Pfizer's Lipitor patent term secure

The best selling drug in the world received a boost yesterday that will allow Pfizer to maintain its patent expiration date, currently set for June 2011.

The patent for the popular cholesterol drug, Lipitor, had a technical defect, which the U.S. Patent & Trademark Office allowed the company to correct. That's good news for Pfizer, because a loophole in the wording could have allowed a generic maker to make its way in, and cut into Pfizer's $13 billion-a-year sales, and getting in on the good fortune of Lipitor is on the minds of many generics manufacturers hoping to capture some of the market share. 

At issue was a very specific structure that determines the active ingredient in Lipitor, which makes the drug active, as well as stable, according to Pfizer spokesperson, Chris Loder. The patient for "enantiomer 995" had a claim in it with an improper cross reference to another patent claim. 

Initially, Pfizer sued Ranbaxy to prevent it from challenging two Lipitor patents and won, but a Court of Appeals ruling in December 2006 found the '995 patent had a technical defect, as one claim within it contained an improper cross reference to another claim in the patent. The following month, to resolve the issue, Pfizer applied with the patent office to correct the defect by removing the cross reference and have the patent reissued, which the Court agreed to allow Pfizer to do once it pays a small fee.

The original case started when Ranbaxy Laboratories went to the FDA to challenge Pfizer's patent in hopes of selling a generic version of Lipitor. As it stands today, Ranbaxy will be the first company to sell a generic version of Lipitor starting in November 2011. It will have a six-month period to do so unhindered by other generic competition.

- read the story at CNN Money
- here's the Associated Press version