Additionally, because the mechanism involves enzymes such as VKORC1, patients on warfarin with polymorphisms of the enzymes may require adjustments in therapy to account if the genetic variant that they have is more readily inhibited by warfarin, thus requiring lower doses.Warfarin first came into large-scale commercial use in 1948 as a rat poison. Warfarin was formally approved for human use by the U.S. Food and Drug Administration to treat blood clots in 1954. In 1955, warfarins reputation as a safe and acceptable treatment was bolstered when President Dwight D. Eisenhower received warfarin following a massive and highly publicized heart attack. Eisenhowers illness kickstarted a transformation in medicine where coronary artery disease, arterial plaques, and ischemic strokes were treated and prevented by using anticoagulants such as warfarin. It is on the World Health Organizations List of Essential Medicines. Warfarin is available as a generic medication. In 2020, it was the 58th most commonly prescribed medication in the United States, with more than 11 million prescriptions. Medical uses
Warfarin is used to decrease the tendency for thrombosis, or as secondary prophylaxis (prevention of further episodes) in those individuals who have already formed a blood clot (thrombus).
Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent stroke in people who have atrial fibrillation, valvular heart disease, or artificial heart valves. Less commonly, it is used following ST-segment elevation myocardial infarction and orthopedic surgery. It is generally taken by mouth, but may also be used intravenously.The common side effect is bleeding. Less common side effects may include areas of tissue damage and purple toes syndrome. Use is not recommended during pregnancy. The effects of warfarin typically should be monitored by checking prothrombin time (INR) every one to four weeks. Many other medications and dietary factors can interact with warfarin, either increasing or decreasing its effectiveness. The effects of warfarin may be reversed with phytomenadione (vitamin K1), fresh frozen plasma, or prothrombin complex concentrate.Warfarin decreases blood clotting by blocking an enzyme called vitamin K epoxide reductase that reactivates vitamin K1. Without sufficient active vitamin K1, clotting factors II, VII, IX, and X have decreased clotting ability. The anticlotting protein C and protein S are also inhibited, but to a lesser degree. A few days are required for full effect to occur, and these effects can last for up to five days.