Pfizer’s anti-smoking drug Chantix to carry black-box waning till availability of study data

Pfizer Inc failed to convince the US Food and Drug Administration to remove a black-box warning on its quit-smoking drug Chantix, after an advisory panel to the agency voted against the removal today, Reuters reported.

A majority of the panel voted in favour of retaining the health regulator's most severe warning label on the treatment, in line with the recommendations of FDA staff members two days earlier.

The panel agreed to revisit its stand once data from Pfizer's post-marketing study of Chantix was available.

The drugmaker is conducting a study involving 8,000 people comparing Chantix's serious neuropsychological side effects with two other smoking-cessation treatments and a placebo.

The study data would be available in the third quarter of 2015.

Chantix, or varenicline as it is also known, is one of the most controversial drugs from the company. The drug has a number of severe side effects, including suicidal thoughts and erratic behaviour.

In 2009, the FDA had placed its most severe and restrictive warning, a black-box warning on the product, highlighting the drug's adverse neuropsychological effects.

According to Pfizer, new data indicated the risk of suicidality and other serious psychiatric events was not as great as once thought, and had applied to the FDA to remove a boxed warning on those risks.

However, in briefing documents for the FDA advisory committee meeting, members of the agency's technical staff said those data had major limitations and that, at least for now, the boxed warning should stay.

Members of the FDA's Psychopharmacology Drugs Advisory Committee and its Drug Safety and Risk Management panel would meet jointly to review the matter.

The staff recommendation called for holding on till an ongoing, prospective trial aimed at determining varenicline's psychiatric risks was completed next year before deciding whether the boxed warning overstated the actual risk.

The initial approval for Varenicline was granted in 2006 and the following year, regulators started seeing signals in adverse-event reporting systems of increased suicidality -- thoughts, attempts, and completed suicides -- associated with the drug.

Over 260 such events were reported to the FDA within 18 months of approval.