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FDA to Review Psychiatric Side Effects of Smoking-Cessation Drug Chantix (Varenicline)

Public meeting scheduled for October

According to an announcement posted April 25 in the Federal Register, the FDA will convene an advisory panel meeting on October 1 to discuss the risk of serious neuropsychiatric adverse events with Chantix (varenicline tartrate, Pfizer) tablets, and to review options for addressing this risk.

The agency intends to make background material available to the public no later than 2 business days before the meeting.

Chantix, a nicotinic receptor partial agonist, was approved in 2006 for use as an aid to smoking-cessation treatment. The FDA first began investigating the drug’s potential adverse effects the following year.

In 2009, a black box warning was added to the labeling for Chantix, citing a potential for serious neuropsychiatric events. The warning advises patients and caregivers that the patient should stop taking Chantix and contact a health care provider immediately 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 Chantix or shortly after discontinuing Chantix.

Pfizer recently submitted new data to the FDA comparing the drug’s psychiatric safety with that of placebo and other anti-smoking techniques.

In October 2011, the FDA announced that it had reviewed the results from two agency-sponsored epidemiologic studies that evaluated the risk of neuropsychiatric adverse events associated with Chantix. According to the agency, neither study found a significant difference in the risk of neuropsychiatric hospitalizations between Chantix and nicotine replacement therapy (NRT; e.g., NicoDerm patches).

The first study included 14,131 Chantix users and an equal number of NRT users. Sixteen psychiatric hospitalizations occurred among Chantix-treated patients, and 21 occurred among NRT patients (hazard ratio [HR], 0.76).

The second study compared the acute (30-day) rates of hospitalizations for neuropsychiatric adverse events among new users of Chantix (n = 19,933) or the NRT patch (n = 15,867) who started therapy from August 2006 to August 2007 in the Military Health System. Similar to the previous study, 18 psychiatric hospitalizations occurred among Chantix users, and 16 occurred among NRT users (HR, 1.13).

The FDA noted, however, that both trials had a number of study-design limitations, including assessing only neuropsychiatric events that resulted in hospitalization, and not having a large-enough sample size to detect rare adverse events.

Although the two studies did not suggest an increased risk of neuropsychiatric events that result in hospitalization, they did not rule out an increased risk of other neuropsychiatric events with Chantix, the FDA said.

Sources: Medical Xpress; April 25, 2014; Federal Register; April 25, 2014; Chantix Labeling; December 2012; and FDA; October 24, 2011.

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