Effective Reversal of Warfarin-lnduced Excessive Anticoagulation with Low Dose Mtamin K₁

Summary

Reversal of the anticoagulant effect of warfarin in patients with no active haemorrhage can be achieved by administration of intravenous vitamin K₁. Currently recommended doses of intravenous vitamin K₁, for this purpose often result in subsequent difficulties in anticoagulation. We observed the response to low dose intravenous vitamin K₁ in patients requiring reversal of anticoagulant therapy. Ten consecutive patients received L mg and 2l further patients received 0.5 mg of intravenous vitamin K₁. In 50% of the patients who received 1 mg of vitamin K₁ the INR (International Normalised Ratio) fell below 2 at 24 h whereas in patients who received 0.5 mg the INR fell below 5.5 in all subjects after 24 h and in none did it fall below 2.0. No patient had any thrombotic or haemorrhagic complications and no difficulty was encountered in re-establishing anticoagulant control after 24 h. We recommend 0.5 mg of vitamin K₁ as an effective and convenient method of predictable and fine control of oral anticoagulant therapy.

• References

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