The news comes after Pfizer Inc. halted the distribution of its anti-smoking drug Chantix and was forced to recall several charges after finding elevated levels of nitrosamines in the pills.
The nitrosamine impurity, called N-nitroso-varenicline, may be associated with a potential increased cancer risk in humans, but the FDA says there is no immediate risks to patients who take the medication, reports Reuters. The regulator also stated that the health benefits of quitting smoking outweighed the cancer risk from the impurities in varenicline.
As a result of the findings, the US drug regulator will temporarily allow manufacturers to distribute varenicline-containing impurities above its intake limit of 37 nanograms per day, but below an interim limit of 185 ng per day, until the impurity can be eliminated or reduced to acceptable levels, according to Reuters. In order to maintain the US varenicline supply, Canadian drugmaker Apotex will also be allowed to distribute its Apo-Varenicline tablets in the US until further notice.