When it is necessary to thin the blood with an oral anticoagulant, warfarin, a vitamin K antagonist, is the reference treatment. Dabigatran (Pradaxa°), an anticoagulant from a different pharmacological class (thrombin inhibitor), is an option only when warfarin is not recommended. All anticoagulants expose the patient to the risk of severe, sometimes fatal haemorrhages.

In the case of severe haemorrhage or of emergency surgical intervention, it may be necessary to halt the anticoagulant. Vitamin K, the antidote to warfarin and other vitamin K antagonists, enables the restoration of coagulation in patients treated with these drugs.

Idarucizumab, a monoclonal antibody presented as a specific antidote to dabigatran, has been authorised in the EU.

Its efficacy has not been established to date: we only have the interim analysis of a non-comparative trial on 123 patients, the results of which are difficult to interpret. In patients who experienced haemorrhage, it was halted in most cases after an average period of around 10 hours, but other measures were also taken to stop it. Many of the patients given idarucizumab prior to surgery were operated on apparently without excessive bleeding, but the absence of a comparison means that it is not possible to prove the role of the drug. We do not know whether the normalisation of certain laboratory markers observed with idarucizumab translates into a reduced risk of haemorrhage.

Until we have reliable, robust evidence, it is better not to rely on idarucizumab but generally to opt for warfarin, whose antidote has a proven efficacy.

©Prescrire 1 November 2016

"Idarucizumab (Praxbind°). Don't rely too heavily on this dabigatran antidote" Prescrire Int 2016; 25 (176): 260-263. (Pdf, subscribers only).