Pfizer recalls all Chantix lots nationwide over concerns of cancer-causing impurity

Pfizer's headache with its popular smoking cessation drug Chantix is escalating. After the drugmaker halted global distribution this summer and then recalled more than a dozen lots in the U.S., the company is now recalling all lots nationwide.

Pfizer on Thursday said it's expanding its Chantix recall to the consumer level to include all batches of the drug at the 0.5-mg and 1-mg doses. The company is recalling the drug as a "precautionary measure" because the medicine contains unacceptable levels of N-nitroso-varenicline, a type of nitrosamine, and because there are now "alternative suppliers" of the medicine for the U.S.

Nitrosamines are found in water and foods including grilled and cured meats, Pfizer says. While everyone is exposed to them during their lifetime, nitrosamines can cause cancer at high levels of exposure over time.

RELATED: Pfizer yanks 12 Chantix lots on carcinogen concerns after pausing global shipments last month

Pfizer's Chantix mess started this summer, when the company said in June it was halting global shipments after testing found the impurity. At the time, a spokesperson said the company believed the drug's benefits "outweigh the very low potential risks, if any, posed by nitrosamine exposure" from the drug.

Then, a month later, Pfizer recalled 12 lots in the U.S. The drugmaker further expanded its recall in August.

RELATED: Pfizer halts global Chantix distribution after testing flags impurities

The Chantix supply disruptions eventually sparked a shortage. Responding to those supply concerns, the FDA in July allowed Apotex to import generics from Canada. Last month, the agency approved a U.S. generic from Endo's Par Pharmaceutical.

First approved in 2006, Pfizer's smoking cessation drug pulled in $919 million last year.