Antiarrhythmics

Table

Class	Known as	Examples	Mechanism	Clinical uses
Ia	fast-channel blockers-Affect QRS complex	Quinidine Procainamide Disopyramide	(Na+) channel block (intermediate association/dissociation)	Ventricular arrhythmias prevention of paroxysmal Recurrent atrial fibrillation (triggered by Vagus nerve overactivity) procainamide in Wolf Parkinson White (WPW)
Ib- Do not affect QRS complex		Lidocaine Phenytoin Mexiletine Tocainide	(Na+) channel block (fast association/dissociation)	treatment and prevention during and immediately after Myocardial infarction, though this practice is now discouraged given the increased risk of Asystole Ventricular tachycardia Atrial fibrillation
Ic		Flecainide Propafenone Moricizine	(Na+) channel block (slow association/dissociation)	prevents Paroxysmal atrial fibrillation treats Recurrent tachyarrhythmias of abnormal conduction system. contraindicated immediately post-myocardial infarction.
II	Beta-blockers	Propranolol Esmolol Timolol Metoprolol Atenolol Bisoprolol Labetalol	beta blocking Propranolol also shows some class I action	decrease Myocardial infarction mortality prevent recurrence of Tachyarrhythmias
III		Amiodarone Sotalol Ibutilide Dofetilide Dronedarone E-4031	K+ channel blocker Sotalol is also a beta blocker Amiodarone has Class I, II, and III activity	In Wolf Parkinson White (WPW) (sotalol:) Ventricular tachycardias and Atrial fibrillation (Ibutilide:) Atrial flutter and Atrial fibrillation
IV	slow-channel blockers	Verapamil Diltiazem	Ca2+ channel blocker	prevent recurrence of Paroxysmal supraventricular tachycardia reduce Ventricular rate in patients with Atrial fibrillation
V		Adenosine Digoxin Magnesium sulfate	Work by other or unknown mechanisms (Direct nodal inhibition).	Used in supraventricular arrhythmias, Or in the case of magnesium sulfate, used in torsade de pointes.

See Also

• Arrhythmias (DDX)
• Atropine
• Isoproterenol

References

• Katzung & Trevor's Pharmacology

Authors

Ross Donaldson