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Vitamin K (Coagulation Factor Synthesis)

Phytomenadione (Vitamin K1)

Brand names: Konakion MM Paediatric, Konakion MM

Phytomenadione (vitamin K1) is the fat-soluble vitamin used to treat or prevent bleeding from vitamin K deficiency, to reverse warfarin over-anticoagulation, and, as a single injection at birth, to prevent vitamin K deficiency bleeding of the newborn.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It is an essential cofactor for hepatic gamma-carboxylation of clotting factors II, VII, IX and X and proteins C and S, restoring synthesis of functional coagulation factors.

Prescribing in practice

  • Intravenous administration carries a risk of severe anaphylactoid reactions, so give slowly and dilute appropriately; use the smaller oral or low-dose intravenous route for warfarin reversal to avoid prolonged warfarin resistance.
  • Onset of effect is not immediate, so for major bleeding it must be combined with a clotting factor concentrate or plasma rather than relied on alone.
  • Excessive correction makes re-anticoagulation with warfarin difficult, so titrate the dose to the degree of reversal required.

Monitoring

Monitor the INR (or relevant coagulation parameters) after administration to confirm adequate but not excessive reversal.

Counselling the patient

  • Explain that vitamin K works over hours rather than instantly.
  • Newborn vitamin K is given to prevent serious bleeding and is routinely recommended.
  • Report any recurrence of bleeding or bruising.

Evidence & guidelines

Vitamin K for reversal of warfarin-related high INR and routine neonatal vitamin K prophylaxis are standard UK practice.

Reference: BCSH Guidelines on anticoagulation reversal; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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