F8 and hemophilia: As far as the interference of these drugs with one stage and chromogenic assays it is well known that emicizumab concentration can be measured by means of a modified one-stage FVIII clotting assay and that a bovine chromogenic assay, which is insensitive to emicizumab can be used to measure FVIII levels in plasma of patients with hemophilia without inhibitors [67].