ANDEXANET ALFA Drug Interactions: What You Need to Know

INTERACTIONS Do not use unfractionated heparin following ANDEXXA administration due to unresponsiveness characterized by non-prolongation of activated clotting times ( 7.1 ). See full prescribing information for details on drug interactions.

7.1 Use with Unfractionated Heparin Unresponsiveness to unfractionated heparin has occurred following ANDEXXA administration, characterized by non-prolongation of activated clotting times and requirement for increased dosing of heparin. Do not use unfractionated heparin following ANDEXXA administration.

7.2 Interference with Anti-FXa Activity Test Current commercial clinical anti-FXa-activity assays are unsuitable for measuring FXa activity following administration of ANDEXXA. Due to the reversible binding of ANDEXXA to the FXa inhibitor, the high sample dilution currently used in commercial clinical assays promotes dissociation of the inhibitor from ANDEXXA, resulting in detection of erroneously elevated anti-FXa activity levels, thereby causing a underestimation of the reversal activity of ANDEXXA.

None. None. ( 4 )

AND PRECAUTIONS

• Arterial and venous thromboembolic events, ischemic events, and cardiac events, including sudden death, have occurred during treatment with ANDEXXA. Resume anticoagulant therapy as soon as medically appropriate following treatment with ANDEXXA . ( 5.1 )
• Unresponsiveness to unfractionated heparin has been reported following ANDEXXA administration. ( 5.2 )
• Re-elevation or incomplete reversal of anticoagulant activity can occur. ( 5.3 )

5.1 Thromboembolic and Ischemic Risks The thromboembolic and ischemic risks were assessed in 419 bleeding -patients in the ANNEXA-4 study who received ANDEXXA and were treated with apixaban or rivaroxaban. There were 45/419 (10.7%) patients who experienced a thrombotic event. The median time to first event was 10 days, and 17 patients experienced the event within three days of treatment. Of the 419 patients who received ANDEXXA, 266 received at least one anticoagulation dose within 30 days after treatment as a prophylactic measure. Of these 266 patients, 14 patients (5.3%) had a thrombotic event after resumption [ see Adverse Reactions (6.1) ]. Monitor patients treated with ANDEXXA for signs and symptoms of arterial and venous thromboembolic events, ischemic events, and cardiac arrest. To reduce thromboembolic risk, resume anticoagulant therapy as soon as medically appropriate following treatment with ANDEXXA [ see Dosage and Administration (2.4) ]. The safety of ANDEXXA has not been evaluated in patients who experienced thromboembolic events or disseminated intravascular coagulation within two weeks prior to the life-threatening bleeding event requiring treatment with ANDEXXA. Safety of ANDEXXA also has not been evaluated in patients who received prothrombin complex concentrates, recombinant factor VIIa, or whole blood products within seven days prior to the bleeding event.

5.2 Unresponsiveness to Unfractionated Heparin Unresponsiveness to unfractionated heparin leading to non-prolongation of activated clotting times and serious thrombotic events has occurred following ANDEXXA administration. [ see Postmarketing Experience (6.2) ]. Do not use ANDEXXA for the reversal of direct FXa inhibitors (apixaban and rivaroxaban) prior to heparinization. If anticoagulation is needed, use an alternative anticoagulant to heparin Use of ANDEXXA as an antidote for heparin has not been established.

5.3 Re-elevation or Incomplete Reversal of Anti-FXa Activity The time course of anti-FXa activity following ANDEXXA administration was consistent among the healthy volunteer studies and the ANNEXA-4 study in bleeding patients [ see Clinical Studies (14) ]. Compared to baseline, there was a rapid and substantial decrease in anti-FXa activity corresponding to the ANDEXXA bolus. This decrease was sustained through the end of the ANDEXXA continuous infusion. The anti-FXa activity returned to the placebo levels approximately two hours after completion of a bolus or continuous infusion. Subsequently, the anti-FXa activity decreased at a rate similar to the clearance of the FXa inhibitors. A total of 114 patients from ANNEXA-4 were anticoagulated with apixaban or rivaroxaban and had elevated baseline levels of anti-FXa (>150 ng/mL for apixaban and >300 ng/mL for rivaroxaban). After administration of ANDEXXA, these patients experienced decreased anti-FXa activity levels, with median reductions of 96% for rivaroxaban and 92% for apixaban .