The FDA has approved the oral direct thrombin inhibitor dabigatran (da big’ a tran) etexilate (Pradaxa – Boehringer Ingelheim) for prevention of thromboembolic stroke in patients with non-valvular atrial fibrillation. It has been available in Canada (Pradax) since 2008 for prevention of thromboembolism in patients undergoing knee or hip replacement surgery and was recently approved there for use in atrial fibrillation.

The injectable direct thrombin inhibitor desirudin (Iprivask – Canyon), a recombinant analog of hirudin, the leech anticoagulant protein, was approved by the FDA in 2003 for prevention of venous thromboembolism (VTE) after elective hip arthroplasty, but was only marketed recently in the US. It has been available in Europe as Revasc for about 10 years. Two other hirudin analogs are available in the US: lepirudin (Refludan) for treatment of heparin-induced thrombocytopenia (HIT) and bivalirudin (Angiomax) for use in percutaneous coronary intervention (PCI).

The labeling of dabigatran etexilate (Pradaxa – Boehringer Ingelheim), an oral direct thrombin inhibitor, has recently been updated to include new dosing and monitoring recommendations and a warning on the risk of bleeding. Dabigatran etexilate was approved in the US in 2010 for the prevention of thromboembolic stroke in patients with non-valvular atrial fibrillation. It has been shown to be more effective than warfarin (Coumadin, and others) for this indication.

Major orthopedic surgery creates a prothrombotic state by causing tissue injury during the operation and requiring relative immobilization during recovery. Without thromboprophylaxis, 40-60% of patients undergoing major knee or hip surgery develop venographically detectable deep vein thrombosis (DVT) and 1 in 300 undergoing total hip replacement will have a symptomatic pulmonary embolism (PE). Thromboprophylaxis reduces the incidence of venous thromboembolism (VTE), but it also can cause bleeding. New guidelines for prevention of VTE have recently been published.