Pfizer won a crucial battle in its quest to widen the market for its Chantix smoking cessation pill late Wednesday when a federal advisory panel recommended that a serious warning about neuropsychiatric side effects should be removed from the product labeling.
The recommendation followed a two-year effort by the drug maker to remove a so-called Black Box warning — the most serious type of health alert — that indicated Chantix could cause patients to experience such side effects as suicidal thoughts and hostility. An earlier attempt in 2014 failed when an FDA panel voted to recommend that the warning should remain intact.
The side effects have plagued the drug ever since it was approved a decade ago and endured horrendous publicity about violent or suicidal behavior. As a result, Pfizer spent hundreds of millions of dollars to settle numerous lawsuits and sales for the pill — once pegged to become a blockbuster — have plateaued, sliding from $846 million in 2008 to $671 million in 2015.
In making its recommendation, a US Food and Drug Administration advisory panel reviewed the results of a study that was released earlier this year and found that Chantix does not appear to increase the risk of suicidal behavior. An FDA medical review team had cast doubt on the study due to problems with collecting and analyzing side effect data as well as ties some investigators had to Pfizer.
Among patients already diagnosed with a psychiatric disorder, 6.5 percent of those on Chantix had a neuropsychiatric side effect, compared to 4.9 percent on placebo. Of those not diagnosed with a psychiatric disorder, 1.3 percent of those on Chantix experienced such a side effect, compared to 2.4 percent on a placebo. The study also examined patients given Zyban, which is sold by GlaxoSmithKline.
The study involved 8,144 adult participants between the ages of 18 and 75 who, on average, smoked more than 10 cigarettes a day. And 82 percent had previously made at least one attempt to quit smoking. Of these, about half — or 4,116 participants — had a history of a previous or current stable psychiatric condition. About half of these people were taking a psychotropic medicine.
“We believe this is an important step toward updating the Chantix labeling to more accurately reflect its neuropsychiatric safety profile and help patients and prescribers make informed decisions about treatment options,” said Dr. Freda Lewis-Hall, Pfizer’s chief medical officer and an executive vice president, in a statement.
Whether the FDA follows the recommendation of the advisory committee is uncertain. The agency is not obligated to do so and the vote was not straightforward — 10 committee members agreed the Black Box warning should be removed, while four voted to modify the labeling, and five voted the warning should remain intact.
One consumer advocate expressed surprise that a majority of committee members voted to remove the warning, given questions about the study. Sammy Almashat of Public Citizen, the consumer advocacy group, noted the study included composite outcomes of both serious and milder symptoms, including irritability and agitation, which normally occur in people who are trying to quit smoking.
“A Black Box warning has been rescinded very few times in the past,” he said. “This could set an ominous precedent. If the FDA rescinds, a company can now go to the agency with a substandard post-marketing trial, point to Chantix and demand the same outcome. We’re worried that if the FDA follows through with the recommendation, that this will become a new standard for removing a black box.”