Guide To Antiarrhythmics

OVERVIEW

This page provides a clear organized guide to the antiarrhythmic medications that are used to control the cardiac rhythm. There are few different categories of these medications:

  • Class I: Sodium channel blockers 
    • Class IA
    • Class IB
    • Class IC
  • Class II: Beta-blockers
  • Class III: Potassium channel blockers
  • Class IV: Calcium channel blockers
CLASS IA

Mechanism

These medications are sodium channel blockers. They bind to the fast sodium channels and block their activity (stoping depolarization/phase O of the cardiac cell electrical potential).

Net effect

  • Slow/block conduction 
  • Increase AP duration 

Important uses

Side effects to consider

Torsades de pointes

Examples

Quinidine, Procainamide, Disopyramide 

CLASS IB

Mechanism

These medications are sodium channel blockers. They bind to the fast sodium channels and block their activity (stoping depolarization/phase O of the cardiac cell electrical potential).

Net effect

  • Slow/block conduction 
  • Decrease AP duration 
  • Preferentially affect ischemic/depolarized tissues. 

Important uses

Side effects to consider

Examples

Lidocaine, Mexiletine.

CLASS IC

Mechanism

These medications are sodium channel blockers. They bind to the fast sodium channels and block their activity (stoping depolarization/phase O of the cardiac cell electrical potential).

Net effect

  • Slow/block conduction 
  • No effect AP duration 

Important uses

Side effects to consider

Examples

CLASS II

Mechanism

These medications are BETA-BLOCKERS. They decrease cAMP and decrease calcium currents in cells by bidding to beta-1 receptors on cardiac cells. 

Net effect

  • Slow heart rate (decrease SA and AV nodal activity)
  • Increase PR interval (because of decreased AV node activity)

Important uses

Side effects to consider

Examples

CLASS III

Mechanism

These medications are POTASSIUM CHANNEL BLOCKERS. 

Net effect

  • Increased AP duration 
  • Increased resting potential 
  • Increased QT interval

Important uses

Side effects to consider

Examples

CLASS IV

Mechanism

These medications are CALCIUM CHANNEL BLOCKERS

Net effect

  • Decreased conduction velocity 
  • Increased PR interval 
  • Increased resting potential

Important uses

Side effects to consider

Examples

Verapamil, diltiazem.

Page Updated: 05.07.2017