Patients treated with Pfizer’s cholesterol-lowering blockbuster Lipitor were significantly less likely to have a heart attack than those treated with Merck & Co’s now-genericised Zocor.

That is the principal finding from a Pfizer-sponsored observational study, published in Clinical Therapeutics Journal, which was gleaned from the PharMetrics Patient-Centric Database. This looked at the managed care claims of almost 220,000 patients without cardiovascular disease who began statin therapy from January 2003 to September 2005.

The study showed that patients taking Lipitor (atorvastatin) had a 12% lower relative risk of experiencing a cardiovascular event than those on Zocor (simvastatin). The likelihood of a heart attack was 15% lower with the Pfizer drug, while patients taking Lipitor were 12% less likely to need revascularisation compared to patients taking simvastatin. There was no significant difference between the groups in stroke or mini-stroke.

Michael Berelowitz, senior vice president of Pfizer’s global medical division, said that “there has been widespread encouragement by managed care companies and governments” for physicians to prescribe generic statins, assuming that this will result in similar cardiovascular benefits. “This analysis calls into question those assumptions and those policies”, he added.

Patent office rejects claims on Lipitor
Meantime, the US Patent & Trademark Office has rejected Pfizer’s claim to a basic patent covering Lipitor. The company will now file a response making its case for the patent, which is set to expire in March 2010 but the New York-based firm has been looking for an extension to June 2011.

"We continue to believe that the basic patent was properly granted and will be upheld on reexamination," Pfizer general counsel Allen Waxman said. "This initial action, which was not unexpected, does not change that."

If Pfizer fails to win its case, Ranbaxy Laboratories is waiting in the wings. The Indian drugmaker has been granted 180-day exclusive marketing rights for a generic version of Lipitor and will be hoping it can start selling it in 2010 rather than 15 months later.