The FDA issued the Advisory to alert health care providers, patients, and caregivers to new safety warnings concerning Chantix (varenicline), a prescription medication used to help patients stop smoking. Chantix is manufactured by Pfizer Corporation.
According to the FDA, in most cases, neuropsychiatric symptoms developed during Chantix treatment, but in others, symptoms developed following withdrawal of Chantix therapy.
FDA officials said that they have received 34 reports of suicides and 420 of suicidal thoughts or behaviors, in the U.S., possibly linked to Chantix. They also received 39 reports of suicides and 491 reports of suicidal thoughts globally. (DJ FDA Issues Public Health Advisory on Pfizer's Chantix, Dow Jones Newswires, February 1, 2008). According to Pfizer, more than four million people have used Chantix.
"As FDA's review of the issue has progressed, it appears increasingly likely that there is an association between Chantix and serious neuropsychiatric symptoms", the FDA stated in today's advisory.
Chantix (varenicline) was approved in the U.S. in May 2006, and is available, only by prescription. It works by reducing the severity of a smoker's urge to smoke.
The FDA first informed the public about the possibility of serious neuropsychiatric symptoms in the November 20, 2007 FDA Early Communication About an Ongoing Safety Review. At that time, information about serious neuropsychiatric symptoms in patients taking Chantix was added to the POST-MARKETING EXPERIENCE section of the prescribing information.
The European Medicines Agency (EMEA) concluded this past December that updated warnings to doctors and patients were needed to increase awareness of cases of suicidal ideation and suicide attempts reported in patients using Chantix (marketed as Champix in Europe).
The Committee for Medicinal Products for Human Use (CHMP) which had been closely monitoring the safety of Chantix for the EMEA recommended that the following wording be inserted in the warning section of the SPC:
'Depressed mood may be a symptom of nicotine withdrawal. Depression, including suicidal ideation and suicide attempt, has been reported in patients undergoing a smoking cessation attempt. These symptoms have also been reported while attempting to quit smoking with Champix. Clinicians should be aware of the possible emergence of significant depressive symptomatology in patients undergoing a smoking cessation attempt, and should advise patients accordingly.'
Pfizer said last month that it would update the product label for Chantix, in order to better display the adverse events added, in November, to the POST-MARKETING EXPERIENCE section.
Today, the FDA requested that Pfizer add this safety information to the WARNINGS and PRECAUTIONS sections of the Chantix prescribing information, so that healthcare professionals and patients can be more alert to these issues. Pfizer and the FDA are also working to finalize a Medication Guide for patients.
Healthcare Providers were advised to monitor all patients taking Chantix for symptoms of serious neuropsychiatric symptoms, such as changes in behavior, agitation, depressed mood, suicidal ideation, and suicidal behavior.
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The advisory notified patients that Physicians who prescribe Chantix should discuss with them, their families, and caregiver any history of psychiatric illness prior to starting Chantix. Additionally, the advisory warns that vivid, unusual, or strange dreams may occur while taking Chantix. Patients are advised to be alert to changes in mood or behavior after starting Chantix and immediately report them to their doctor.
In the meantime, the FDA will continue to review new information it receives on Chantix and may consider additional regulatory action as the data review and conclusions warrant.