New drug protects against venous blood clots

In the EU blood clots are responsible for killing 544.000 people each year. Rivaroxaban, a new oral given anticoagulant drug from Bayer Healthcare, is significantly more effective than the current standard of care, according to three recent studies. The number of blood cluts in Europe is about 1.5 million per year, more than thirty percent of the patients affected die.

This week´s editions of the two high impact journals, New England Journal of Medicine (NEJM) and The Lancet, publish three clinical phase III studies, demonstrated a new treatment option in total hip and knee replacement surgery. The authors of the studies conclude that the drug rivaroxaban, jointly developed by Bayer Healthcare AG and Johnson & Johnson Pharmaceutical Research & Development L.L.C.,  taken as one tablet daily is significantly more effective in preventing venous thromboembolism than the current standard of care.

 The risk of venous thromboembolism (VTE) -- a blood clot which can be fatal -- is high after the surgeries and can persist after hospital discharge. Consensus guidelines recommend heparin-based thromboprophylaxis (eg, with enoxaparin) in such patients for a minimum of 10 days, and up to 35 days, after surgery, as this prevents the risk of clots.

However such preventive treatment is not used much once the patient leaves hospital, with one prospective registry suggesting less than 50% of patients receive it for at least 28 days. Professor Ajay Kakkar, Barts and the London School of Medicine and Dentistry, and the Thrombosis Research Institute, London, UK, and colleagues did the RECORD2 study (published yesterday in The Lancet) to address this challenge with a new orally active antithrombotic drug. Rivaroxaban is an inhibitor of Factor Xa, which is involved in creating blood clots. Their aim was to compare the use of the oral antithrombotic drug rivaroxaban, used for 31-39 days, with enoxaparin for 10-14 days followed by placebo in patients undergoing THA.
 

In this randomised, controlled trial 2509 patients scheduled for THA were randomly assigned to receive oral rivaroxaban 10mg once daily for 31-39 days (with placebo injection for 10-14 days, 1252 patients) or enoxaparin 40mg once daily subcutaneously for 10-14 days (with placebo tablet for 31-39 days, 1257 patients). The measured endpoint of the trial was a combination of deep-vein thrombosis (DVT), non-fatal pulmonary embolism (NFPE), and all-cause mortality up to days 30-42.

The researchers completed their analysis on 864 patients in the rivaroxaban group and 869 in the enoxaparin group. The primary outcome occurred in 17 patients (2.0%) in the rivaroxaban group and in 81 patients (9.3%) in the enoxaparin group, an absolute risk reduction of 7.3% for the rivaroxaban group. Thus patients in the enoxaparin group were more than four times as likely to suffer DVT, NFPE, or die than those in the rivaroxaban group. Bleeding events during treatment were similar for both groups.
 

The authors conclude: "Extended thromboprophylaxis with rivaroxaban was significantly more effective than short-term enoxaparin plus placebo for the prevention of venous thromboembolism, including symptomatic events, in patients undergoing total hip arthroplasty."

 Two other studies published in New England Journal of Medicine came to similar results. The first study showed that rivaroxaban provided patients undergoing a total hip replacement surgery with a relative risk reduction of 70 percent compared to the standard of care. According to a second study, total knee replacement patient the relative risk reduction decreased by 49 percent.
 
“Today’s publication on rivaroxaban have the potential to change clinical practice in this field”, said Bengt Eriksson, M.D., Ph.D., Department of Orthopaedics, at the Sahlgrenska University Hospital in Sweden and Principal Investigator of the first trial. “The results demonstrate that we now seem to have an effective and safe oral anticoagulant for convenient prophylaxis of venous thromboembolism. This is of great importance since patients undergoing major surgery of the hip and knee are at high risk of developing such potentially life threatening complications and the risk of VTE extends beyond hospitalisation.
 

In an accompanying Comment, Dr John Eikelboom and Professor Jeffrey Weitz, McMaster University, Hamilton, ON, Canada, say: "With superior efficacy, no compromise in safety, and a convenient once daily regimen, rivaroxaban seems an obvious choice for simplified thromboprophylaxis after hip or knee arthroplasty."

Picture:  Tina Carvalho, University of Hawaii at Manoa

26.06.2008

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