According to a notice published on the US Food and Drug Administration's (FDA) website on 16 September, Pfizer has recalled its anti-smoking drug, Chantix, because of high levels of an ingredient that is allegedly tied to an increased risk of cancer.
The notice shows that Chantix 0.5 mg and 1 mg tablets were recalled over the presence of N-nitroso-varenicline, which is is a nitrosamine, associated with a "theoretical potential increased cancer risk in humans".
Although this nitrosamine is common in water and foods, and everyone may be exposed to it at some level, there is a risk of cancer developing in the case of overexposure.
Pfizer says it recalled the drug as a precautionary measure, but still urges people to stop smoking because this outweighs "the theoretical potential cancer risk from the nitrosamine impurity", according to the company's notice.
In July, Pfizer recalled 12 lots of Chantix due to the presence of N-nitroso-varenicline. Last month, it also recalled four additional lots over the the nitrosamine impurity.