An advisory panel to the agency voted against the removal this wee,k but agreed to revisit the issue once data from Pfizer's post-marketing study for Chantix (varenicline) is available. 

 

The firm is currently conducting a study on 8,000 people comparing Chantix with two other smoking-cessation treatments and a placebo in terms of possible serious neuropsychological effects. Data from the study is expected in the third quarter of 2015.

 

Steve Romano, senior vice president of Pfizer's global innovative pharmaceutical business, told Reuters: “I'm hoping the data confirms all the information we already have.”

 

The FDA placed a black box warning - its most severe and restrictive warning - on the product in 2009, highlighting the possibility of mental health issues found in patients using the drug, including depression and suicidal thoughts.

 

The National Centre for Health Research (NCHR) is one of five non-profit organisations that had filed a citizen petition asking the FDA to include risks of aggression, violence, psychosis and depression in the black box warning.

 

Diana Zuckerman, president of the NCHR, called the drug's side effects “distinctly worrisome”.

 

Analysts have said the retention of the warning label is not expected to have an impact of Pfizer's sales or profits. Chantix was Pfizer's 15th best selling drug of 2013.