A 68-year-old man with type 2 diabetes mellitus comes to the physician because of a 5-month history of episodic palpitations, dizziness, and fatigue. His pulse is 134/min and irregularly irregular, and his blood pressure is 165/92 mm Hg. An ECG shows a narrow complex tachycardia with absent P waves. He is prescribed a drug that decreases the long-term risk of thromboembolic complications by inhibiting the extrinsic pathway of the coagulation cascade. The expected beneficial effect of this drug is most likely due to which of the following actions?

Question

Quizplus · Accepted Answer

Eductional Objective: This patient's anticoagulant, warfarin, acts by inhibiting vitamin K epoxide reductase. The result is decreased production of reduced vitamin K, the cofactor required by gamma-glutamyl carboxylase to activate the precursors of clotting factors II, VII, IX, and X. Without gamma-carboxylation, these vitamin K-dependent clotting factors cannot bind calcium or membrane phospholipids to achieve hemostasis.

A 68-Year-Old Man with Type 2 Diabetes Mellitus Comes to the Physician