A federal appeals court on Monday declined to review a previous ruling that granted a split decision to

Pfizer

(PFE) - Get Report

on two patents for its cholesterol drug Lipitor.

The U.S. Appeals Court for the Federal Circuit in Washington, D.C., won't rehear an

Aug. 2 ruling by a three-judge panel from the same court. In December 2005, a trial court had upheld both of Pfizer's patents.

The appeals court's decision upholds Pfizer's most important U.S. Lipitor patent, which is due to expire in March 2010, but it also supports the challenge by India's

Ranbaxy Laboratories

to another patent that expires in June 2011. The 2010 patent is the basic patent for Lipitor, the world's best-selling prescription drug. The 2011 patent is for a calcium salt of Lipitor.

The latest ruling had little affect on investors. Shares of Pfizer were off 7 cents to $27.61 recently.

Pfizer said it will return to the U.S. Patent and Trademark Office to seek to correct what it calls a "technical defect" in the 2011 patent. In August, the company said the adverse ruling on the 2011 patent was based on this technicality. Pfizer said Ranbaxy could appeal the latest appeals court action to the U.S. Supreme Court.

Last week, Pfizer

reaffirmed its goal of achieving about $13 billion in Lipitor sales for this year. For the third quarter, Lipitor produced worldwide sales of $3.32 billion, up 15% from the same period last year.

For the first nine months, Lipitor contributed $9.55 billion in sales, up 8%. Lipitor accounts for more than one-quarter of Pfizer's total revenue.