phytonadione-A form of vitamin K, known as vitamin K₁. It can be obtained from plants and can be used as an intramuscular vitamin K source in the clinical setting, for emergency treatment of haemorrhage. Phytonadione can be converted in the body to the active form of vitamin K. Since vitamin K is fat-soluble, it needs bile for intestinal absorption.

Note: Menadione and its derivatives are known as vitamin K₃. Although menadione is fat- soluble, menadione bisulfite sodium (a derivative) is water-soluble and therefore, doesn't require bile for intestinal absorption