Propafenone ( proe-pa-FEEN-none)(brand name Rythmol®) is a class Ic anti-arrhythmic medication. It is used in the treatment of atrial and ventricular arrhythmias.

It works by slowing the influx of sodium ions into the cardiac muscle cells, causing a decrease in excitablity of the cells.

Propafenone is metabolized primarily in the liver. Because of its short half-life, it requires dosing two or three times daily to maintain steady blood levels. The long-term safety of propafenone is unknown. Because it is structurally similar to another dangerous anti-arrhythmic medicine, flecainide, caution should be exercised in its use. Flecainide has been shown to increase the occurrence of dangerous arrhythmias, primarily in patients with underlying heart disease.