Vitamin K1 re-established for over-anticoagulation
Vitamin K1 re-established for over-anticoagulation
Oral dosage as good as parenteral
Decades ago, researchers provided a strong case for oral vitamin K1 as an alternative to parenteral therapy for correcting excessive anticoagulation in patients receiving warfarin. Yet the oral therapy is virtually unused today, a new study finds.1
The study looks at patients with international normalized ratios (INR) greater than five and without evidence of major bleeding complications.
Of those, 81 received 2.5 mg of oral vitamin K1 and were instructed to withhold their warfarin until their next visit, and 58 held one dose of warfarin and were seen within 24 hours. The remainder held two doses and were seen between 24 to 48 hours. The goal was to lower the INR to between two and five, at which time warfarin was restarted provided any minor bleeding had stopped.
Excluding patients whose initial INR was greater than 10, 96% of patients had an INR of less than five at follow-up. Seventy-two percent of patients who were re-evaluated within 24 hours had reached the target INR, as did 74% of those seen at 24 to 48 hours. Seventeen percent of patients were "overcorrected," with an INR of less than 2.0. No patient developed thromboembolic or hemorrhagic complications, and no patient had warfarin resistance when anticoagulation therapy was resumed.
Study confirmed treatment is safe
The investigators confirmed that oral vitamin K1 is safe and effective for the routine management of patients with warfarin-induced over-anticoagulation. Be aware that as a fat-soluble vitamin, oral vitamin K1 therapy may be inappropriate for patients with fat malabsorption. And some clinicians consider withholding warfarin in favor to administering vitamin K1 in certain situations, such as when dropping the INR into the normal range, even briefly, would pose an unacceptable risk of thromboembolic complications.
Reference
1. Weibert RT, et al. Correction of excessive anticoagulation with low-dose oral vitamin K1. Ann Intern Med 1997; 125:959-962.
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