Warfarin is the most greatly used anticoagulant in the UK. It is taken orally, and works by inhibiting the production of vitamin K dependent prothrombin, Factor VII and Factor X [29]. This means there is less Factor VII available to bind with tissue factor so not as many tissue factor complexes form [30]. The reduction in Factor X means less Thrombin can be converted from Prothrombin, leading to fewer blood clots forming. Although extremely effective in reducing VTE, warfarin can lead to some side effects such as Hemorrhage, Osteoporosis and Purple toe syndrome [31]. But if it is used appropriately, Warfarin can be a low-costing and effective anticoagulant [32]. Warfarin causes problems due to the wide variation in dosage requirements in patients
