Thromb Haemost 2009; 101(01): 68-76
DOI: 10.1160/TH08-07-0460
Blood Coagulation, Fibrinolysis and Cellular Haemostasis
Schattauer GmbH

A randomized evaluation of betrixaban, an oral factor Xa inhibitor, for prevention of thromboembolic events after total knee replacement (EXPERT)

Alexander G. G. Turpie
1   McMaster University, Hamilton, Ontario, Canada
Kenneth A. Bauer
2   Beth Israel Deaconess Medical Center, Boston, Massachussetts, USA
Bruce L. Davidson
3   Weill Cornell Medical College, Doha, Qatar
William D. Fisher
4   McGill University Health Centre, Montreal, Quebec, Canada
Michael Gent
1   McMaster University, Hamilton, Ontario, Canada
Michael H. Huo
5   University of Texas Southwestern Medical Center, Dallas, Texas, USA
Uma Sinha
6   Portola Pharmaceuticals, Inc., South San Francisco, California, USA
Daniel D. Gretler
6   Portola Pharmaceuticals, Inc., South San Francisco, California, USA
for the EXPERT Study Group › Author Affiliations
Further Information

Publication History

Received: 01 August 2008

Accepted after major revision: 22 October 2008

Publication Date:
23 November 2017 (online)


Betrixaban is an oral direct inhibitor of factor Xa (FXa) being developed for the prevention of venous thromboembolism (VTE). Its antithrombotic effects had not been previously tested in patients. This exploratory clinical trial in the US and Canada randomized 215 patients undergoing elective total knee replacement (TKR) in a 2:2:1 ratio to receive post-operative betrixaban 15 mg or 40 mg p.o. bid or enoxaparin 30 mg s.c. q12h, respectively, for 10–14 days. The betrixaban dosage was blinded, but enoxaparin was not. Primary efficacy outcome was the incidence of VTE, consisting of deep-vein thrombosis (DVT) on mandatory unilateral (operated leg) venography, symptomatic proximal DVT, or pulmonary embolism (PE) through Day 10–14. Safety outcomes included major and clinically significant non-major bleeds through 48 h after treatment. All efficacy and bleeding outcomes were adjudicated by a blinded independent central adjudication committee. Of 214 treated patients, 175 (82%) were evaluable for primary efficacy. VTE incidence was 14/70 (20%; 95% CI: 11, 31) for betrixaban 15 mg, 10/65 (15%; 95% CI: 8, 27) for betrixaban 40 mg, and 4/40 (10%; 95% CI: 3, 24) for enoxaparin. No bleeds were reported for betrixaban 15 mg, 2 (2.4%) clinically significant non-major bleeds with betrixaban 40 mg, and one (2.3%) major and two (4.6%) clinically significant non-major bleeds with enoxaparin. A dose- and concentration-dependent effect of betrixaban on inhibition of thrombin generation and anti-Xa levels was observed. Betrixaban demonstrated antithrombotic activity and appeared well tolerated in knee replacement patients at the doses studied.

* Study participants are listed in the Appendix.

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