Antiarrhythmic medication helps control and slow the heart rate. Antiarrhythmics work by either slowing the activity of tissue that is initiating electrical impulses too quickly in the heart's natural pacemaker or by slowing the transmission of fast electrical impulses that cause the heart to beat. Antiarrhythmics include several classes of drugs, such as sodium channel blockers, beta-blockers, potassium channel blockers and calcium channel blockers. Other medications used to control heart rate include adenosine and digitalis (also called digoxin and digitoxin). The type of arrhythmia you have determines which medication is prescribed.