User:Mr. Ibrahem/Warfarin

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 treat 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 (STEMI) and orthopedic surgery. It is generally taken by mouth, but may also be used by injection into a vein.

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. It is recommended that the effects of warfarin typically 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.

Warfarin first came into commercial use in 1948 as a rat poison. In 1954 it was approved for medical use in the United States. It is on the World Health Organization's List of Essential Medicines. Warfarin is available as a generic medication. The wholesale cost in the developing world is about US$1.12 to 7.20 for a typical month of treatment. In the United States it usually costs less than $25 a month. In 2017, it was the 51st most commonly prescribed medication in the United States, with more than 15 million prescriptions.