In the reverse reaction, vitamin K 2,3-epoxide is reduced to vitamin K and possibly to vitamin K hydroquinone by 1,4-dithiothreitol, which is oxidized to a disulfide; some other dithiols and 4-butanethiol can also act. Inhibited strongly by warfarin [cf. EC 1.1.4.2 vitamin-K-epoxide reductase (warfarin-insensitive)].