Why is the smoking cessation drug Chantix still on the market?

Consider that over the last five years, the Food and Drug Administration (FDA) has received 544 reports of suicide among those taking the drug and 1,869 reports of attempted suicide, according to a report by Al Jazeera America which filed a Freedom of Information Act request to tally up the number of adverse events reported so far.

The drug has been linked to aggressive behavior, psychiatric events and depression since it entered the U.S. market in 2006. When the Institute for Safe Medical Practice (ISMP) found Chantix (varenicline) had more adverse events than any other drug on the market, the Federal Aviation Administration released its health advisory that air traffic controllers and pilots were banned from using the drug. Truck drivers were banned from its use as well as members of military missile crews.

Courtesy of the World Health Organization. Russian anti-smoking advertisement from the 1980s.

The ISMP found that Chantix outbursts consistently had three characteristics – violence that was senseless and unpredictable, the victim was often chosen at random, and the violence was perpetrated by people with no history of violence.

The FDA is between a rock and a hard place. Smoking is a known environmental carcinogen and Chantix does seem to help smokers quit. Twenty-two percent of smokers quit smoking after 12 months while on Chantix, but that was only slightly better than other nicotine replacements. Still the agency has not confirmed Chantix, marketed by Pfizer, is actually the cause of the violence outbursts.

An FDA-sponsored epidemiological study released in 2011 failed to establish a link between the drug and neuropsychiatric hospitalizations when compared to other cessation drugs such as nicotine replacement therapy (NicoDerm).

Chantix works by blocking the effects of nicotine on the brain. The manufacturer says there were more than 21 million prescriptions for the drug over a five year period from 2006 to 2011. Last year the company made $670 million in sales, reports the news network.

Even after spending $300 million to settle 2,700 lawsuits filed by users of Chantix, Pfizer is still in the black when it comes to Chantix sales.

In 2009 the FDA required a boxed warning about hostility, aggression, depression and suicidal thoughts be added to the label of Chantix and a similar drug, Zyban. That’s the most serious warning issued by the FDA.

The FDA concludes that, for the time being, the drug label on Chantix remains appropriate while Pfizer conducts the largest clinical trial yet on the drug. But don’t hold your breath on results anytime soon. Pfizer is expected to issue the clinical trial results in the year 2017.