Smoking-Cessation Pills by Pfizer and GSK Do Not Increase Risk of Suicide, Study Finds

A randomized, double-blind, placebo-controlled study conducted across 16 countries over a 3-year period has confirmed that Chantix and Zyban do not increase the risk of suicidal behavior among users.

Following its approval in 2006, Chantix (varenicline), manufactured by Pfizer, was thought to increase the risk of serious mental health events among consumers of the pill, which resulted in a significant reduction in the drug’s sales, according to STAT, from $846 million in 2008 to $671 million in 2015. Zyban (bupropion), manufactured by GSK, also faced similar charges. Additionally, consumer groups urged the FDA to include black box warnings on the drug packaging that would caution consumers on the psychiatric effects of the drug.

Consequently, the FDA ordered both companies to conduct a study to evaluate the neuropsychiatric effects of their products in smokers who have preexisting psychiatric disorders.

The study, published in Lancet, was conducted among 8144 participants, 4116 of whom were in the psychiatric cohort and 4028 in the non-psychiatric cohort. These were smokers who were motivated to quit, and they underwent counseling sessions at each visit. The primary trial endpoint was the incidence of a composite measure of moderate and severe neuropsychiatric adverse events. The main efficacy endpoint was biochemically confirmed continuous abstinence for weeks 9 to 12. Participants received either Chantix, Zyban, a nicotine replacement patch, or dummy pills for 12 weeks and then were followed for another 12.

The study found that among participants without psychiatric problems, the risk of suicidal thoughts or behavior or other serious mental health issues was very low and statistically the same: about 1.3% for those taking Chantix, 2.2% with Zyban, 2.5% with the nicotine patch, and 2.4% with a dummy pill. Among those with psychiatric problems, the risks were higher across the board: about 6.5% for Chantix and Zyban and 5% for the nicotine patch and dummy pill.

The authors conclude that neither drug caused a significant increase in neuropsychiatric adverse events compared with the nicotine patch or the placebo.

Pfizer plans to ask the FDA to remove the black box warning, according to STAT, while an FDA spokesman said that there will be continued evaluation of the issue.

Zyban was approved in 1997, but its patent expired about a decade ago. Bupropion is now available as a generic; Chantix faces patent expiration in 2020 in the United States. The new results raise the potential for Pfizer to make up for the significant losses faced by the company over the past few years.

Reference

Anthenelli RM, Benowitz NL, West R, et al. Neuropsychiatric safety and efficacy of varenicline, bupropion, and nicotine patch in smokers with and without psychiatric disorders (EAGLES): a double-blind, randomised, placebo-controlled clinical trial [published online April 22, 2016]. Lancet. doi:http://dx.doi.org/10.1016/S0140-6736(16)30272-0.