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Pfizer turns up defense of smoking cessation drug
  Thu Jun 5, 2008 3:29pm EDT
By Bill Berkrot
NEW YORK (Reuters) - Pfizer Inc on Thursday turned up public relations efforts to defend its drug to help smokers quit after a recent report said there have been hundreds of problems with patients taking Chantix since its 2006 approval.
The world's largest drug maker, which is counting on robust Chantix sales to spur growth and help right its foundering share price, defended the product's safety and effectiveness at a panel discussion for reporters with its medical and safety officials.
Joseph Feczko, Pfizer's chief medical officer, said more than 90 percent of the reported adverse events that created the wave of fresh negative publicity last month was old news that Pfizer had already shared with the U.S. Food and Drug Administration.
Still, FDA officials said last week they were taking a closer look at Chantix following the report released by the nonprofit Institute for Safe Medication Practices (ISMP) and Wake Forest University that included incidents of heart problems, blurred vision, dizziness and loss of consciousness.
Chantix, known chemically as varenicline, had previously been liked to reports of depression, suicidal thoughts, strange dreams and other psychological effects. The ISMP report added to a cloud already hanging over the drug.
Gretchen Dieck, Pfizer's head of safety and risk management, attempted to throw some cold water on the ISMP report, saying it had not been peer reviewed or published in a peer-reviewed journal.
She added that you can't tell by numbers of reported incidents whether they represent a true safety signal. Dieck noted that jumps of reports of problems tend to coincide with increased media reporting of adverse effects.
Compared to carefully controlled clinical trials, the company insisted it was very difficult to determine from anecdotal reports whether a problem is caused by the drug, symptoms of nicotine withdrawal or unrelated health issues.
"Nicotine is a very powerful addiction," said Ponni Subbiah, vice president of Pfizer Medical and head of the Chantix team. "We don't know what is causing what, but the withdrawal phenomenon is important to bear in mind and it is something we're going to have to do more research on."
Clinical trial data often fails to mirror the effect of a medicine once it is in wide use.
David Gonzales, co-director of Oregon Health & Science University's Smoking Cessation Center who led pivotal studies of Chantix, noted that "patients in the trials are not terribly reflective of the population of smokers."
Gonazales, who attended the discussion but was not part of the Pfizer panel, said smokers with a host of mental and physical health problems are excluded from placebo controlled trials due to fears of exacerbating their conditions but exist in large numbers in the general population.
Pfizer said it does not believe the Chantix label needs stronger safety warnings. Analysts have said sales would be hard hit if the FDA adds a stronger black box warning.
"We strongly believe that the current label really reflects what is the current evidence with regards to the safety and efficacy profile of the product," Dieck said.
The company, which halted direct-to-consumer Chantix advertising in January, resumed an ad campaign this month that does not mention the drug by name but urges smokers trying to quit to seek information from their doctors. It has not yet decided when it will bring back ads for Chantix.
The drug, which had sales of $277 million in the first quarter, has already been used by 6 million people worldwide, 5 million of them in the United States, the company said.
Chantix works by blocking the nicotine receptors in the brain.
"I think the safety profile of this drug is particularly good," said Gonzales, who has conducted smoking cessation studies for 20 years on a variety of drugs, including many that were never approved for sale.
He said no more than 5 percent of people who attempt to quit smoking without drugs or nicotine replacements are successful. In trials, Chantix helped more than 40 percent of patients quit smoking.
"Any of the (smoking cessation) drugs out there are substantially better than doing it on your own," he said.
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