When is the full effect of Warfarin typically achieved?

Warfarin is an anticoagulant medication that works by inhibiting vitamin K-dependent clotting factors, which are produced in the liver. The full effect of Warfarin is achieved typically within 5 to 10 days because its anticoagulant action depends on the reduction of these clotting factors, which have varying half-lives.

Initially, when a patient starts Warfarin, the existing clotting factors remain active and it takes time for them to be cleared from circulation. Factors such as Factor VII, which has a half-life of about 6 hours, deplete faster, while others, like Factor II (prothrombin), can take several days due to its longer half-life of approximately 60 hours. As these factors decrease, the anticoagulant effect of Warfarin becomes more pronounced. Therefore, it generally takes about 5 to 10 days to reach the established therapeutic effect where the risk of thrombosis is significantly reduced.

This ability to achieve the full therapeutic effect within this timeframe explains the correct choice. The other options suggest shorter durations, which do not account for the half-lives of the involved clotting factors and the gradual onset of Warfarin's effects.