Anti-smoking drug Chantix adds suicide to it's warning label

The anti-smoking drug Chantix, which was approved by the Food and Drug Administration (FDA) in May 2006, will in future carry a warning about the possibility of suicidal thoughts in patients who take it.

Drug company Pfizer has updated the drug's labelling after receiving hundreds of complaints about the drug's side effects.

The updated Chantix label will include a warning that patients taking the drug should be observed for serious neuropsychiatric symptoms.

These symptoms include changes in behaviour, agitation, depressed mood, suicidal ideation and suicidal behaviour.

According to the FDA such changes have often been reported within days or weeks of people first taking the drug.

Although the warning is similar to the one issued in November last year, it is more prominently displayed in order get the attention of doctors.

Chantix (Varenicline) has been on the market in the U.S. since August 2006 and has generated about $600 million in sales for Pfizer.

Last November the FDA announced that it is investigating at least one incident of a patient who died while being treated with Chantix.

Pfizer says there is no scientific evidence linking Chantix to depression and a causal relationship between Chantix and these reported symptoms has not been established.

The drug company says in some cases an association could not be excluded but the scenario has been complicated by the symptoms of nicotine withdrawal in patients who stopped smoking and also that not all patients with these symptoms had quit smoking.

Pfizer says in controlled clinical trials with more than 5,000 patients treated with Chantix, such changes in behaviour occurred at a rate comparable to placebo-treated patients and there were no suicides attributed to the drug.

Late last year, the European Medicines Agency (EMEA) said the drug should carry a warning about the high risk of suicide attempts among patients.

On a more optimistic note last year, researchers at the University of California, found in a study conducted on rats that Chantix might also reduce drinking addiction.