Summary
Several new anticoagulants have entered the clinical arena or are under clinical development.
These drugs include indirect (fondaparinux) and direct oral factor Xa inhibitors (rivaroxaban,
apixaban, edoxaban, betrixaban), and the direct thrombin inhibitor dabigatran. Especially
the oral direct FXa and FIIa inhibitors overcome many of the shortcomings of heparins
and vitamin K antagonists (VKAs). They are administered orally at a fixed dose; regular
monitoring is not necessary; interaction with other drugs or nutrition occur less
than with VKAs and they are at least as effective as VKAs for most indications tested.
They are associated with about 50 % less intracranial bleeding than VKAs. Nevertheless,
they are still associated with bleeding complications. Bleeding can occur spontaneously
or as a result of trauma or urgent surgery. In such situations rapid reversal of the
anticoagulant effect is highly desirable. For unfractionated heparin protamine, and
for VKAs prothrombin complex concentrates are available as specific antidotes. Under
clinical development are: for the direct and indirect FXa inhibitors a modified recombinant
FXa (andexanet alpha), which lacks enzymatic activity; and for dabigatran a Fab fragment
of a monoclonal antibody (idarucizumab). In addition a small molecule (aripazine)
has entered phase I clinical trials, which seems to inhibit nearly all anticoagulants
but VKAs and argatroban. This review summarises the current options and strategies
in development to antagonise anticoagulants with a focus on the status of the development
of antidotes for the oral direct FXa and FIIa inhibitors.
Keywords
New anticoagulants - antidotes - apixaban - dabigatran - rivaroxaban