Fact check: Pfizer recalled smoking cessation drug Chantix for high levels of potential carcinogen

·5 min read

The claim: Pfizer's Chantix was recalled for causing cancer

Pfizer may be best known for its COVID-19 vaccine, but the pharmaceutical giant also made waves recently over a lesser-known drug social media users are claiming is unsafe.

"FDA approval 2006, recalled 2021 for causing cancer," reads the meme shared to Facebook on Sept. 28.

The meme says Pfizer's smoking-cessation medication Chantix causes cancer and asserts this adverse effect "took 15 years to find out."

The post connects this to vaccine safety with a caption that reads "Safe and effective..." invoking the description regularly used by government and health officials noting the vaccines' proven safety record in studies.

Similar posts elsewhere on Facebook and Instagram echo the meme's claim, citing the recall as evidence against the safety of the COVID-19 vaccines and grounds to question the credibility of the Food and Drug Administration.

The various posts have accumulated hundreds of interactions in the last several weeks, according to CrowdTangle, a social media insights tool.

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While it's true Pfizer voluntarily recalled Chantix – FDA approved in 2006 – in September, it wasn't because of any confirmed reports of cancer. But it did contain a chemical impurity involving nitrosamine, which is capable of potentially causing cancer.

USA TODAY reached out to the Facebook users for comment.

Nitrosamines are potential carcinogens

Nitrosamines are nitrogen-bearing chemicals found widespread in nature, said Dr. J. Taylor Hays, director of the Mayo Clinic's Nicotine Dependence Center.

"Nitrosamines are found in many foods ... Tobacco-specific nitrosamines are formed as part of the fermentation process when tobacco is cured and they are highly carcinogenic," he wrote in an email.

The FDA said in drugs, like Chantix, nitrosamines are considered an unintentional chemical impurity. They arise due to how a drug is manufactured, its underlying chemical structure, its packaging and storage conditions or contamination from an external source.

Nitrosamines impurities have affected not only Chantix but other drugs over the years, Lisa Kroon, co-director of the University of California San Franciso Health Fontana Tobacco Treatment Center, told USA TODAY.

"Other drugs have recently been recalled too, due to unacceptable.... levels, such as ranitidine (completely pulled from the market), some blood pressure medicines (losartan, valsartan), and a diabetes medicine metformin," she said in an email.

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Nitrosamines are considered potentially carcinogenic – capable of causing cancer – at a level above 37 nanograms per day and pose a minimal cancer risk at levels up to 185 nanograms, according to the FDA.

"Nitrosamine impurities may increase the risk of cancer if people are exposed to them above acceptable levels," FDA spokesperson Jeremy Kahn told USA TODAY in an email.

Some recalled Chantix lots were found to contain nitrosamine levels as high as 150 to 470 nanograms per pill, according to laboratory testing conducted by the agency.

However, Kahn said patients who are currently on Chantix are not at any immediate risk for cancer. And health care professionals are still recommending the medication for its efficacy in helping patients quit smoking, Hays said.

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Dr. Nancy Rigotti, director of Massachusetts General Hospital's Tobacco Research and Treatment Center, agreed, telling USA TODAY, "Patients who smoke should not be afraid to use this medication."

Hays mentioned the usual treatment course for Chantix isn't long-term, typically running from 12 weeks to up to 24 weeks or a little more for people who are at higher risk of relapsing.

Pfizer spokesperson Steven Danehy told USA TODAY the recall only affects current batches of Chantix, and in a Sept. 16 press statement, the pharmaceutical company said the nationwide recall of the drug was a "precautionary measure."

No confirmed reports of cancer associated with Chantix

The active ingredient in Chantix is a chemical called varenicline, which works by attaching to nicotine receptors in the brain and preventing any other molecule, like nicotine, from binding, according to MedlinePlus.

Varenicline is also offered by Apotex, a Canadian pharmaceutical company, which is temporarily supplying the medication to the U.S. to alleviate the shortage brought on by the recall.

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However, there have been no reports varenicline causes cancer, Rigotti said.

Hays agreed: "There's no evidence that anyone who ever took Chantix developed cancer as a result of their exposure to the drug... This is compared with smoking that is associated with about 30% of all cancer deaths in the US."

Our rating: False

Based on our research, we rate FALSE the claim Pfizer's Chantix was recalled for causing cancer. Smoking cessation drug Chantix was recalled for higher than acceptable levels of a potential carcinogen called nitrosamine, a chemical impurity tied to recalls of other drugs as well. Health experts say there is no evidence Chantix caused cancer.

Our fact-check sources:

Contributing: Kelly Tyko

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This article originally appeared on USA TODAY: Fact check: Pfizer recalled Chantix for high levels of nitrosamine

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