Pfizer says no safety concerns in Celebrex studies

Three long-term studies conducted by Pfizer seeking additional uses for its popular arthritis drug Celebrex have turned up no cardiovascular safety concerns, according to the company

Pfizer released the information after Merck pulled its rival arthritis drug Vioxx from the market when a study found long-term use of the medicine doubled the risk of heart attack and stroke. The stunning Vioxx news raised concern about the entire class of drugs known as COX-2 inhibitors to which Celebrex also belongs.

"In light of recent events we really want to reassure doctors who we work with and patients who take our product that we don't really have a cardiovascular concern," said Dr Mitch Gandelman, Pfizer's vice president for worldwide medical, oncology and pain information.

Pfizer, the world's biggest drugmaker, stands to be the big winner from the Merck debacle if most Vioxx patients end up switching over to Celebrex. Vioxx had annual sales in excess of US$2.5 billion a year.

The Merck study that led to the Vioxx withdrawal was designed to see if the drug could prevent recurrence of colon polyps, which can become cancerous. Increased heart risk began to appear after 18 months of use and was double in patients taking Vioxx for three years.

Pfizer said two of its ongoing Celebrex studies were for the same indication, while a third was testing the drug for use against Alzheimer's disease.

The three studies, which are testing Celebrex at various doses versus a placebo, involve more than 6,000 patients, Pfizer said.

In one of the colon polyp trials, more than 900 patients had been taking Celebrex for three years with no evidence of increased cardiovascular risks, Gandelman said. In the other, 325 patients had reached the three-year mark without turning up significant safety concerns.

The studies are expected to follow those patients for five years.

"Each COX-2 inhibitor has a distinct chemical structure and we would not expect them to have the same side-effect profile," Joe Feczko, Pfizer's president of worldwide development, said in a statement issued by the New York drugmaker.