Pfizer will look to re-submit corrections to its US Lipitor patent after the US Patent and Trademark Office rebuffed an initial attempt. Reissuing a corrected patent, as Pfizer is seeking to do, would help the company retain US marketing exclusivity on atorvastatin until 2011.

Last year the patent term on the anti-cholesterol med was shortened by a year, from June 2011 to March 2010, when a federal appeals court deemed one Lipitor patent invalid, reversing a lower court's decision. Generic manufacturer Ranbaxy had challenged the patent.

At the time, Pfizer said that the decision “turned on a technical defect” and that it planned to apply to the PTO to correct it.

As Pfizer spokesman Bryant Haskins told The Wall Street Journal , “An initial rejection is not uncommon in reissue application proceedings.” He went on to say that once the company receives a letter from the PTO explaining its decision, it will review and respond appropriately to address any issues raised.