Published: 1 March 2018

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Idarucizumab — A Second Dose May Be Needed

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Prescriber Update 39(1): 2
March 2018

Prescribers are alerted to the possibility that some patients may need a second dose of idarucizumab (Praxbind) to reverse the effects of dabigatran (Pradaxa).

Idarucizumab is a specific reversal agent for the direct-acting thrombin inhibitor dabigatran. Idarucizumab is a humanised monoclonal antibody fragment (Fab) that binds to dabigatran more strongly than thrombin (around 300 fold more potent). As a result of this strong binding affinity, idarucizumab rapidly neutralises the anticoagulant effect of dabigatran¹.

Idarucizumab is indicated in patients treated with dabigatran when rapid reversal of dabigatran’s anticoagulant effect is required for emergency surgery/urgent procedures or in life-threatening or uncontrolled bleeding¹.

Idarucizumab comes in 50 mL vials containing 2.5 g per vial (50 mg/mL). The recommended dose of idarucizumab is 5 g (2 x 2.5 g/50 mL vials) administered intravenously either as two consecutive infusions over 5–10 minutes each or as a bolus injection.

Post-marketing experience with dabigatran has shown that a second dose of idarucizumab is sometimes required². Administration of a second 5 g dose of idarucizumab may be considered in patients with prolonged clotting times who develop a recurrence of bleeding or who require a second emergency surgery/urgent procedure.

The timing of the second dose depends on the timing of the recurrence of bleeding and the measurement of the elevated coagulation tests. Please refer to the data sheet for further information¹.

References

1. Boehringer Ingelheim (NZ) Limited. 2017. Praxbind Data Sheet 17 July 2017. URL: www.medsafe.govt.nz/profs/Datasheet/p/praxbindinj.pdf (accessed 17 January 2018).
2. Pollack CVJ, Reilly PA, van Ryn J, et al. 2017. Idarucizumab for Dabigatran Reversal — Full Cohort Analysis. New England Journal of Medicine 377: 431-41.