Hemlibra Drug Interactions

No adequate or well-controlled drug-drug interaction studies have been conducted with HEMLIBRA.
Clinical experience suggests that a drug interaction exists with HEMLIBRA and aPCC (see Precautions and CLINICAL TRIALS under Adverse Reactions).
There is a possibility for hypercoagulability with rFVIIa or FVIII with HEMLIBRA based on preclinical experiments. Emicizumab increases coagulation potential, therefore the coagulation factor dose required to achieve hemostasis may be lower than when used without HEMLIBRA prophylaxis.
Effect of HEMLIBRA on coagulation tests: HEMLIBRA restores the tenase cofactor activity of missing activated factor VIII (FVIIIa). Coagulation laboratory tests based on intrinsic clotting (e.g., aPTT) measure the total clotting time including time needed for activation of FVIII to FVIIIa by thrombin. Such intrinsic pathway-based tests will yield overly shortened clotting times with HEMLIBRA, which does not require activation by thrombin. The overly shortened intrinsic clotting activity assay (see Table 15 under Precautions). However, single-factor assays utilizing chromogenic or immuno-based methods are unaffected by HEMLIBRA and may be used to monitor coagulation parameters during treatment, with specific considerations for FVIII chromogenic activity assays as described as follows.
Chromogenic FVIII activity tests may be manufactured with either human or bovine coagulation proteins. Assays containing human coagulation factors are responsive to HEMLIBRA but may overestimate the clinical hemostatic potential of HEMLIBRA. In contrast, assays containing bovine coagulation factors are insensitive to HEMLIBRA (no activity measured) and can be used to monitor endogenous or infused FVIII activity, or to measure anti-FVIII inhibitors.
HEMLIBRA remains active in the presence of inhibitors against FVIII and so will produce a false-negative result in clotting-based Bethesda assays for functional inhibition of FVIII. Instead, a chromogenic Bethesda assay utilizing a bovine-based FVIII chromogenic test that is insensitive to HEMLIBRA may be used.
Due to the long half-life of HEMLIBRA effects on coagulation assays may persist for up to 6 months after the last dose (see PHARMACOLOGY: PHARMACOKINETICS: ELIMINATION under Actions).