Stop-smoking drug risks outweighed by benefits

By Graham Lanktree

The smoking cessation drug varenicline tartrate was touted as a magic bullet for nicotine addiction when it hit the market in Canada a year ago last month. But between its launch and late November 2007, Health Canada received 107 reports of adverse reactions linked to the drug, nearly half of which were psychiatric. Last month this led to a change in the drug's labelling and a 'Dear doctor' advisory.

Though most adverse reactions were mild, there were 14 cases of aggression, depression and suicidal ideation. Several patients experienced suicidal thoughts while taking the medication, four of whom had no previous history of mental illness.

Of the 220,000 Canadians who have been prescribed varenicline, not one report of suicide has been linked to it here (34 suicides have been linked to the drug in the US). Because of these reports many of your patients may prefer to keep puffing rather than take this drug.

RISKY BUSINESS?
"The first thing you should tell them is that some of these adverse events may occur," says Dr Peter Selby, the clinical director of the addictions program at the Centre for Addiction and Mental Health in Toronto. "But patients must be reminded these will be short-term discomforts versus the longterm gain of being smoke-free." A reasonable risk he says, considering one in two smokers will die of a smoking related illness.

Compared to the total number of patients on varenicline, those who've experienced strong side effects make up about 0.048% of the total number, says Dr Selby. "That being said, you still have to be cautious with new medications and keep an eye out for common side effects. If any of your patients have strong mood changes they should discontinue treatment and be switched to another drug right away."

Dr Andrew Pipe, a cardiologist at the University of Ottawa Heart Institute who was named to the Order of Canada for his work on smoking cessation, suggests switching these patients to the stop-smoking drug bupropion because of its antidepressant qualities. "The drug may make them feel nauseous, but that can be taken care of by reducing their dose to 150mg once-a-day from the usual 120mg twice-a-day," he says.

Dr Pipe consulted for Pfizer during the clinical trials of varenicline and remains a strong proponent. He says 30% of smokers already have some psychological imbalances and that quitting smoking will often unmask those symptoms.

CHANGING BEHAVIOUR
Dr Pipe recommends sitting with each patient and identifying with him or her tangible benefits that smoking cessation will have on their health. They should also be made aware of varenicline's stimulation of nicotine receptors, which gives them the feeling as though they've just smoked a cigarette. "Some patients might think 'that was easy' after the first few weeks and then quit the treatment," he says. "They need to be told why they're feeling the way they are and reminded to stay on the 12-week course."

Counselling patients about picking a quit date and simple behavioural strategies and techniques will help too, says Dr Selby. "Counselling should include strategies for making their home environment smoke-free, manage their eating and weight gain, and how to engage with their friends who are still smokers."

Physicians should also check in regularly with patients, says Dr Pipe. "If you're dealing with a patient who has been depressed in the past and their attempts to quit have failed, then they might not be able to take varenicline. We should be careful about who we give this treatment to."