Pilsicainide hydrochloride (SUN-1165) is an orally active sodium channel blocker and potent class Ic antiarrhythmic agent[2].In Vitro: Pilsicainide hydrochloride (SUN-1165) (10-200 μg/mL) decreases peak amplitude of the net inward current in a dose-dependent manner with an IC50 of 29.2 ± 22.9 μg/mL in levo-thyroxine (T4)-treated rat atrial cells.In Vivo: Pilsicainide hydrochloride (SUN-1165) (2 mg/kg; i.v.; once) decreases the conduction velocity in T4-treated rat atrium by decreasing the Max dV/dt and net inward current.