Pfizer is recalling three more lots of its smoking cessation drug Chantix (varenicline) after having issued a voluntary recall of the drug earlier this month due to carcinogen concerns, bringing the total number of affected lots to 12.
The Chantix recall is over the finding of the purported carcinogen N-nitroso-varenicline (a nitrosamine) in levels above Pfizer’s pre-set acceptable daily intake (ADI), according to the company in an announcement posted on the US Food and Drug Administration (FDA)’s website.
The company had initially implemented a global distribution hold in late June when the nitrosamine was first detected in Chantix tablets during routine testing. As a result, there are currently shortages of the drug in the US.
Despite this, Pfizer said there is no immediate danger to patients taking the medication. Any increased cancer risk linked to the drug is associated with long-term exposure to it. As such, the company said the health benefits of curbing smoking outweigh the theoretical potential cancer risk from the nitrosamine impurity in the drug. Pfizer said the benefit/risk profile of Chantix remains positive.
People who smoke cigarettes are 15 to 30 times more likely to get lung cancer than people who do not smoke, and they are also associated with many other cancers, said the FDA.
Pfizer said the Chantix recall includes two 0.5 mg tablet lots; two 1 mg lots; and eight lots of a Chantix kit that includes 0.5 mg and 1 mg doses. The products were shipped throughout the US and Puerto Rico between June 2019 and June 2021.
Pfizer wants people to note that nitrosamines are common in water and foods, such as vegetables and dairy products, as well as grilled and cured meats. “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,” said the company in the statement.
Chantix is a treatment intended for short-term use to help individuals stop smoking. To date, Pfizer said it hasn’t gotten any reports of adverse events related to the recall.
The FDA has advised that patients taking recalled varenicline should continue taking their current medication until their pharmacist can offer a replacement or their doctor prescribes an alternate medication to treat the same condition.
To address the shortages resulting from the Chantix recall, the FDA has given some manufacturers the go-ahead to temporarily distribute varenicline tablets with N-nitroso-varenicline levels above the FDA’s acceptable intake limit of 37 ng per day, but below an interim limit of 185 ng a day, “until the impurity can be eliminated or reduced to acceptable levels.” This temporary measure includes allowing Apotex — which distributes varenicline in Canada — to send its generic Apo-Varenicline tablets to the US.
Pfizer’s branded Chantix generated about $919 million last year and lost US patent protections in November. It is not known whether generics companies have received approvals to launch in the US.
Chantix has a safety profile that has been established over 15 years of marketing authorization and through a robust clinical program, according to the FDA. The agency said patients currently taking Chantix should consult with their doctor to find out whether they received an affected lot and to talk about alternative treatment options if necessary.
Drug recalls due to nitrosamine impurities has been an ongoing issue in the last couple of years. This includes ongoing recalls of metformin and pulling of the heartburn medication Zantac (ranitidine) in 2019 (and continuing into 2020) due to above-limit levels of nitrosamine N-nitrosodimethylamine (NDMA) found in the drugs.
Blood pressure medications of the “sartan” family, such as losartan and valsartan, have also been facing a similar fate over azido impurities found in the products.
Both metformin and losartan recalls have continued into 2021. Apotex, Actavis, Amneal, Lupin and Marksans are among the companies that were called on by the FDA in May to remove their extended-release metformin formulations off the shelves, while Sanofi-Aventis Canada Inc. recalled 12 lots of irbesartan, losartan and valsartan in June.
Recently, Johnson & Johnson pulled some of its spray sunscreens under the Aveeno and Neutrogena brands off the shelves over the presence of higher than acceptable amounts of the carcinogen benzene.