FONDAPARINUX AND APTT

Fondaparinux Sodium (Arixtra) Injection Linked to Elevated aPTT With Bleeding Events

In October 2008, the FDA revised the safety labeling for fondaparinux sodium injection (Arixtra; GlaxoSmithKline) to warn of the potential for elevated activated partial thromboplastin time (aPTT) temporally associated with bleeding events. These events have been reported after administration of fondaparinux sodium injection, with or without concomitant administration of other anticoagulants.

Postmarketing experience has included reports of isolated occurrences of aPTT elevations after administration of fondaparinux sodium injection, as well as reports of isolated occurrences of thrombocytopenia with thrombosis resembling heparin-induced thrombocytopenia, and several cases of epidural or spinal hematoma.

The anticoagulant effects of fondaparinux sodium injection may last even longer in patients with renal impairment. As with other anticoagulants, fondaparinux sodium injection should be used with extreme caution in conditions with elevated risk for hemorrhage, such as congenital or acquired bleeding disorders; active ulcerative and angiodysplastic gastrointestinal tract disease; hemorrhagic stroke; during the postoperative period of brain, spinal, or ophthalmologic surgery; or in patients also receiving platelet inhibitors.

Prothrombin time and aPTT are relatively insensitive measures of the activity of fondaparinux. If unexpected changes in coagulation parameters or major bleeding occur during therapy, fondaparinux should be discontinued. Any degree of thrombocytopenia should be monitored closely, and fondaparinux should be discontinued if platelet count decreases to less than 100,000/mm³.

Latex-sensitive individuals may have allergic reactions to the dry natural latex rubber in the needle guard of the prefilled syringe of fondaparinux sodium.

Fondaparinux sodium injection, a synthetic and specific inhibitor of activated Factor X, is indicated for deep vein thrombosis prophylaxis after hip fracture, hip or knee replacement surgery, or abdominal surgery; and for treatment of deep vein thrombosis and pulmonary embolism.