“Based on a review of the cases, there appears to be a syndrome of debilitating symptoms that interfere with people’s ability to function in their daily lives that is associated with the use of Chantix,” Dr. Winchell said.
The company agreed that the spontaneous reports in late 2007 raised concerns about whether the drug was associated with an increase in serious neuropsychiatric events. But since 2009, this issue has been evaluated in controlled studies, which “consistently show no evidence of an increased risk,” Dr. Christopher Wohlberg, the head of Pfizer’s safety surveillance and risk management group, told the panel.
These include a meta-analysis of adverse events in 18 controlled studies of about 5,000 patients treated with varenicline and about 3,500 on placebo, which found no significant difference in the rate of neuropsychiatric events (with the exception of sleep disorders and disturbance) among those on the drug vs. those on placebo; and a meta-analysis of 5 placebo-controlled studies that used the Columbia-Suicide Severity Rating Scale to evaluate suicidal ideation and behavior, which also found no significant differences between the two groups.
In addition, four observational studies that included patients with psychiatric illnesses showed that the rates of serious neuropsychiatric events in patients treated with varenicline were not significantly different from those treated with nicotine replacement therapy or bupropion for smoking cessation. In individual studies of patients with psychiatric illnesses (schizophrenia, schizoaffective disorder, or major depressive disorder), no evidence was found of an increased risk among those treated with varenicline, compared with those on placebo, according to the company.