Study: Pfizer's Chantix does not increase risk of depression, heart attack in smokers

Pfizer ($PFE) has fought long and hard to get the FDA to backtrack on its smoking cessation drug Chantix, trotting out positive study data to convince the agency to revoke a black-box warning tied to serious psychiatric side effects. Now, the company is adding more ammo to its arsenal, with a new study that shows Chantix does not increase certain cardiovascular or psychiatric symptoms.

Scientists tracked 150,000 smokers in England over 6 months, and found that individuals who took Chantix--known as Champix in Europe--were no more likely to have a heart attack than people using nicotine replacement therapy or another quit-smoking drug, Reuters reports. And the individuals in the study were not at higher risk of depression or self-harm, the study suggested. In fact, researchers said, more people should probably be using Chantix, not fewer.

The findings are music to Pfizer's ears as it tries to change the FDA's stance on the med. After the company launched Chantix in 2006, reports began to surface that the drug could cause mental health problems in some users. In 2009, the agency slapped the drug with a black-box warning--its most serious safety designation. A couple years later, the FDA updated the label with further precautions.

Earlier this year, the agency voted to keep the black box on Chantix, which includes warnings about suicide and suicidal thoughts. The FDA also tacked on new cautionary advice about using Chantix with alcohol, pointing to cases where patients exhibited unusual or aggressive behavior while drinking. And a few patients experienced seizures, regulators said at the time.

But not everyone agrees with the agency. It's "highly unlikely that (Chantix) has any significant adverse effects on cardiac and mental health," Aziz Sheikh, professor and co-director of the University of Edinburgh's Centre for Medical Informatics, told Reuters. And the drug's safety warning "may be unnecessarily limiting access to this effective smoking aid," he added.

This is exactly the kind of assessment Pfizer is looking for with Chantix, which brought in $647 million in worldwide sales last year, with $377 million of that haul in the U.S. Since the original FDA warning, the company has been trying to change the agency's tune by proffering new study data.

In February, a new study published in the Journal of the American Medical Association found that smokers who wanted to quit but couldn't go cold turkey were more likely to stop smoking with Chantix than a placebo. Up to 14 million current smokers could fit the same profile as study participants, the study authors noted at the time, a potentially big patient pool for Pfizer.

The company is also waiting on results from an FDA postmarketing safety study that will provide more data on Chantix. The agency will release an update "as appropriate" when new information becomes available, it said earlier this year.

- read the Reuters story

Special Reports: The top 10 most-advertised prescription drug brands - Chantix | The top 15 pharma companies by 2014 revenue - Pfizer

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