Coumadin (warfarin) is an anticoagulant. What vitamin is the antidote for its overdose?

• A. Vitamin A
• B. Vitamin K
• C. Vitamin C
• D. Vitamin D

Answer: (B)

Warfarin, known by its brand name Coumadin, is an anticoagulant medication commonly used to prevent blood clot formation. It works by inhibiting the vitamin K-dependent synthesis of specific clotting factors in the liver, which are crucial for proper blood coagulation. When there is an overdose of warfarin, the risk of bleeding increases significantly, and an antidote is necessary to reverse the effects and restore normal clotting ability.

Vitamin K plays a central role in the body's clotting process because it is required for the synthesis of clotting factors II, VII, IX, and X. Administering vitamin K can help counteract the anticoagulant effects of warfarin by replenishing the body's supply of this vital nutrient. This process allows for the production of the clotting factors that warfarin has inhibited, thus facilitating better coagulation and reducing the potential for serious bleeding complications.

In contrast, vitamins A, C, and D do not have a significant role in the reversal of warfarin's effects, as they do not participate in the same pathways or mechanisms involved in blood coagulation processes influenced by vitamin K. Therefore, vitamin K is the appropriate antidote for warfarin overdoses.