Question: What is the explanation for a “rebound” in INR that may be seen following the successful treatment of warfarin overdose with vitamin K1?
Answer: The cited article notes “Treatment with early doses of vitamin K1 will result in initial INR improvement, which can be falsely reassuring. If the patient’s INR is not closely monitored, there is a risk of a rebound increase in the INR. The reason for this rebound is that warfarin has a much longer half-life (estimates of 44 hours in overdose) than vitamin K1 (elimination half life of 1.7 hours).” (Berling I. et al. Warfarin poisoning with delayed rebound toxicity. 2017 J Emerg Med 52(2): 194-196)
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