Anatomical Therapeutic Chemical Classification System
The presence of vitamin K (i.e. vitamin K or substances with vitamin K activity) is essential for the formation within the body of prothrombin, factor VII, factor IX and factor X. Lack of vitamin K leads to an increased tendency to haemorrhage. When an antidote to an anticoagulant is necessary it is essential to use vitamin K1 itself, as vitamin K analogues are much less effective.