The present invention relates to the identification and use of antigen-binding regions, antibodies, antigen-binding antibody fragments and antibody mimetics, neutralizing the anti-coagulant effect of an anticoagulant in vitro and/or in vivo. Antibodies and functional fragments of the invention and antibody mimetics can be used to specifically reverse the pharmacological effect of an anticoagulant e.g. a FXa inhibitor for therapeutic (antidote) and/or diagnostic purposes. The invention also provides nucleic acid sequences encoding foregoing molecules, vectors containing the same, pharmaceutical compositions and kits with instructions for use.
