Propafenone (hydrochloride) (SA-79 (hydrochloride)) is a class of anti-arrhythmic medication, which treats illnesses associated with rapid heart beats such as atrial and ventricular arrhythmias. IC50 & Target: Sodium Channel^[1]. In Vivo: Propafenone (hydrochloride) (SA-79 (hydrochloride)) is a classic anti-arrhythmic medication, which treats illnesses associated with rapid heartbeats such as atrial and ventricular arrhythmias. According to the Allergic Rhinitis and its Impact on Asthma (ARIA) treatment guidelines, intranasal anti-histamines are recommended for the first line therapy of mild intermittent, moderate/severe intermittent and mild persistent rhinitis (new classification system for rhinitis). Propafenone works by slowing the influx of sodium ions into the cardiac muscle cells, causing a decrease in excitability of the cells. Propafenone is more selective for cells with a high rate, but also blocks normal cells more than class Ia or Ib. Propafenone differs from the prototypical class Ic antiarrhythmic in that it has additional activity as a beta-adrenergic blocker which can cause bradycardia and bronchospasm^[1].