A client is being changed from an injectable to an oral anticoagulant. Which of the following is administered orally?

• A. Enoxaparin
• B. Warfarin
• C. Bivalirudin
• D. Lepirudin

Answer: (B)

The key idea is recognizing which anticoagulant is taken by mouth. Warfarin is the oral anticoagulant among commonly used options. It is a vitamin K antagonist given by mouth for long‑term prevention of thrombosis. The other drugs you might encounter here are all parenteral: enoxaparin is a subcutaneous low‑molecular‑weight heparin, while bivalirudin and lepirudin are direct thrombin inhibitors given by intravenous routes. Warfarin’s effect develops gradually because it blocks the synthesis of vitamin K–dependent clotting factors, so you monitor its effect with the INR and often bridge with a parenteral anticoagulant when switching from IV/SC agents to oral therapy until the INR is in the therapeutic range. Also, patients must maintain consistent vitamin K intake and watch for drug and food interactions that can affect warfarin’s effect.