Vitamin K antagonist

Vitamin K antagonists (VKAs) are a group of substances that reduce blood clotting by reducing the action of Vitamin K. They are used as anticoagulant medications in the prevention of thrombosis, and in pesticides.

Mechanism of action

VKAs work by inhibiting the vitamin K-dependent synthesis of biologically active forms of the clotting factors II, VII, IX and X, as well as the regulatory factors protein C, protein S, and protein Z. This is done by blocking the action of Vitamin K epoxide reductase, which is responsible for the reduction of vitamin K.

Medical uses

VKAs are commonly used in the prevention and treatment of thromboembolic disorders such as deep vein thrombosis and pulmonary embolism. They are also used in the management of atrial fibrillation to reduce the risk of ischemic stroke.

Side effects

The most serious side effect of VKAs is bleeding. Other side effects can include skin rash, hair loss, and liver damage. Patients on VKAs are monitored with the Prothrombin time and the International Normalized Ratio (INR) to ensure that the dose is correct.

Examples

Examples of VKAs include warfarin, acenocoumarol, and phenprocoumon. Warfarin is the most commonly used VKA in the United States.

See also

• Anticoagulant
• Blood clot
• Vitamin K