New Anticoagulants Safe for Heparin-Compromised Patients

December 15, 2011

December 15, 2011 (San Diego, California) — Heparin-compromised patients can be safely treated with the newer anticoagulants, including dabigatran (Pradaxa, Boehringer Ingelheim), apixaban (Eliquis, Bristol-Myers Squibb/Pfizer), and rivaroxaban (Xarelto, Bayer/Johnson & Johnson), suggest the results from a new laboratory analysis [1]. The new agents did not interact with heparin-induced thrombocytopenia (HIT) antibodies, which suggest they are an anticoagulation option for patients unable to take heparin.

"It's a proof-of-concept study in patients who have existing heparin-induced thrombocytopenia that suggests they can be given these new agents without any of the consequences that we see with heparin," senior investigator Dr Jawed Fareed (Loyola University, Chicago, IL) told heartwire .

The study, presented this week at the American Society of Hematology 2011 Annual Meeting, included blood samples drawn from normal healthy volunteers and HIT sera prepared from clinically symptomatic HIT patients with high concentrations of antiheparin platelet factor 4 antibodies. Rivaroxaban, apixaban, dabigatran, and enoxaparin were dissolved in solution and then each added to separate blood samples drawn from the healthy volunteers. Next, investigators mixed the HIT-positive sera to test for the platelet-aggregation responses of the three new anticoagulants.

Compared with enoxaparin, which resulted in an increase in the antiheparin platelet factor 4 antibodies, apixaban, rivaroxaban, and dabigatran did not increase platelet factor 4 antibodies beyond 15.0 ng/mL. In addition, the researchers noted that none of the new oral agents resulted in platelet aggregation, whereas enoxaparin resulted in a "strong HIT-antibody-mediated response."

"Almost 5% of patients treated with unfractionated heparin have some sort of adverse effects," noted Fareed. "The most serious adverse effect is heparin-induced thrombocytopenia, which has catastrophic outcomes. Of these patients, almost 10% develop thrombosis, HIT syndrome, stroke, and other events. So although it's rare, when [HIT] does occur, the consequences can be very serious."

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