Thom Jancewicz and Gayle Nakamoto. (Courtesy Gayle Nakamoto)

A drug commonly used to help people quit smoking is the focus of more than 800 complaints from Canadian users, many of them reporting mood swings, depression or suicidal thoughts.

Of the 818 complaints about Champix (varenicline tartrate) Health Canada has received complaints on its adverse reaction database, 520 involved psychiatric problems.

The medication acts on sites in the brain affected by nicotine. It helps ease withdrawal symptoms and blocks the effects of nicotine if a user resumes smoking.

'What will I do now? I have no father.'— Ellaina Jancewicz

The drug has been sold in Canada since April 2007. From January to November 2008, nearly 1.1 million Champix prescriptions were dispensed from Canadian retail pharmacies, according to IMS Health Canada, which tracks the pharmaceutical industry.

Each prescription comes with a long list of potential side-effects, from depression to aggression to suicidal thoughts.

One of the people to report a complaint to Health Canada, Erin Kerr of Hamilton said she was on Champix for a couple of months to try to quit smoking when she noticed dramatic changes in her personality — she had become intolerant, argumentative, emotional, and then one day, suicidal.

"As I'm driving along the [Hamilton] mountain brow, I just thought that driving off … would have been the easy way out at that point and would solve all my problems," Kerr said.

In the U.S., the drug is called Chantix. Last year, the U.S. Food and Drug Administration used a video to warn doctors about the drug.

The manufacturer, Pfizer Inc., warned the public in a commercial, telling people who develop suicidal thoughts or actions to stop taking the drug and to call their doctor right away.

New advice coming

But Health Canada has been slower to act, posting a warning on its website months after the FDA issued its warnings. In January, the department promised to add an even stronger warning on the label.

In an email to CBC News, Health Canada said that "new advice for health professionals and Canadians will come in the near future."

Pfizer Canada said that "based on the totality of data, Pfizer stands by the efficacy and safety profile of Champix when used as directed."

Gayle Nakamoto would like to see more testing of the drug. Her ex-husband Thom Jancewicz killed himself in early January. The 48-year-old engineer was about to start a new job, and was taking Champix to quit smoking.

Nakamoto's 14-year-old daughter Ellaina Jancewicz keeps a journal dedicated to her father, as she tries to cope with her loss.

"What will I do now? I have no father," Ellaina said, reading from the journal. "I'm here with my mother alone and my brother. I'm very confused. I'm not sure what to do."

Nakamoto said her husband had problems with depression, but they seemed to be under control.

"I think the safer thing would be to take it off the shelf," said Nakamoto. "If there are people that are having serious side-effects … you don't want anyone to have to go through what we're going through."