Treatment Reversal Strategies
ÎInterruption of VKAs may be sufficient in patients who need an elective invasive procedure or in asymptomatic patients with an elevated INR value and a low risk for bleeding.
Notes: ▶ It takes approximately 2.5 days for an INR between 6.0 and 10.0 to decline to < 4.0. ▶ Because acenocoumarol has a much shorter half-life (0.5 h) than warfarin (36-42 h), the time required for an effective decline will be less and is probably no more than 1 day for most patients.
▶ Conversely, the longer half-life of phenprocoumon (5.5 days) will probably result in a much slower decline.
▶ Finally, the half-life of fluindione (70 h) is similar to that of warfarin, and thus a similar decline should be expected.
ÎLow doses of phytonadione (vitamin K1 ) can be administered orally in
combination with warfarin interruption in patients not requiring urgent reversal. Approximately 1.4 days are required for an INR between 6 and 10 to decline to < 4.0.
ÎIntravenously administered phytonadione works more rapidly than either oral or subcutaneous vitamin K1
.
Notes: ▶ Reduction of the INR begins within 2 h, and a correction to within the normal range is generally achieved within 24 h if hepatic function is normal and if a sufficiently large dose is given. At 24 h, 5 mg of oral and 1 mg of intravenous (IV) vitamin K produce similar effects on the INR.
▶ To minimize the risk of anaphylactoid reactions (3 per 10,000 doses), vitamin K1
ÎFresh frozen plasma remains the most widely used coagulation factor replacement product for urgent reversal of coumarin anticoagulation.
Notes: ▶ The short half-life of infused coagulation factor concentrates requires that phytonadione also be given.
▶ Nonactivated prothrombin complex concentrates (PCC) are probably more effective than plasma in correcting INR.
ÎIn patients with life-threatening bleeding, recombinant activated factor VII has been used to control bleeding.
be mixed in a minimum of 50 mL of intravenous fluid and administered, using an infusion pump, over a minimum of 20 min.
should
