Which of the following does NOT enhance the anticoagulant effect of Warfarin?

Explanation

Phenylbutazone is known to increase the anticoagulant effect of Warfarin by displacing it from plasma proteins. In contrast, Vitamin K and Rifampicin do not potentiate Warfarin's action; Vitamin K actually antagonizes it by promoting clotting factor synthesis, and Rifampicin induces hepatic enzymes that increase Warfarin metabolism, reducing its effect. Therefore, both Vitamin K and Rifampicin do not enhance Warfarin's anticoagulant activity.