From the Research
After a Coumadin (warfarin) overdose, vitamin K administration should typically be stopped once the INR reaches 1.8-2.0, or within the patient's target therapeutic range. The decision to stop vitamin K should be individualized based on the patient's specific condition and indication for anticoagulation, as well as their risk of bleeding and thrombotic events 1. Some key points to consider when discontinuing vitamin K administration include:
- The patient's target therapeutic INR range, which is typically 2.0-3.0 for most patients on warfarin, but may be higher (2.5-3.5) for those with mechanical heart valves 1
- The risk of bleeding, which increases dramatically when the INR exceeds 4.0-6.0, although the absolute risk of bleeding remains fairly low, <5.5 per 1000 per day 1
- The risk of thrombotic events, which may occur if vitamin K is continued beyond the target INR, leading to warfarin resistance for several days 2
- The importance of close INR monitoring after stopping vitamin K, as the INR may rebound once the vitamin K effect wears off 3
It is also important to note that the use of vitamin K in patients with warfarin over-anticoagulation lowers excessively elevated INR faster than withholding warfarin alone, but it has not been clearly demonstrated that vitamin K treatment does, in fact, lower the risk of major hemorrhage 1. Additionally, the route of vitamin K administration may also be a consideration, with oral administration being preferred due to the risk of anaphylactoid reactions with intravenous administration and cutaneous reactions with subcutaneous administration 1. Overall, the goal is to balance the risk of bleeding and thrombotic events, and to individualize treatment based on the patient's specific needs and circumstances.