Two leading drugmakers are collaborating over an experimental treatment intended to prevent strokes in people with dangerously irregular heartbeats.
Merck is to pay Portola Pharmaceuticals an initial $50 million (£31m) to license betrixaban, which prevents blood clots by blocking the Factor Xa clotting protein.
If upcoming trials involving patients suffering from atrial fibrillation are successful, the licensing fee may rise to a possible $470 million.
This is because future sales may reflect the fact that the condition affects seven million people in the US and Europe, and that the drug has two other benefits.
First, it is suitable for patients with severe kidney disease because it is mostly excreted through other means, and secondly, it may produce fewer drug interactions than other anticlotting treatments.
These include warfarin, which often involves patients needing follow-up blood tests to get the dosage right and prevent bleeding or other side effects.
Copyright Press Association 2009