Monitor for development of thrombotic microangiopathy (TMA) & thromboembolism when administering activated prothrombin complex concentrate (aPCC) in patients receiving Hemlibra prophylaxis. Immediately discontinue aPCC & interrupt therapy if TMA & thrombotic events occur. Discontinue treatment w/ bypassing agents the day before the start of Hemlibra therapy. May increase coagulation potential. Initial dose should not exceed 50 U/kg in patients indicated w/ aPCC during Hemlibra therapy. May affect results of activated partial thromboplastin time (aPTT), Bethesda assays for FVIII inhibitor titers, 1-stage, aPTT-based, single factor assays (eg, FVIII activity), aPTT-based activated protein C resistance (APC-R), & activated clotting time (ACT). Women of childbearing potential should use effective contraception during & for at least 6 mth after cessation of treatment. Pregnancy & lactation.