A lack of controlled case studies, combined with conflicting data and a voluntary system of reporting issues to Health Canada, make it impossible to say if a stop-smoking drug is triggering serious adverse reactions in some who are prescribed it.
These are among the findings of an RCMP toxicologist tasked by Manitoba prosecutors to probe the effects of the smoking-cessation drug varenicline (branded as Champix in Canada) on people when taken alone or in combination with alcohol.
The Crown requested the RCMP analysis as they geared up for a jury trial involving a Canadian Forces member who had been prescribed Champix, but went off it without consulting his doctor and wound up arrested in connection with a terrifying and out-of-character rampage on Oliver Street in October 2011.
The 29-year-old telecommunications linesman had no history of psychological problems, was qualified as a licensed restricted-gun owner and had only a minor assault conviction dating back many years.
His case has now been resolved in a plea deal after the Crown concluded there was a serious possibility many of the "specific intent" gun charges he faced were unprovable due to a potential he was in the involuntary throes of side-effects stemming from a combination of Champix and liquor at the time of the event.
In a four-page report tendered in court, Alberta-based RCMP toxicologist Angela Filbert outlines a history of available information about varenicline and its side-effects.
The most common adverse effects to varenicline were nausea, abnormal dreams and nausea, according to a 2007 clinical trial, she states.
But in addition, there have been reports of "serious psychiatric symptoms, including depression, aggression, agitation, suicidal tendencies and homicidal ideation," she added.
As well, she noted, U.S. food and drug officials issued a public health advisory warning users and doctors about the adverse affects. Health Canada issued a similar warning in mid-2008, according to the report.
Between April 1 and Nov. 23, 2007, a Health Canada adverse-reaction database received 107 reports suspected to be linked to varenicline, Filbert states.
Of those 107 reports, 48 described "adverse psychiatric effects." Fourteen of those involved aggression, depression or suicidal thoughts, said Filbert.
More than 708,000 Champix prescriptions were issued in Canada between April 2007 and 2008, the report states.
The current adverse-reaction reporting system for consumers and health professionals could be painting a misleading picture, Filbert suggests.
"There may be an under-reporting of adverse reactions since the reporting to Health Canada is voluntary," she states.
"In addition, consumer and health professionals' reports of adverse reactions... only suggest the possibilities of adverse reactions. This is because it is only based on observations of adverse reactions that are suspected to be associated with varenicline.
"Controlled studies are required to determine if varenicline is actually causing the adverse reactions," Filbert states.
As well, conflicting available data make it difficult to say whether the "psychiatric adverse effects" some people report -- such as depression, anger and anxiety -- are triggered by the drug or simply from quitting smoking itself and nicotine withdrawal, said Filbert.
There were no case studies as of December 2013 to show drinking alcohol while taking Champix increases the risk of experiencing "neuropsychological effects," she states.