What is the best form of zink as a vitamin?

How exactly does warfarin block the vitamin K cycle?

• I understand how warfarin is metabolized, I get how it's chirality in structure produces a varied strength of the drug. What i don't get is how warfarin blocks/interrupts/negates the Vitamin K Epoxide reductase enzyme. what chemically goes on that allows it? Also, how does blocking the Vitamin K Epoxide enzyme stop coagulant factors because technically i though Vitamin K could still form vitamin K hydroquinone, and therefore facilitate the blood coagulant factors. Because the warfarin blocks that enzyme, there is a prohibitive "force" to the reconversion of Vitamin K Epoxide back to vitamin K, it doesn't stop the vitamin K (taken into the body) to form hydrquinone initially....I am assuming that the coagulant needs to be formed many many times by the recycling process in the Vitamin K Cycle, which no longer occurs with warfarin?

• Answer:

  You're pretty much right on with the concepts in your question - there's really nothing stopping vitamin K from being used once to generate clotting factors; however, clotting factors get used up normally, so the body is constantly making more. However, the point of warfarin treatment is not to completely stop the creation of coagulation factors, only to reduce it. If you completely eliminate all coagulation factors, you quickly bleed to death (in fact, that's how warfarin is used as rat poison). Normally, the supply of vitamin K isn't an issue because the body can keep recycling it using epoxide reductase - with coumadin treatment, the point is basically to make it a limiting factor by balancing the amount of vitamin K that is generated by bacteria or consumed in the diet with the right degree of inhibition. But, as you surmised, a patient can sort of defeat the treatment by eating/injecting a bunch of vitamin K (injected vitamin K is part of the treatment for overdose) .