This is a high-yield question that is often asked on exams and clinical rotations.  This mnemonic helps you remember which vitamin K-dependent factors warfarin affects. ⁠ Warfarin, brand name Coumadin, is an anticoagulant that acts by inhibiting the synthesis of vitamin K-dependent clotting factors, which include Factors II, VII, IX, and X, and the anticoagulant proteins C and S.⁠