Pfizer is voluntarily recalling all lots of its smoking-cessation product, Chantix (varenicline) (0.5 mg/1 mg tablets), to the patient (consumer/user) level due to the presence of a nitrosamine impurity, N-nitroso-varenicline, a potential carcinogen, found to be at or above the interim acceptable intake limit set by the US Food and Drug Administration’s (FDA).

Pfizer had earlier recalled select lots of Chantix due to the presence of N-nitroso-varenicline. Last month (August 2021), Pfizer recalled four lots of Chantix 0.5-mg tablets/1-mg tablets. In July (July 2021), Pfizer recalled 12 lots of Chantix: two lots of Chantix 0.5-mg tablets, two lots of Chantix 1-mg tablets, and eight lots of a Chantix kit of 0.5-mg/1-mg tablets.

Pfizer said it is now recalling all lots of Chantix (0.5 mg/1 mg tablets) as a precautionary measure as alternative suppliers have been approved in the US.

To date (as reported on September 16, 2021), Pfizer reports that there is no immediate risk to patients taking this medication and that the health benefits of stopping smoking outweigh the theoretical potential cancer risk from the nitrosamine impurity in varenicline. The company noted 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.

The recall of varenicline marks the latest product in the industry to be recalled or investigated for possible nitrosamine impurities.

In 2018, the US Food and Drug Administration and the European Medicines Agency initiated investigations of nitrosamine impurities in certain “sartan”-containing active pharmaceutical ingredients, used in anti-hypertensive and cardiovascular drugs, such as valsartan candesartan, irbesartan, losartan, and olmesartan. They later broadened those investigations into prescription and over-the-counter forms of ranitidine, a H2 (histamine-2) blocker used to decrease the amount of acid created by the stomach, and later metformin extended-release products, used to treat Type II diabetes. As part of their investigations, the regulatory agencies issued guidelines for testing of products to detect nitrosamine impurities, acceptable daily intake levels, and risk evaluation and risk assessment.

Source: Pfizer and US Food and Drug Administration