A nurse is collecting data from a client who is taking warfarin and has an elevated PT/INR. Which of the following medications should the nurse anticipate administering?

A. Disulfiram: Disulfiram is used to discourage alcohol use (causes unpleasant reaction); it does not reverse anticoagulation. B. Protamine: Protamine reverses the effects of heparin, not warfarin. C. Naloxone: Naloxone is an opioid antagonist used for opioid overdose; it does not affect PT/INR. D. Vitamin K: Vitamin K (phytonadione) is the antidote that helps reverse the anticoagulant effects of warfarin and lowers elevated PT/INR.