See the DrugPatentWatch profile for Phytonadione
What is phytonadione?
Phytonadione, also called phytomenadione, is the synthetic form of vitamin K1. It functions as a co‑factor for clotting factors II, VII, IX, and X, and is used to reverse vitamin K deficiency or counteract warfarin‑induced anticoagulation.
When do doctors give phytonadione?
The drug is used in two main settings: (1) as an antidote in cases of acute vitamin K antagonist toxicity, such as warfarin overdose; (2) prophylactically in newborns who are at risk for vitamin K deficiency bleeding. It can also be prescribed for patients with malabsorption or chronic liver disease.
How is it administered?
Phytonadione can be given orally, intramuscularly (IM), or intravenously (IV). Oral tablets are common for newborn prophylaxis; IV is preferred when rapid reversal is needed, such as in severe bleeding. IM injections are used when IV access is not available or when a slower, sustained effect is desired.
What are the standard doses?
- Newborn prophylaxis: 1 mg IM or 10 mg oral.
- Antidote for warfarin toxicity: IV doses range from 5 mg up to 15 mg, depending on INR and the patient’s weight, repeated every 6–12 hours until the INR falls below 1.5.
- Oral supplementation for deficiency: 10–30 mg daily, adjusted by the treating clinician.
Can phytonadione cause side effects?
Side effects are uncommon but can include injection site reactions (pain, redness, swelling), hypersensitivity, or, rarely, anaphylaxis. Oral therapy may cause nausea or mild abdominal discomfort.
Is it safe for people with kidney or liver disease?
Yes, phytonadione is metabolized by the liver and cleared renally, but it is generally safe in both hepatic and renal impairment when dosed appropriately. Monitoring INR is essential in these populations.
How does it differ from vitamin K2 (menaquinone)?
Vitamin K1 is absorbed primarily from the diet and supports clotting factor synthesis. Vitamin K2, found in fermented foods, has a longer half‑life and is mainly involved in bone and cardiovascular health. Phytonadione is specifically used to correct clotting deficiencies, not for the bone‑health benefits attributed to K2.
Can phytonadione be taken with other medications?
Because it counteracts warfarin, co‑administration should be carefully managed. Other anticoagulants, such as dabigatran, do not interact with phytonadione. Always inform the prescribing clinician of all medications to avoid interference.
How long does phytonadione stay active in the body?
After IV or IM administration, the plasma half‑life is about 20–40 minutes, but its effect on clotting factors lasts several days as the body synthesizes new proteins. Oral phytonadione has a longer bioavailability window, allowing once‑daily dosing for prophylaxis.
What are the storage and shelf‑life rules?
Store at 15 °C–25 °C (59 °F–77 °F) in a tightly sealed container, away from heat and light. The vial lasts 2–5 years from the date of manufacture if unopened. Once opened, the solution should be used within 24 hours.
Is phytonadione available over the counter?
No. In most countries phytonadione is prescription‑only due to its potent anticoagulant‑modifying effect.
What alternatives exist if phytonadione is unavailable?
- Vitamin K1 oral supplements for non‑emergency deficiency.
- Vitamin K3 (menadione) is rarely used due to toxicity concerns.
- Fresh frozen plasma or prothrombin complex concentrates can provide clotting factors directly when rapid reversal is required.
Do patients ask about its cost or insurance coverage?
Generic phytonadione is inexpensive, and most insurance plans cover it as a standard antidote. The cost for IV administration may be higher due to infusion time and monitoring.
What should patients remember before taking phytonadione?
Discuss all current medications, especially anticoagulants. Report any history of allergic reactions to vitamin K products. If receiving IV therapy, inform the healthcare team about any kidney or liver conditions.