But the FDA reviewers raised issues with the meta-analysis of the 18 studies and the observational data. The observational data have limitations and “preclude” a conclusion that there is no association of varenicline and an increased risk of neuropsychiatric events, said Natasha Chen, Ph.D., an epidemiologist in the FDA’s office of surveillance and epidemiology. The ongoing postmarketing safety trial “is likely to offer better insights into varenicline’s neuropsychiatric risks,” she added.
The one panelist who voted to remove the warning, Dr. Andrew J. Saxon, said while there “may be some serious adverse or neuropsychiatric effects, the data, while not perfect,” do not show a signal in his view. He added that in his experience working daily with patients who are trying to quit smoking, “patients are afraid to take this medication because of the boxed warning, and it does deter use.” Moreover, in the Veterans Affairs system, there are restrictions on prescribing the drug because of the boxed warning, including a limitation on prescriptions to a 28-day supply, with no refills. Such restrictions increase hassles for patients and prescribers, and often result in patients stopping treatment after 4 weeks.
“If I’m doing a good job as a physician, I’m going to monitor the patient,” said Dr. Saxon, director of the addiction psychiatry residency program, University of Washington, Seattle.
The FDA usually follows the recommendations of its advisory panels, which are not binding. Members of these two panels had no conflicts to disclose. Occasionally, panelists with a conflict are given a waiver, but not at this meeting.
In a statement issued by Pfizer after the meeting, Dr. Steven Romano, senior vice president and head of the medicines development group for Pfizer, said the “completion of our currently ongoing safety study will represent one more step forward in the process of accurately characterizing the neuropsychiatric safety of this important medication.”
The varenicline label is available at http://labeling.pfizer.com/ShowLabeling.aspx?id=557. Serious adverse events associated with this drug should be reported to the FDA’s MedWatch program at http://www.fda.gov/Safety/MedWatch/default.htm.