A nurse is caring for a client who has a deep vein thrombosis, who received IV anticoagulation therapy for the past 5 days, and now has a new prescription for oral warfarin (Coumadin) in addition to subcutaneous enoxaparin sodium (Lovenox) injections. The client asks the nurse if both medications are necessary. Which of the following is an appropriate response by the nurse?

Choice A rationale Enoxaparin (a low-molecular-weight heparin) and warfarin (a vitamin K antagonist) are anticoagulants that prevent the formation of new fibrin clots or the enlargement of existing ones, but they do not dissolve established clots; that is the function of thrombolytic agents like tissue plasminogen activator. Administering both aims for adequate anticoagulation until warfarin is fully effective. The correct response emphasizes discontinuing enoxaparin when warfarin is therapeutic. Choice B rationale Warfarin, an oral anticoagulant, inhibits vitamin K-dependent clotting factors (II, VII, IX, X), requiring several days to reach a therapeutic effect, which is monitored by the International Normalized Ratio (INR) (therapeutic range typically 2.0–3.0). Enoxaparin, an injectable anticoagulant with immediate onset, is continued concurrently to maintain protection until the INR is therapeutic and adequate anticoagulation is achieved via warfarin alone, a process called bridging. Choice C rationale Enoxaparin and warfarin have distinct mechanisms of action and do not enhance each other's effects synergistically; rather, they inhibit different points in the coagulation cascade. Enoxaparin mainly inhibits Factor Xa, while warfarin inhibits Vitamin K-dependent clotting factor synthesis. They are used together to provide immediate anticoagulation (enoxaparin) while awaiting warfarin's delayed onset. Choice D rationale While patient education is crucial, responding by deferring the client's question is not therapeutic and does not address the client's need for understanding their therapy. The nurse should explain the rationale for concurrent therapy (bridging) and the planned discontinuation of the injectable drug once the oral medication is within its therapeutic range.