Pfizer Inc.'s once promising anti-smoking drug Chantix received another blow Wednesday after a nonprofit group's report about serious physical side effects prompted the Federal Aviation Administration to ban the drug's use by pilots and air traffic controllers.
The report, from the Institute for Safe Medication Practices, points out hundreds of serious problems reported since the popular drug was approved in May 2006, including vision and heart problems, dizziness, loss of consciousness, seizures, and abnormal spasms and movements.
"We have immediate safety concerns about the use of varenicline (Chantix) among persons operating aircraft, trains, buses and other vehicles, or in other settings where a lapse in alertness or motor control could lead to massive, serious injury," the researchers said in the report.
FAA spokesman Les Dorr said the Chantix ban is effective immediately and that the agency was notifying unions representing pilots and controllers. He said the FAA is unaware of any aviation accident caused or contributed to by Chantix.
Pfizer, in a statement, reaffirmed its stand on the drug's safety and said the label already contains safety warnings about driving or operating machinery.
"It is important to understand the limitations of spontaneous adverse event reporting," the company said. "Often these reports lack sufficient medical information and/or have confounding factors that prevent a meaningful assessment of causality."
The report specifically cites 173 serious events described as accidental injuries, including 28 road accidents and 77 falls. There were also 68 cases of blurred vision, 86 cases involving seizures and 372 reports of movement disorders. The researchers recommended the Food and Drug Administration undertake an epidemiological study to assess potential risks.
"I've used (the drug) in hundreds of cases and not anyone I've treated or anyone else I know has had a heart or visual problem," said Dr. Marc Siegel, a FOX News medical contributor. "Now, that doesn't mean it can't happen, but it would be a shame to lose the drug because of isolated cases."
Siegel said more studies need to be done on the drug before consumers decide it's not worth taking.
"It's by far the best drug on the market," he added.
The FDA has been under fire for its lack of post-approval tracking of prescription drugs, following several drug safety issues.
Congress last year gave the FDA the authority to order drug label changes and conduct more safety studies after several medicines, including Merck & Co.'s blockbuster Vioxx, were pulled from the market because of their safety risks.
The Institute for Safe Medication Practices' report and Wednesday's move by the FAA come months after the FDA said the connection between Chantix and serious psychiatric problems is "increasingly likely." Pfizer had already added stronger warnings to the drug's label before that opinion was released in February.
New guidelines released this month by the U.S. Public Health Service recommend doctors prescribe the drug to help smokers quit. The new guidelines mention links to depression and suicidal behavior but also say the popular drug is the most effective at helping people get off cigarettes.
Chantix sales totaled $277 million during the first three months of 2008, an increase of 71 percent from a year earlier. For full-year 2007, the drug had sales of $883 million.
Reuters contributed to this report.