The US Patent and Trademark Office (USPTO) will confirm the validity of Pfizer's US patent covering the crystalline form of atorvastatin calcium used as the active ingredient in the cholesterol-lowering medicine Lipitor.

According to a Pfizer release, the patent office undertook a review of the patent in response to a legal challenge to the crystalline form patent for atorvastatin calcium which expires in 2017. In its response to the patent office, Pfizer argued that the unique crystalline form of atorvastatin calcium used in Lipitor had not been described in the prior art before the submission of the company's application to the patent office.

The patent office decision regarding the crystalline form of atorvastatin calcium used in Lipitor is separate from the ongoing patent litigation with Ranbaxy in the US, which involves the basic and enantiomer patents that provide market exclusivity for Lipitor through March 2010 and June 2011, respectively.

"We are pleased that the patent office agreed with our arguments in this case which further confirms the strong patent position surrounding Lipitor," said Jeffrey Kindler, vice chairman and general counsel of Pfizer. "We see this decision as affirming that important advances in medical innovation like Lipitor deserve strong patent protection under our laws."

The release further stated that since its introduction in the US in 1997, Lipitor has become the world's most prescribed cholesterol-lowering therapy. More than 18 million people in the US have been prescribed Lipitor for lowering their cholesterol, and it is approved in more than 70 countries. Clinical research has also shown that Lipitor provides unique benefits that go beyond LDL cholesterol reduction, such as reducing cardiovascular events and halting the progression of atherosclerosis, or hardening of the arteries. Most recently, the US Food and Drug Administration approved a new indication for Lipitor for the millions of people who suffer from diabetes.