What was found in Varenicline?

In 2021, the FDA recalled certain batches of varenicline, a smoking cessation drug, due to detection of a nitrosamine impurity, N-nitroso-varenicline, above the FDA’s acceptable intake limit. FDA stated that this chemical may be associated with an increased cancer risk in humans, but according to the FDA “… there is no immediate risk to patients taking this medication.”   That view was based on animal testing of nitrosamines conducted in the 1970s.

FDA indicated that  “… there are no data to directly evaluate the carcinogenic potential of N-nitroso-varenicline, [therefore] information available on closely related nitrosamine compounds was used to calculate lifetime exposure limits …”

What is being done to mitigate any potential risk of exposure to N-nitroso-varenicline?

The acceptable intake limit of this nitrosamine was changed from 37 ng per day to up to an interim concentration of 185 ng per day until the impurity can be eliminated or reduced to acceptable levels. The change in acceptable intake limit was determined by agency scientists to present minimal risk.

Manufacturers of the brand name, Chantix, have recalled 16 lots of varenicline as the investigation continues. The FDA has urged patients taking this medication to continue to take their current medication until they are given a replacement by a pharmacist, or their doctor prescribes a different treatment. The FDA indicated that “[t]he health benefits of stopping smoking outweigh the cancer risk from the nitrosamine impurity in varenicline.”

Our firm understands that personal injury litigation has begun.  As is customary, we recommend that those firms who have nitrosamine impurities in their products conduct a thorough health risk assessment so they can fully characterize the possible health risks to users, as well as the strength of their defense if they are drawn into the courtroom.  As we have shown in the past, when Agencies identify acceptable daily intakes or tolerance levels, they often imbed many conservative assumptions that can produce risk estimates that are not representative of the risks potentially posed to the vast majority of users.  Normally, this is not fully recognized by the manufacturer of the drug or consumer product.

Paustenbach and Associates scientists have extensive experience in conducting consumer product safety assessments and evaluating the potential health risks of possible impurities from consumer products. Specifically, some of our staff have 40 years of experience at assessing the presence of trace quantities of impurities in pharmaceuticals and characterizing the potential for chronic health hazards. Often, we are successful in working with the Agencies to identify product specific guidelines and have offered testimony in court on such matters. Our scientists have published more than 300 papers on relevant topics. Please contact us for more information regarding Paustenbach and Associates’ capabilities.