Antiarrhythmic Classification
Class I
Fast sodium (Na) channel blockers
Ia – Quinidine, procainamide, disopyramide (depress phase 0, prolonging repolarization)
Ib – Lidocaine, phenytoin, mexiletine (depress phase 0 selectively in abnormal/ischemic tissue,
shorten repolarization)
Ic – Flecainide, propafenone, moricizine (markedly depress phase 0, minimal effect on repolarization)
Class II
Betablockers
- Propranolol (decreases slope of phase 4)
- Esmolol (decreases slope of phase 4)
- Timolol (decreases slope of phase 4)
- Metoprolol (decreases slope of phase 4)
- Atenolol (decreases slope of phase 4)
Class III
Potassium(K) channel blockers
- Amiodarone (prolongs phase 3; also acts on phases 1, 2, and 4)
- Sotalol (prolongs phase 3, decreases slope of phase 4)
- Ibutilide (prolongs phase 3)
- Dofetilide (prolongs phase 3)
Class IV
Slow calcium (Ca) channel blockers
- Verapamil (prolongs phase 2)
- Diltiazem (prolongs phase 2)
Class V
Variable mechanism
- Adenosine
- Digoxin
- Magnesium sulfate