In August 2017, Pollack et al published the full cohort analysis of 503 patients from the REVERSE-AD trial. The robust findings validated the initial results from the interim analysis of 90 patients. In those patients receiving dabigatran with prolonged dTT and uncontrollable bleeding or need for an urgent procedure, idarucizumab reversed the anticoagulant activity of dabigatran in more than 98% of patients. The 30-day and 90-day mortality data were similar between the groups and were concluded to be due to the initial event or comorbid conditions and less likely as a result of idarucizumab effects.23

Following the interim analysis findings from the REVERSE-AD trial, idarucizumab received accelerated approval on October 16, 2015, for patients requiring emergent surgery/urgent procedures or life-threatening/uncontrolled bleeding. The recommended dose is 5 grams, given as two separate vials each containing 2.5 grams/50 milliliters.18 The wholesale acquisition cost of two vials of 2.5 grams of idarucizumab is about $3500.24 Even though the data have high impact, there are limitations to the study. First, most hospitals do not routinely use dTT or ECT levels, complicating the ability to measure the effects of idarucizumab on dabigatran reversal. The reason for their use in this study was based on their high correlation with unbound dabigatran levels.21 However, hospitals do routinely order aPTT as a coagulation parameter. Given that the study showed maximum reversal within the first few minutes and normalization of aPTT after idarucizumab administration, aPTT may be a potential coagulation parameter for monitoring idarucizumab. Second, there was no control group in the study; however, the authors acknowledge this limitation and state that it would be unethical to randomly assign patients to a placebo group given there are no approved alternatives to idarucizumab. Third, the REVERSE-AD trial did not evaluate any other specific indications for idarucizumab other than uncontrollable bleeding or need for urgent procedure. These data will need to be explored in future studies.


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Potential alternative reversal agents

Three other potential methods have been evaluated as reversal agents for dabigatran. Khadzhynov et al conducted an open label, single center, phase 1 study to evaluate the elimination of dabigatran with renal replacement therapy in patients with end-stage renal disease. Their study findings showed that intermittent hemodialysis decreased plasma dabigatran concentrations by 48.8% to 59.3%.25 In 2011, Erenberg et al conducted a randomized, double-blind, placebo-controlled study evaluating the reversal effects of prothrombin complex concentrate (PCC) on rivaroxaban and dabigatran. They concluded that PCC quickly and completely reversed the effects of rivaroxaban but had no effect on dabigatran.26

In contrast, in 2012, Pragst et al conducted an open-label, placebo-controlled study evaluating the reversal effects of PCC among rabbits treated with dabigatran. They concluded that PCC decreased blood loss and increased hemostasis in a variety of dabigatran doses. Importantly, the doses used were similar to those used in clinical practice.27 Lastly, Lange et al showed that dabigatran can be removed via activated charcoal; 75% to 80% of circulating dabigatran was reduced after 1 hour and levels were undetectable after 2 hours. However, the maximum binding capacity for activated charcoal is 30 mg of drug, far less than the current recommended dose of dabigatran.28 Even though these studies may have promising potential, future large human randomized studies are warranted to determine their efficacy in reversing the effects of dabigatran as well as their efficacy when compared with idarucizumab.

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Given the recent updates on oral anticoagulation in the literature and findings from multiple large clinical trials showing the efficacy of DOACs, these drugs will become the leaders in antithrombotic therapy. Therefore, advances in new reversal agents will be a key piece to the puzzle for managing patients treated with DOACs to prevent major bleeding events. The promising data from the interim and full cohort analysis of the REVERSE-AD trial has put idarucizumab in the spotlight as the first approved DOAC reversal agent. However, future studies on idarucizumab are warranted to establish its potential indications in different patient populations.

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Zachary Lavender, PA-C, MHS, and Peter S. Sandor, RRT, MHS, PA-C, DFAAPA, are critical care physician assistants based in Hartford, Conn., and faculty members at Quinnipiac University in Hamden, Conn.

References

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