Formulary

9.6.6 Vitamin K

First Line
Second Line
Specialist
Hospital Only

The oral coumarin anticoagulants, warfarin and phenindione, interfere with Vitamin K metabolism in hepatic cells and their effects can be reversed by vitamin K. If anticoagulation with warfarin is to be continued but rapid reversal of over- anticoagulation is needed a small oral dose of 0.5 to 1mg of vitamin K is generally sufficient. Larger doses lead to prolonged resistance to warfarin.

Intravenous injections of vitamin K should be given with caution as anaphylaxis may occur.

Menadiol sodium phosphate
  • Tablets 10mg (£132.56 = 20mg daily)

Indications

  • Prevention of vitamin K deficiency in malabsorption syndromes
Phytomenadione (Vitamin K1)
  • Solution for injection 10mg/1ml (£1.05 = 1ml ampoule)
  • Solution for injection 2mg/0.2ml (£2.10 = 0.2ml ampoule)

Notes

  1. May be given by a single intramuscular injection at birth - see local hospital policy
  2. May be used to reverse over-anticoagulation