Arrhythmia is irregular heart beat so heart is unable to pump out blood adequately. It can occur at any age, but more common as one grows old. Anti-arrhythmic are used to control arrhythmia. They are classified according to their effects on the electrical behaviour of myocardial cells during activity.

• Class I: membrane-stabilising - procainamide.
• Class II: reduce adrenergic input - beta-blockers.
• Class III: potassium blockers - eg, amiodarone, sotalol.
• Class IV: calcium influx blockers - eg, verapamil (but not dihydropyridines).

Sotalol has both Class II and Class III actions.

• Quinidine
• Procainamide
• Lidocaine (Lignocaine)
• Mexiletine
• Propafenone
• Adenosine
• Amiodarone
• Sotalol
• Verapamil
• Dronedarone