Pfizer, who make the smoking cessation drug Chantix (varenicline), have updated the drug’s labelling in the United States to reflect the fact patients may experience “serious neuropsychiatric symptoms”, including suicidal behaviour.

Chantix was approved by the US Food and Drug Administration (FDA) in May 2006 as a prescription drug to help smokers quit.

Stressing that smokers who want to quit should receive counselling support, Pfizer’s action follows an early communication from the FDA last November that warned the drug could be linked to suicidal thoughts and behaviour. This was prompted by post-marketing results, and a label revision also ensued. However, this update is a more serious warning that:

“Patients who are attempting to quit smoking with CHANTIX should be observed for serious neuropsychiatric symptoms, including changes in behavior, agitation, depressed mood, suicidal ideation and suicidal behavior,” said Pfizer.

The drug company said this latest update was to ensure doctors and patients can better weigh up the benefits versus the risks of the various ways to quit smoking and the treatments available, including Chantix.

Pfizer stressed that studies have not shown Chantix caused these neuropsychiatric symptoms, but in some studies a link could not be excluded. They said that some results could have been confounded by the effect of nicotine withdrawal, but not all patients who had these symptoms had quit and some patients who already had psychiatric conditions got worse when they tried to stop smoking using Chantix.

Pfizer’s chief medical officer, Dr Joe Feczko said:

“There are few things that provide greater health benefits than quitting smoking. When considering the use of CHANTIX for their patients, healthcare providers should discuss the risks of smoking, the health benefits of quitting smoking, and the product’s efficacy and safety profile.”

Adding that the drug was a breakthrough medicine, with a track record in helping many smokers quit successfully, Feczko emphasized the importance of a well informed dialogue between doctor and patient, especially where prescription medication was being considered.

A placebo-controlled clinical trial involving over 5,000 patients, neuropsychiatric symptom such as behaviour changes, agitation, depressed mood, suicidal ideation, and suicidal behavior occurred as frequenlty among the Chantix group as the placebo group. The company stressed no suicides were attributed to Chantix in the trials, which did not include patients with serious psychiatric illnesses such as schizophrenia, bipolar and major depressive disorders.

Smoking is the leading preventable cause of disease and premature death in the US, where it accounts for more than 400,000 lives lost every year.

Chantix is classed as a selective nicotinic acetylcholine receptor partial agonist, and is the first smoking cessation drug that is not based on nicotine to come out in the last 10 years.

It helps people give up smoking in two ways: it gives the same feeling of satisfaction as nicotine and it blocks the effect of nicotine on the brain. The first effect lessens the symptoms of withdrawal, while the second stops nicotine from trigerring the brain’s reward center.

More than 4 million Americans have received a prescription for the drug since it won FDA approval in May 2006.

If you are thinking of quitting smoking, you will find many people ready with advice. One such source is the US government’s website They advise that you prepare to quit with S – T – A – R – T, which stands for:

SSet a date.
TTell people: friends, family, work colleagues.
AAnticipate and plan for the challenges you will face while quitting.
RRemove temptation: clear your home, car and work space of tobacco.
TTalk to your doctor and get good, well informed support.

Click here for resources on how to stop smoking (

Click here for fact sheet on smoking cessation from US Centers for Disease Control and Prevention (CDC)

Sources: Pfizer press statement, MNT archive, FDA.

Written by: Catharine Paddock