NEW YORK The U.S. Patent and Trademark Office plans to uphold the patent protection of a blockbuster blood-thinning drug, thus reducing the chances of the launch of a generic before the patent expires, according to published reports.

Published reports cited a notice that the office issued on Friday saying that it would uphold claims to the drug Plavix (clopidogrel) by Bristol-Myers Squibb Co. and Sanofi-Aventis. Patent protection for the drug expires in 2011, while the patent covering the drug’s use in children expires the year after.

Plavix had U.S. sales of $4.9 billion in 2008, according to IMS Health.