Pfizer voluntarily recalled all lots of Chantix (varenicline), a popular smoking-cessation drug, on September 16, according to a notice on the FDA’s website. The recall, which includes all 0.5-mg and 1-mg tablets, was initiated “due to the presence of a nitrosamine, N-nitroso-varenicline, at or above the FDA interim acceptable intake limit.”
Another type of nitrosamine, N-nitrosodimethylamine, drove the recalls of ranitidine, metformin, and losartan in recent years.
A nicotine-free prescription pill, Chantix is intended to help patients quit smoking by reducing the urge to smoke. It is intended for use for 12 to 24 weeks. Chantix received FDA approval in 2006.
Pfizer first issued a recall of four lots of the drug at the warehouse level in June, when the company announced that it would stop global production. Pfizer then expanded the recall in early July to 12 lots. At the time, the FDA encouraged the company to expand the recall to the consumer level, a step Pfizer took later in July. In August, the company further expanded the recall to 16 lots before recalling all product in September.
The recall notice said that long-term use of the drug may be associated with a “theoretical potential increased cancer risk in humans,” although patients face no immediate risk. Although no data exist that enable direct calculation of the cancer risk posed by N-nitroso-varenicline, the FDA used data on similar nitrosamines to calculate the recommended limits for lifetime exposure and establish the usual intake limit of 37 ng per day.
Nitrosamines occur commonly in water and in foods, particularly cured and grilled meats, but they are also found in dairy products and vegetables. Although small amounts of nitrosamines are unavoidable, animal studies indicate that larger amounts stimulate tumor growth.
The benefit of smoking cessation outweighs the possible cancer risk posed by the contaminant, according to the FDA. Consequently, patients should “continue taking their current medicine until their pharmacist provides a replacement or their doctor prescribes a different treatment.”
The FDA made replacement a little easier for pharmacists by exercising regulatory flexibility. To lessen the impact of a drug shortage on patients while Pfizer works to eliminate the impurity or bring it below the usual intake limit, the agency has permitted Apotex to distribute APO-Varenicline tablets with N-nitroso-varenicline levels up to the FDA’s interim acceptable intake limit of 185 ng per day. Apo-Varenicline has Health Canada approval. FDA scientists determined that the interim level “presents minimal additional cancer risk.”
Another product that could help patients stop smoking is bupropion, which is often prescribed as an antidepressant but also has FDA approval for smoking cessation. Nicotine-replacement therapy also helps some people quit.
The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.
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