Pfizer stamps out another 4 Chantix lots as US shortage drags on

The ongoing shortage of Pfizer's smoking cessation drug Chantix is clearly concerning officials at the FDA, as evidenced by the agency's move to approve imports from Canada and sign off on the first generic. In the meantime, though, Pfizer's recall tally is growing. 

Impurity concerns have prompted Pfizer to pull another four Chantix lots in the U.S., bringing its total recall up to 16 batches. The latest action covers a quartet of 0.5/1-mg tablets and—like earlier Chantix recalls this summer—stems from impurities discovered in the drugs that are above Pfizer’s approved daily limit.

The impurities, called nitrosamines, are an unavoidable part of life, Pfizer has said. They turn up in water, dairy products, vegetables and grilled meats. Ingesting N-nitroso-varenicline long-term “may be associated with a theoretical potential increased cancer risk in humans, but there is no immediate risk to patients taking this medication,” Pfizer said in a recall notice posted on the FDA’s website.

Pfizer shipped the four lots in question to distributors and wholesalers in Puerto Rico and the U.S. between June 2019 and June 2021. Each batch contains two blister packs, one with 0.5 mg tablets and the other containing 1 mg tablets.

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Multiple Chantix doses are currently in shortage as the company conducts product testing, the FDA says. In the meantime, the regulator has summoned Apotex to export its generic Chantix product from Canada to the States.

Meanwhile, the Chantix shortage compelled the FDA to approve Par Pharmaceuticals’ Chantix generic “well ahead” of schedule, the agency said last Wednesday. It remains to be seen when Endo, which owns Par, will launch its drug. But the FDA clearly has smoking cessation supplies on the brain.

The Chantix saga kicked off in June when Pfizer halted shipments worldwide after finding unacceptable nitrosamine levels in certain lots. At the time, a company spokesperson said Pfizer believed the drug’s benefits “outweigh the very low potential risks, if any, posted by nitrosamine exposure from varenicline on top of other common sources over a lifetime.“ In July, Pfizer said it had recalled 12 batches so far in the U.S.

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The issue harkens back to high-profile recalls of valsartan blood pressure meds and metformin diabetes drugs over the past few years, which were linked to the presence of separate but similar nitrosamine impurities. Global “sartan” recalls took place in 2018, while 2020 and 2021 have seen a slate of drugmakers yank their metformin diabetes products at the FDA’s behest.

Meanwhile, another sartan impurity snarl could be on the horizon. Sanofi recently pulled three blood pressure drugs in Korea that contain irbesartan, which has been tied to the discovery of azido impurities in several countries, Korea Biomedical Review first reported.

The U.K. has issued its own azido recall notice for certain batches of Sanofi’s drugs, along with sartan drugs made by Zentiva, Bristol Laboratories, Teva UK and Brown & Burk. Canada has also disclosed recalls on multiple lots of irbesartan, losartan and valsartan drugs on azido impurity fears.