By Jocelina Joiner Chantix (Credit: FDA) (NEXSTAR) — Pfizer is voluntarily recalling the anti-smoking drug Chantix, a brand of varenicline, due to impurities that exceed approved levels, the Food and Drug Administration has announced. The recall includes two lots of Chantix 0.5 mg tablets, two lots of Chantix 1 mg tablets, and eight lots of a Chantix kit of 0.5mg/1 mg tablets that may have too much nitrosamine, N-nitroso-varenicline, based on the Acceptable Daily Intake (ADI) level established by Pfizer. “N-Nitroso-varenicline belongs to the nitrosamine class of compounds, some of which are classified as probable or possible human carcinogens (substances that could cause cancer), based on laboratory tests such as rodent carcinogenicity studies,” the FDA has said.