champix brain illustration
© unknown

The Champix mechanism, to this reporter's lay reading of the literature, binds to the receptors in your brain that trigger the release of dopamine and eventually suppresses its production. This is similar to the action of SSRIs, which are also receptor agonists, but for seratonin rather than nicotine. So it shouldn't come as that much of a surprise if it had similar psychiatric side-effects to those of Prozac, Effexor, etc. These receptors have some natural function that's being degraded, after all. Hostility? Suicidal thoughts? You pay your money and you take your chance.
The Globe and Mail
Carly Weeks
January 9, 2009

Health Canada has received more than 800 reports of side effects - including more than 500 reports of psychiatric problems - linked to the controversial smoking-cessation drug Champix in less than two years on the market.

But although evidence is growing that the medication is linked to aggression, depression and suicidal tendencies, some tobacco-control experts and non-profit groups in Canada still encourage its use, often without mention of the possibility of psychiatric problems.

In its online guide to quitting smoking, forexample, the Canadian Lung Association includes a section that lists Champix first as an effective option to "reduce cravings and withdrawal symptoms."

The association says the "pros" of Champix include the fact it is in pill form and is easy to use, as well as the fact it is not addictive because it doesn't contain nicotine. The guide lists only minor side effects, such as nausea, strange dreams and constipation, as "cons" to taking Champix, even though Health Canada has issued two warnings in recent months about links between the drug and serious psychiatric side effects.

The smoking and tobacco section of the website indicates that Pfizer Canada, which sells Champix, provided funding to the association in the form of a restricted educational grant, which means that Pfizer isn't involved in how the money is spent.

Lung Association spokesman Cameron Bishop said the organization is aware that Health Canada is in the process of strengthening its warning on Champix.

The association "is [in] the process of updating tobacco-cessation content on our website to reflect the new information," Mr. Bishop wrote in an e-mail. "We remain committed to ensuring that Canadians who want to quit smoking have the best possible information on all available smoking-cessation options approved by Health Canada."

The Canadian Cancer Society's quit-smoking guide also alludes to the effectiveness of Champix, one of two approved smoking-cessation pills on the market in Canada, but doesn't mention it by name.

Some doctors and tobacco-control experts who receive research or other funding from Pfizer sometimes promote the benefits of Champix without mentioning safety concerns.

Controversy over the safety of Champix has been brewing in Canada and internationally since shortly after the drug was introduced to the market.

Last June, Health Canada issued its first warning on the drug, advising the public and health-care professionals that it had received more than 200 reports of psychiatric problems, including hostility and suicidal thoughts, linked to Champix. The warning followed an earlier one issued by U.S. health authorities.

The safety warning issued on Champix in the U.S. (where the drug is sold under the name Chantix) had a dramatic impact on sales. The company said third-quarter Chantix revenues in the U.S. plummeted 49 per cent last year compared with the same period the year before. The drop was attributed to the safety warning issued in February, 2007. However, the drug's international third-quarter revenues jumped 60 per cent compared with the same period in 2007.

Earlier this week, Health Canada issued its second warning about the product to ensure the risks were being communicated to the public. It also announced it is in the process of creating a stronger warning label to better reflect potential health risks.

Champix was put on the Canadian market in April, 2007. From its introduction until Oct. 31, 2008, Health Canada received 818 reports of adverse reactions associated with the medication, spokesman Paul Duchesne wrote in an e-mail.

Of those, 520 reports were linked to psychiatric problems.

Pfizer Canada said it considers the drug safe and efficacious for people who are looking to quit smoking.

Although the drug may pose some health risks to some, Health Canada said the link between Champix and psychiatric problems hasn't been proven. The overall benefits of the medication outweigh the potential risks, but Canadians considering taking it should be aware of the safety issues, Health Canada said in its public advisory this week.