OTTAWA — After concern was raised last spring in the U.S. regarding an anti-smoking drug, Health Canada is set to update its advisory label for the same drug.

Health Canada is reminding Canadians who are taking, or considering taking, the smoking-cessation aid Champix of important safety information for this product. Health Canada is also informing Canadians that it is in the process of further strengthening the labelling for the drug with respect to the risk of serious psychiatric adverse effects.

While Champix (the brand name for varenicline tartrate) can be an effective tool for quitting smoking when used as part of a support program, there have been reports in some patients of unusual feelings of agitation, depressed mood, hostility, changes in behaviour, or impulsive or disturbing thoughts such as thoughts of self-harm or harm to others. However, it is unclear at this time whether Champix is the cause of these psychiatric symptoms.

Health Canada suggests people using Champix to tell their doctor if they have experienced depression or other mental health problems before taking Champix, as these symptoms may worsen while taking the drug. Patients are also reminded to avoid driving a car or operating hazardous machinery until they are reasonably certain that Champix does not affect them adversely.

Health Canada is currently working with Pfizer, the manufacturer of Champix, to update the prescribing information to reflect current safety information. This update is the result of continuing reports, in Canada and internationally, of serious psychiatric symptoms associated with the use of Champix, and is intended to increase awareness of this risk.

The drug is marketed as Chantix in the U.S. and in May 2008 the Federal Aviation Administration banned the use of Chantix for pilots and air traffic controllers. The Federal Motor Carrier Safety Administration responded shortly after advising medical examiners "not qualify anyone currently using this medication for commercial motor vehicle licences."