Study Sees Pfizer Smoking Drug Risk

May 22, 2008— -- Hundreds of patients taking Pfizer Inc's anti-smoking drug Chantix have reported serious accidents, vision problems and heart trouble, researchers said on Wednesday, sending shares of the world's largest drugmaker to their lowest level since 1997.

U.S. aviation regulators responded quickly to the research,saying they would prohibit use of Chantix by private andcommercial pilots, while consumer advocates called for strongerwarnings on the drug's label.

Chantix, also known as varenicline, has already been linkedto depression and suicide, among other problems.

Researchers at the nonprofit Institute for Safe MedicationPractices, and Wake Forest University, said they found hundredsof reported problems since the drug's 2006 approval thatincluded blurred vision, dizziness, confusion and loss ofconsciousness.

"These data provide a strong signal that the risks ofvarenicline treatment have been underestimated and show that awide spectrum of serious injuries are being reported in largenumbers," the researchers said.

The data does not definitively prove that Chantix is atfault but does show a strong signal, the researchers cautioned,adding that the U.S. Food and Drug Administration and Pfizershould take further steps, including conducting more studies.

Pfizer officials defended Chantix, one of the strugglingdrugmaker's newest medicines, saying the side effects arealready mentioned on the drug's label.

"When you've got the nicotine withdrawal along withChantix, it's just very difficult to tell what is causing it,"said Gretchen Dieck, Pfizer's senior vice president for safetyand risk management.

Chantix works by targeting brain receptors affected bynicotine, tobacco's addictive ingredient. The drug blocks someof the effects of nicotine while also providing a nicotine-likebuzz to help curb withdrawal.

Shares of the drugmaker fell 1.2 percent to $19.76 inafter-hours trading Wednesday following release of the study,having closed on the New York Stock Exchange down 4 cents at$20.01.