The new anti-clotting drug produced by Merck & Co. and Portola Pharmaceuticals Inc., called betrixaban, has shown greater effectiveness than warfarin. A recent study has observed that the patients of atrial fibrillations suffered lesser bleeding when given a light dose of betrixaban than those who were given warfarin. Warfarin is essentially a 50 year old blood thinner.

However, as per the findings of the research team, the bleeding rates do not reduce much in comparison with the rate in warfarin dosage, if the dosage of betrixaban is kept higher.

Atrial fibrillations is a situation wherein blood clots get formed in heart of a patient and they further lead to a stroke.

The results of the study led by Michael Ezekowitz were released at the 59th Annual Scientific Session of the American College of Cardiology in Atlanta.

The study examined 508 patients. Betrixaban has so far benefitted around 2.2 million Americans suffering from atrial fibrillation.

"Betrixaban appears to be safe and well tolerated in a real-life diverse atrial fibrillation population", said Ezekowitz.

Betrixaban was licensed from Portola of South San Francisco, in California. The flourishing of betrixaban would bring an amount of $470 million to Portola in imbursement from Merck and the royalties.