FDA skepticism greets Pfizer's latest bid to escape the Chantix black box

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FDA scientists are looking askance at Pfizer’s latest attempt to lift a black-box warning from its stop-smoking drug Chantix.

Ahead of an advisory panel meeting Wednesday, agency staffers questioned a study the drug giant conducted to assess the real-world risk of the neuropsychiatric side effects flagged in that label warning.

The FDA reviewers disputed the study’s results, citing the way some side effects were characterized and pointing to inconsistencies in data-collection methods. These details could have biased the study results, the reviewers said in a briefing document.

The 8,000-patient study compared Chantix to GlaxoSmithKline’s Zyban (bupropion) and to nicotine patch therapy. The participants included patients with and without a history of mental health problems. The conclusion: Chantix did not significantly increase the risk of neuropsychiatric side effects.

Pfizer attempted in 2014 to use a range of data to remove Chantix’s black-box warning. But the FDA chose to not only keep the black box, which highlights warnings about suicide and suicidal thoughts, but also to add new cautionary advice about Chantix's interactions with alcohol.

Some Chantix patients had reported unusual or aggressive behavior while drinking, the agency said at the time, and a few experienced seizures.

Earlier this year, European regulators did pull their severe warning on Chantix, which is sold there under the Champix brand name. That moved was based on a study in which scientists tracked 150,000 smokers in England over 6 months. They concluded that people who took Chantix were not at higher risk of depression or self-harm. 

When the results were released in March, Pfizer CMO Freda Lewis-Hall said the new data added to “the large body of clinical evidence characterizing the neuropsychiatric safety and efficacy” of Chantix and highlighted the drug “as an important treatment option for people who want to quit smoking.”

“We believe the available scientific information doesn’t support a boxed warning,” Lewis-Hall said at the time.

Now, Pfizer has another chance to make that case--and an FDA panel of experts has another opportunity to sift the latest data and weigh in.

Questions about effects arose soon after the company launched Chantix in 2006. Reports began to surface that the drug could cause mental health problems in some users. In 2009, the agency slapped the drug with a black-box warning--its most serious safety designation. A couple years later, the FDA updated the label with further precautions, and the alcohol warning was added last year.

Along the way, Pfizer has made Chantix one of the most-advertised prescription drug brands. The company spent $103 million on ads in 2014. The company’s Chantix TV commercial, “Claudine,” is one in a series of currently running ads that feature former smokers and their experiences trying to quit.

The safety questions have cut into sales; originally tabbed as a blockbuster, the drug delivered sales of $671 million last year.

Special Report: The top 10 most-advertised prescription drug brands - Chantix

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