What is the antidote for warfarin?

Vitamin K is the antidote for warfarin, a commonly used anticoagulant medication. Warfarin works by inhibiting vitamin K-dependent clotting factors, which are essential for blood coagulation. When someone's INR (International Normalized Ratio) becomes too high due to warfarin, leading to an increased risk of bleeding, administering vitamin K helps to restore the levels of these clotting factors, effectively reversing the anticoagulant effects of warfarin. By promoting the synthesis of clotting factors that require vitamin K, the body can regain its ability to form blood clots and reduce the risk of bleeding complications.

The other options provided do not have a role in reversing the effects of warfarin. Activated charcoal is used to absorb certain poisons or drugs in the gastrointestinal tract, naloxone is an opioid antagonist used in opioid overdoses, and flumazenil is a benzodiazepine antagonist. None of these options directly interact with the clotting mechanism affected by warfarin or are appropriate for its reversal.