DOW JONES NEWSWIRES
The U.S. Patent and Trademark Office has sided with Merck & Co. (MRK) in a dispute over its patent for the blockbuster asthma drug Singulair.
The PTO ruled Tuesday that it would end its re-examination of the Singulair patent, which is due to expire in 2012. It launched the re-examination in May at the request of Article One Partners LLC, an online patent-research service that said it uncovered new information raising questions about the validity of the Singulair patent, which was issued in the 1990s.
In early September, the office tentatively rejected key claims in Merck's patent, saying they were "unpatentable" partly because they were anticipated by another patent. The PTO views double-patenting as an unjustified extension of patent exclusivity beyond the term of a patent.
In the latest ruling, the PTO said it withdrew that finding after a doctor provided reasons why the patented procedure was not obvious.
Singulair is Merck's best-selling product, with $3.4 billion in sales for the first nine months of 2009.
Merck's shares rose 1.3%, to $37.75 in after-hours trading. The stock has gained 23% this year.
-By Kathy Shwiff, Dow Jones Newswires; 212-416-2357; Kathy.Shwiff@dowjones.com