:

Class I: act on sodium channels
Class II: beta-blockers
Class III: act on potassium channels
Class IV: calcium channel blockers

Classes II and IV are described in their respective sections:
→ Read: Beta-blockers
→ Read: Calcium channel blockers

Here, we present the most commonly used medications from Classes I and III.

Class I :

Example: flecainide (Tambocor™), propafenone (Rythmol™)

These medications block the entry of sodium ions into heart cells.
This helps stop an arrhythmia or maintain a regular rhythm.

Two ways of using these medications

As needed — “pill in the pocket”
Used by people who experience occasional and symptomatic arrhythmia episodes.
When an episode occurs, a single dose of a few tablets can help restore the normal rhythm.
Regular daily treatment
Daily use is also possible.
Flecainide and propafenone are usually taken 2 to 3 times per day.

Most common side effects

Dizziness
Nausea
Propafenone may sometimes cause an unpleasant taste in the mouth.

Class III

Examples : sotalol (Sotacor™), amiodarone (Cordarone™)

These medications block the exit of potassium ions from heart cells, helping to stop an arrhythmia or keep the rhythm regular.

Although they belong to the same class, their profiles are quite different.

1- Sotalol

In addition to its action on potassium channels, sotalol also has an effect similar to beta-blockers.

Usually taken twice daily
Most common side effects: fatigue, dizziness

Sotalol is used exclusively to treat arrhythmias.

2- Amiodarone

Amiodarone is a versatile medication: it has properties of Classes I, II, III, and IV, which explains its effectiveness for many types of arrhythmias.

Usually taken once a day
At the beginning of treatment, a higher dose is often used to reach the desired effect more quickly, then the dose is reduced.

Common side effects