Pfizer Pauses Chantix Distribution After Finding Carcinogen


Pfizer Inc. said it’s pausing worldwide distribution of its smoking-cessation drug Chantix after finding elevated levels of nitrosamines, a likely carcinogen, in the pills.

The drug giant is also recalling certain lots of Chantix but didn’t say how many. The distribution halt is out of an abundance of caution, pending further testing, the company said in an email.

The U.S. Food and Drug Administration, as well as other regulatory authorities around the world, have asked pharmaceutical companies to assess their products for nitrosamines after one called N-Nitrosodimethylamine, or NDMA, was found three years ago in blood-pressure pills.

Nitrosamines have since been found in the heartburn drug Zantac and its generic form, ranitidine, which were pulled from the market, and the widely used diabetes drug metformin. The health news website Stat earlier reported that Pfizer paused Chantix distribution.

The benefits of Chantix, known generically as varenicline, “outweigh the very low potential risks, if any, posed by nitrosamine exposure from varenicline on top of other common sources over a lifetime,” Eamonn Nolan, a spokesman for Pfizer, said in an email.

Pfizer rose 0.4% at 3:41 p.m. in New York.

Nitrosamines can also be found in water and in grilled meat. Levels in drugs aren’t currently supposed to exceed a theoretical excess cancer risk of 1 in 100,000.

Chantix sales were $919 million last year, down from $1.1 billion in 2019. One of Pfizer’s main patents on Chantix expired in November and though “generic competition for Chantix has not yet begun, it could commence at any time,” Pfizer said in its quarterly report in May.

Pfizer didn’t say which nitrosamines it found in Chantix nor how the carcinogens got in the pills. Other nitrosamines found in drugs include NMBA and NDEA. Zantac and its generics were pulled from the market because the drugs had the potential to form NDMA over time and in high temperatures. NDMA was found in the blood pressure pills after a solvent used in the drug manufacturing process created a side reaction that formed the carcinogen.

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