Cystamine-d 8 (dihydrochloride) is the deuterium labeled Cystamine (dihydrochloride). Cystamine (dihydrochloride) is the disulfide form of the free thiol, cysteamine. Cystamine is an orally active transglutaminase (Tgase) inhibitor. Cystamine also has inhibition activity for caspase-3 with an IC50 value of 23.6 μM. Cystamine can be used for the research of severals diseases including Huntington's disease (HD).