Which of the following is a direct oral anticoagulant (DOAC)?

• A. Dabigatran
• B. Heparin
• C. Enoxaparin
• D. Warfarin

Answer: (A)

Direct oral anticoagulants inhibit a specific clotting component directly and are taken by mouth. Dabigatran fits this since it directly inhibits thrombin (factor IIa) and is administered orally. That direct mechanism and oral access distinguish it from the others. Heparin and enoxaparin are given by injection and work by enhancing antithrombin to inhibit thrombin and factor Xa—an indirect approach, not a DOAC. Warfarin blocks vitamin K–dependent clotting factor production in the liver and isn’t a direct inhibitor of a single factor, plus it requires regular INR monitoring. So among the options, dabigatran is the direct oral anticoagulant.