Eli Lilly and Daiichi launch Efient in UK

LONDON (Reuters) - Eli Lilly & Co (LLY.N) and Daiichi Sankyo Co Ltd (4568.T) have launched their much-anticipated bloodthinner Efient in its first market, Britain, pricing it at a 31 percent premium to rival Plavix.

Efient, or prasugrel, poses a competitive threat to the $8 billion-a-year (5.4 billion pounds-a-year_ Plavix brand sold by Sanofi-Aventis SA (SASY.PA) and Bristol-Myers Squibb Co (BMY.N).

Both drugs work by stopping platelets -- tiny blood cells vital for the normal clotting process -- from clumping together and forming life-threatening clots in arteries.

The price of a 28-tablet pack of the new drug is 47.56 pounds against 36.35 for Plavix, a spokeswoman said on Wednesday.

Although approved in Europe, Lilly and Daiichi's new medicine is still awaiting clearance in the United States.

Its initial use, alongside aspirin, will be in treating patients with acute coronary syndromes -- an umbrella term covering unstable angina and previous heart attacks -- who undergo a procedure to re-open narrowed or blocked arteries.

In a large study called Triton, Efient was found to be far better than Plavix in preventing blood clots that can cause heart attacks and strokes, but it was associated with a higher degree of serious bleeding.

Overall, for every 1,000 patients treated with Efient instead of Plavix, there were six more major bleeding events but 23 fewer heart attacks, Lilly and Daiichi said.

(Reporting by Ben Hirschler; Editing by Rupert Winchester)