Vitamin K3-d8 is a deuterated derivative of Vitamin K3, and Vitamin K3-d8, like Menadione (Vitamin K3), is a synthetic naphthoquinone lacking the isoprenoid side chain and intrinsic biological activity; however, Vitamin K3-d8 can be enzymatically converted into active Vitamin K2 (menaquinone) following in vivo alkylation, supporting research into vitamin K metabolism, biochemical labeling studies, and isotope-tracer investigations in metabolic and nutritional sciences.