FDA supports limited distribution of antismoking drug Chantix despite carcinogen risk

July 16, 2021, 05:13 PM

Josh Sullivan

Associate Editor

Earlier this month, the FDA alerted the public that Pfizer had voluntarily recalled its stop-smoking drug Chantix after finding elevated levels of cancer-causing nitrosamines. Now, the FDA is permitting certain manufacturers to temporarily distribute the drug that has more than the usual nitrosamine, so long as it remains under the interim acceptable limit.

Pfizer previously halted the distribution of Chantix and pulled four lots of the drug after finding unacceptably high levels of the nitrosamine N-nitroso-varenicline in routine testing. In guidance released Friday, the FDA set an interim allowable limit for that compound in Chantix at 185 ng per milliliter to help ensure adequate supply of the drug in the US.

“Agency scientists evaluated the risk of exposure to N-nitroso-varenicline at interim acceptable intake levels up to 185 ng per day and determined that it presents minimal additional cancer risk when compared to a lifetime of exposure to N-nitroso-varenicline at the 37 ng per day level,” the FDA said in a press release Friday.

The FDA called for patients to continue to take the medication until their doctor prescribes an alternative: “The health benefits of stopping smoking outweigh the cancer risk from the nitrosamine impurity in varenicline,” the release said.

The recall came just a year after the FDA found high levels of NDMA, another common nitrosamine, in some versions of metformin, a popular generic diabetes drug. Viona Pharmaceuticals was the latest generic manufacturer to pull its version off shelves, recalling two lots of its 750 mg extended-release metformin tablets in June.

That marked the fourth version of the drug since November 2020 to be recalled due to reports of NDMA,  which was also implicated in recalls of blood pressure drug valsartan and heartburn med Zantac.

Chantix was first approved by the FDA in 2006 and is used as a prescription in adults who need help quitting smoking. The drugmaker said it is pausing the distribution “out of an abundance of caution.”

The drug is approved in 80 countries, but recall notices have been generated by Canadian and Korean regulators. In Korea, the ministry of food and drug safety has been investigating anti-nicotine therapies that use varenicline as its main compound since June 15, according to the Korea Biomedical Review.

Pfizer will have to test for nitrosamine impurities in all drugs that contain varenicline. The FDA has not yet listed the drug on the recall portion of its website.