Which medication is a blood thinner?

• A. Lisinopril
• B. Nitroglycerin (NTG)
• C. Coumadin (Warfarin)
• D. Eliquis (Apixaban)

Answer: (C)

Blood thinners, or anticoagulants, work by interrupting the body's ability to form clots. Warfarin is a classic example: it blocks vitamin K recycling, which lowers the production of several clotting factors (II, VII, IX, X) and slows the coagulation process throughout the body. This makes the blood less likely to clot. Nitroglycerin relieves chest pain by vasodilation and does not affect clotting, while lisinopril is an antihypertensive. Apixaban also reduces clotting by directly inhibiting factor Xa, so it is a blood thinner too, but warfarin is the best-known representation in many educational contexts.