The risk of being hospitalized for neuropsychiatric events was similar among people treated with the smoking cessation drug varenicline and those treated with nicotine replacement therapy, the Food and Drug Administration announced Oct. 24.
The agency’s conclusions were based on two epidemiologic studies reviewed by the FDA as part of its ongoing safety review of varenicline.
However, the two retrospective cohort studies evaluated only neuropsychiatric events that resulted in hospitalizations and were not large enough to detect rare events associated with varenicline, a nicotine receptor agonist, marketed as Chantix by Pfizer, the statement said. And although the studies "did not suggest an increased risk of neuropsychiatric events that result in hospitalization, they do not rule out an increased risk of other neuropsychiatric events with Chantix."
Still, based on the assessment of currently available data, "the agency continues to believe that the drug’s benefits outweigh the risks and the current warnings in the Chantix drug label are appropriate," and health care professionals should continue to follow the recommendations in the drug’s label, the statement said.
The FDA also recommends that clinicians ask patients whether they have any history of psychiatric illness before starting varenicline treatment – and should tell them to immediately stop taking the drug and contact a health care professional "if agitation, hostility, depressed mood, or changes in behavior or thinking that are not typical for the patient are observed, or if the patient develops suicidal ideation or suicidal behavior while taking or shortly after discontinuing Chantix."
Pfizer is conducting a large clinical safety trial that is assessing neuropsychiatric events as outcomes, but the results are not expected until 2017.
Since varenicline was approved by the FDA in 2006, serious neuropsychiatric events – including changes in behavior, agitation, depressed mood and suicidal thoughts or actions – have been reported in patients during and after treatment, and are described in a boxed warning and in the warnings and precautions sections of the drug’s label. These reports also have been described in previous FDA advisories, including in 2008 and in 2009.
One of the two observational studies sponsored by the FDA was conducted by the Department of Veterans Affairs’ Center for Medication Safety. This retrospective study compared mental health hospitalizations among people who started treatment with varenicline or nicotine replacement therapy between May 2006 and September 2007. (About 14,000 people were in each group.)
The second study was conducted by the Department of Defense U.S. Army Medical Command’s Pharmacovigilance Center, which compared the rates of hospitalization for neuropsychiatric events for 20 days after starting treatment with either varenicline (almost 20,000 patients) or the nicotine replacement patch (almost 16,000 patients), who started treatment from Aug. 1, 2006, through Aug. 31, 2007.
Between May 2006 through July 2011, about 21.8 million prescriptions for varenicline were dispensed and about 8.9 million patients have received varenicline prescriptions through outpatient retail pharmacies in the United States, the statement said.
Serious adverse events related to varenicline should be reported to the FDA’s Medwatch program, or by calling 800-332-1088.