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Vitamin K — Anticoagulant Reversal / Haemostasis

Phytomenadione (Vitamin K1)

Brand names: Konakion MM

Phytomenadione (vitamin K1) is used perioperatively to reverse vitamin K antagonist anticoagulation and to correct vitamin K-dependent coagulopathy before or around surgery.

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

Phytomenadione is a cofactor for hepatic gamma-carboxylation of clotting factors II, VII, IX and X, restoring synthesis of functional vitamin K-dependent coagulation factors.

Prescribing in practice

  • When given intravenously, infuse slowly and with caution because rapid administration has been associated with severe, occasionally fatal anaphylactoid reactions.
  • For urgent or major bleeding before surgery, vitamin K alone is too slow to restore haemostasis and should be combined with prothrombin complex concentrate as indicated.
  • Choose the route and dose according to urgency and whether future re-anticoagulation is planned, as larger doses can cause prolonged resistance to warfarin.

Monitoring

Monitor INR and clinical bleeding to guide repeat dosing and the timing of any re-anticoagulation after surgery.

Counselling the patient

  • This vitamin K reverses the blood-thinning effect of warfarin before your operation.
  • Your clotting blood tests will be repeated to confirm it has worked.

Evidence & guidelines

Vitamin K, with prothrombin complex concentrate for urgent reversal, is the standard approach to vitamin K antagonist reversal in surgical guidance.

Reference: BSH Anticoagulant Reversal Guidelines 2022; Konakion MM SPC; BCSH Guidelines; 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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