Pfizer has announced it has recalled all batches of its popular anti-smoking drug Chantix because of the increased risk of cancer due to high nitrosamine levels, according to a Reuters report. 

When Pfizer halted distribution of the drug in June, a spokesman said the company believed the drug’s benefits outweigh the very low potential risks, if any, posed by exposure to the nitrosamines in the drug.

But a month later, it had to recall more than a dozen lots that were on sale in the U.S. and is now recalling all lots nationwide. 

A Pfizer statement announcing the move said wholesalers “should stop use and distribution and quarantine the product immediately.”

“Nitrosamines are common in water and foods, including cured and grilled meats, dairy products and vegetables. Everyone is exposed to some level of nitrosamines. These impurities may increase the risk of cancer if people are exposed to them above acceptable levels over long periods of time,” he wrote in the statement.

Adding also that “Long-term ingestion of N-nitroso-varenicline may be associated with a theoretical potential increased cancer risk in humans, but there is no immediate risk to patients taking this medication.”

Last Thursday, the company provided details on the batches of the drug Chantix that will be removed from circulation due to the presence of the potentially carcinogenic compound at levels above the acceptable intake limit defined by the FDA. The batches correspond to the 0.5 and 1-milligram tablet formulations.

The affected lots were distributed nationwide in the U.S., Virgin Islands, and Puerto Rico between May 2019 and September 2021.

The U.S. Food and Drug Administration (FDA) approved the questioned drug, also known as varenicline, for adults 18 years and older in 2006. It is generally prescribed for 12 to 24 weeks. 

As reported by the regulatory agency, “there is no immediate risk to patients taking this medication,” but said that “patients currently taking Chantix should consult with their healthcare provider about alternative treatment options.”

Meanwhile, in an update the FDA made Friday, it said patients should “continue taking their current medicine until their pharmacist provides a replacement or their doctor prescribes a different treatment.

“To lessen the impact to patients from a drug shortage due to this ongoing recall, FDA will not object to certain manufacturers distributing varenicline tablets containing N-nitroso-varenicline above FDA’s acceptable intake limit of 37 ng per day but below the interim acceptable intake limit of 185 ng per day until the impurity can be eliminated or reduced to acceptable levels,” the statement said.

According to reports, the Chantix supply disruptions eventually led to a shortage. In response, the FDA in July allowed Apotex to import generics from Canada, which contain N-nitroso-varenicline up to the acceptable intake limit.

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