A nurse is caring for a client who has deep vein thrombosis and has been on heparin continuous infusion for 5 days. The provider prescribes warfarin PO without discontinuing the heparin. The client asks the nurse why both anticoagulants are necessary. Which of the following statements should the nurse make?

The correct answer is D: Warfarin takes several days to work, so the IV heparin will be used until the warfarin reaches a therapeutic level. Warfarin works by inhibiting the synthesis of vitamin K-dependent clotting factors, which takes time to achieve a therapeutic effect. By continuing the IV heparin, the client is protected against clot formation until the warfarin reaches its full anticoagulant effect. Option A is incorrect as heparin and warfarin do not work together to dissolve clots but have different mechanisms of action. Option B is incorrect as the provider has already prescribed warfarin without discontinuing heparin. Option C is incorrect as IV heparin does not directly increase the effects of warfarin.