Moricizine-d 8 (Hydrochloride) is the deuterium labeled Moricizine Hydrochloride. Moricizine Hydrochloride is an orally active Class I antiarrhythmic agent. Moricizine Hydrochloride decreases the maximum rate of phase 0 depolarization; increases rates of phase 2 and 3 repolarization, decreases action potential duration, and decreases effective refractory period.