A 61-year-old man comes to the hospital due to 2 days of right leg swelling. He recently flew back to the United States from Japan, where he was visiting his daughter who is spending a semester abroad. The patient has a medical history of hypertension and hyperlipidemia. Temperature is 37.2 C (99 F), blood pressure is 136/70 mm Hg, and pulse is 90/min. Pulse oximetry shows 99% on room air. Cardiopulmonary examination is within normal limits. There is tenderness and swelling of the right lower extremity up to the mid thigh. Laboratory studies, including prothrombin time and activated partial thromboplastin time, are normal. Venous doppler reveals an occluding thrombus in the right femoral and popliteal veins. The patient is started on rivaroxaban. This drug inhibits which of the following?

Question

A 61-year-old man comes to the hospital due to 2 days of right leg swelling.  He recently flew back to the United States from Japan, where he was visiting his daughter who is spending a semester abroad.  The patient has a medical history of hypertension and hyperlipidemia.  Temperature is 37.2 C (99 F), blood pressure is 136/70 mm Hg, and pulse is 90/min.  Pulse oximetry shows 99% on room air.  Cardiopulmonary examination is within normal limits.  There is tenderness and swelling of the right lower extremity up to the mid thigh.  Laboratory studies, including prothrombin time and activated partial thromboplastin time, are normal.  Venous doppler reveals an occluding thrombus in the right femoral and popliteal veins.  The patient is started on rivaroxaban.  This drug inhibits which of the following?

Quizplus · Accepted Answer

11ec160b_3bec_0e98_9249_277610e97030_MD0001_00 This patient has right lower extremity proximal deep venous thrombosis (DVT), with his recent long flight from Japan being a possible risk factor. Many patients with DVT receive long-term anticoagulation with warfarin. Alternates include direct factor Xa inhibitors (eg, rivaroXaban, apiXaban), which bind to the active site of factor Xa and prevent thrombin formation. These drugs can be administered orally as monotherapy and do not require laboratory monitoring. They are used for venous thromboembolism treatment as well as for stroke prophylaxis in patients with atrial fibrillation (who are at risk for embolic stroke). (Choice A) Factor VIII replacement (not inhibition) is the mainstay of hemophilia A treatment. (Choice C) Eptifibatide inhibits platelet aggregation and thrombosis by blocking the glycoprotein IIb/IIIa receptor, which is the binding site for fibrinogen. This drug is typically used in acute coronary syndrome and in patients undergoing percutaneous coronary intervention. (Choice D) Ticagrelor binds the adenosine diphosphate (ADP) P2Y12 receptor on platelets, which prevents platelet aggregation by blocking ADP-mediated activation of the glycoprotein IIb/IIIa receptor complex. This drug is also used in acute coronary syndrome and in patients undergoing percutaneous coronary intervention. (Choice E) Dabigatran is an oral direct thrombin inhibitor that inactivates both circulating and clot-associated thrombin. It is also used for treatment of thromboembolic disease and stroke prophylaxis in atrial fibrillation. Educational objective: Rivaroxaban is an oral anticoagulant that directly inhibits factor Xa. It is used in venous thromboembolism and atrial fibrillation. __________ References: New oral anticoagulants: their advantages and disadvantages compared with vitamin K antagonists in the prevention and treatment of patients with thromboembolic events. (http://www.ncbi.nlm.nih.gov/pubmed/26150723)

A 61-Year-Old Man Comes to the Hospital Due to 2