Phytonadione (vitamin K)
An injectable form of vitamin K1 that helps the liver make clotting factors. It reverses bleeding problems from warfarin-type blood thinners or low vitamin K, and it is given to newborns to prevent bleeding.
An injectable form of vitamin K1 that helps the liver make clotting factors. It reverses bleeding problems from warfarin-type blood thinners or low vitamin K, and it is given to newborns to prevent bleeding.
Phytonadione works the same way as the vitamin K found naturally in the body. In the liver, vitamin K helps an enzyme finish building four clotting factors, known as factors II, VII, IX, and X. That final step switches the factors on, and the liver then releases them into the blood, ready to help form clots. Blood thinners such as warfarin interfere with vitamin K, so a dose of vitamin K lets the liver make working clotting factors again.
Because the liver has to build new clotting factors, it does not work right away. Given into a vein, its effect can usually be detected within an hour or two, bleeding is usually controlled within 3 to 6 hours, and clotting tests often return to normal in 12 to 14 hours. In people who already have enough vitamin K, it has almost no effect. Too much can bring back the clotting risk that a blood thinner was treating, and it can make warfarin work less well for a while when it is restarted.
Phytonadione is vitamin K1 given as a shot to treat bleeding problems caused by a lack of working vitamin K. The liver needs vitamin K to make several clotting factors, so without enough of it, blood clots too slowly and bleeding is more likely. The shortage can come from coumarin blood thinners such as warfarin, from some antibiotics or salicylates, or from conditions that keep the body from absorbing vitamin K, such as blocked bile flow, celiac disease, ulcerative colitis, or cystic fibrosis. It is also used to prevent and treat vitamin K deficiency bleeding in newborn babies.
It is given by a doctor or nurse as an injection under the skin, into a muscle, or into a vein, often as a single dose with more given depending on the response. The label prefers the injection under the skin, because severe allergic reactions have happened with the muscle and vein routes. Newborns get a dose within one hour of birth, ideally from a product made without the preservative benzyl alcohol. It does not counteract the blood thinner heparin, and its safety and effectiveness in children aged 6 months to 17 years have not been established.
People may notice flushing, sweating, dizziness, a change in taste, a fast heartbeat, or pain and swelling where it was injected. The label's most serious warning is a severe, sometimes fatal allergic reaction during or right after a dose into a vein or muscle, with trouble breathing, chest pain, bluish skin, low blood pressure, or collapse. Skin reactions such as itchy patches or hard, scar-like areas can appear from 1 day to a year later. In newborns, the benzyl alcohol preservative can cause a deadly breathing and body-chemistry problem called gasping syndrome, and too much vitamin K can cause jaundice.
This is the boxed warning, the warning the FDA label prints first.
IV and IM injection have caused fatal hypersensitivity reactions, including anaphylaxis, during or right after the dose, even when diluted and on the first dose. Give it subcutaneously unless that route is not feasible and the serious risk of IV or IM use is justified.
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