The US Food and Drug Administration has awarded priority review to a thrombin inhibitor developed by Schering-Plough currently in Phase II testing and tipped as a future blockbuster for the group.

The orally-active drug, called SCH 530348, is being tested for secondary prevention of cardiovascular morbidity and mortality in at-risk patients, including acute coronary syndromes and peripheral arterial disease. The FDA said the indication represents an unmet medical need at present.

SCH 530348 could emerge as a competitor to existing products such as AstraZeneca’s direct thrombin inhibitor Exanta (ximelegatran), an orally active direct thrombin inhibitor which was first launched in Europe last year for a different indication, the short-term prevention of venous thromboembolism, although this product has been delayed in the USA.

Schering-Plough said the drug is being investigated to determine whether it has the potential to provide clinical benefit through inhibition of this thrombin mediated platelet activation without the liability of increased bleeding, a tendency associated with other antithrombotic drugs. It refers to SCH 530348 as the first in ‘a potentially new class of drugs called thrombin receptor antagonists’.

Boehringer Ingelheim is developing a direct thrombin inhibitor called Rendix (dabigatran etexilate) in Phase III trials to prevent strokes in patients with atrial fibrillation, as well as in the prevention and treatment of deep vein thrombosis after orthopaedic surgery.

It could also become a rival to oral Factor Xa inhibitors, such as Sanofi-Aventis’ Arixtra (fondaparinux) – sold for the treatment and prevention of deep vein thrombosis and pulmonary embolism - and Bayer’s BAY 59-7939, due to start Phase III testing before the end of the year.