MS-2720

A 57-year-old man is prescribed warfarin for his atrial fibrillation. The doctor explains that this is to reduce his risk of a stroke, by preventing clots from forming in his heart. The same man is admitted to the hospital some months later for an upper gastrointestinal bleed, and the medical team seeks to reduce his bleeding by giving him vitamin K.

What is the mechanism of action of this reversal agent?