Bayer and Johnson & Johnson are celebrating after regulators in the USA finally gave a thumbs-up to their oral anticoagulant Xarelto.

The US Food and Drug Administration has given the green light to Xarelto (rivaroxaban) for the prevention of deep vein thrombosis which may lead to a pulmonary embolism in people undergoing knee or hip replacement surgery. The drug is approved for use at a 10mg dose, with one tablet taken once-daily for 35 days following hip replacement and for 12 days following knee replacement surgery.

The approval is based on Phase III data which showed superior efficacy of Xarelto, both in head-to-head comparison with Sanofi's Lovenox (enoxaparin) and when comparing extended-duration (ie 5 weeks) rivaroxaban with short-duration (2 weeks) of enoxaparin followed by placebo. In these trials, the drugs demonstrated similar safety profiles including low rates of major bleeding.

Bayer noted that Xarelto is the only new oral anticoagulant with US approval in venous thromboembolism (VTE) prophylaxis for patients undergoing knee or hip replacement surgery (Lovenox is injected).

Rivaroxaban, a Factor Xa inhibitor, has been available for the above indication in Europe since 2008 but the road to approval across the Atlantic has been more complicated. In May 2009, the FDA issued a complete response letter and the information the agency required was only submitted by J&J in January this year.

The knee and hip surgery approval is clearly good news but more lucrative indications are being targeted. Regulatory filings in Europe, the USA and Japan have been submitted seeking approval of Xarelto for the prevention of stroke in patients with atrial fibrillation (AF) and decisions in the first two territories are expected before the end of the year.

Bayer has repeatedly forecast Xarelto sales of over 2 billion euros, most of which would be derived from the AF indication. However, it will have some ground to make up on Boehringer Ingelheim's Pradaxa (dabigatran) which was approved by the FDA in October last year and has got off to a strong start. European approval for the later drug is expected imminently.