Andrew a 65 year old male with a history of myocardial infar

Andrew, a 65 year old male with a history of myocardial infarction, is prescribed warfarin. Prothrombin time measures reveal that dose is ineffective. Andrew is queried on his vitamin K supplements. Describe the mechanism by which warfarin decreases blood clot formation. Why Andrew was queried on his vitamin K supplements?

Solution

Warfarin is a blood thinner. Warfarin prevents formation of blood clots. Blood coagulation occurs due to production of insoluble fibrin. This fibrin gets produced from fibrinogen and which inturn gets formed from thrombin. Liver produces vitamin K and which activates production of prothrombin. This prothrombin gets activated into thrombin. Here the warfarin directly acts and resists producation vitamin K from liver and thus checks formation of thrombin from prothrombin. Thus warfarins are considered as vitamin K antagonists. If more the vitamin K supplements taken by a patient, the warfarin intake also to be increased. If lesser the vitamin K production/supplementation, then warfarin intake also to be reduced.