Drug Interactions between Heparin Sodium and oritavancin

CONTRAINDICATED: Use of oritavancin may interfere with the therapeutic monitoring of heparin therapy. Oritavancin can bind to and prevent the action of the phospholipid reagents that activate coagulation in commonly used laboratory coagulation tests. Administration of oritavancin has been shown to artificially prolong the activated partial thromboplastin time (aPTT) for up to 120 hours and activated clotting time (ACT) for up to 24 hours following a single 1200 mg dose. Oritavancin does not affect the coagulation system in vivo, however.

MANAGEMENT: Use of intravenous unfractionated heparin is contraindicated for 120 hours (5 days) after oritavancin administration. For patients who require aPTT monitoring within 120 hours of oritavancin dosing, a non-phospholipid dependent coagulation test such as a Factor Xa (chromogenic) assay or an alternative anticoagulant not requiring aPTT monitoring may be considered.