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(Adds details on drug, FDA recommendation)
By Natalie Grover
Sept 14 (Reuters) - A serious warning on Pfizer Inc's quit smoking drug should be removed, 10 of 19independent panelists to the U.S. Food and Drug Administrationrecommended on Wednesday, after reviewing additional trial dataon the controversial treatment.
Pfizer's Chantix was approved about a decade ago, butthousands of reports of mental health problems in users led tothe FDA imposing the "black box" warning - the most severeavailable - in 2009.
On Wednesday, four of the 19 panelists voted to update thelanguage in the box warning - of neuropsychiatric risksincluding suicidal thoughts, hostility and agitation - whilefive recommended retaining it.
The 10 who voted in favor of removal stressed that thebenefits of quitting smoking far outweighed the potential severeside-effects of the drug, and that the evidence of causalitybetween Chantix and the side-effects was not clear enough towarrant a black box.
Cigarette smoking is the leading cause of preventabledisease and death in the United States, accounting for about 1of every 5 deaths, according to the U.S Centers for DiseaseControl and Prevention.
Pfizer failed a previous attempt to get rid of the boxedwarning, after the FDA went along with a panel recommendation in2014 to retain it pending the outcome of the additional study.
Since then Pfizer has released results from the study thatcompared either Chantix or GlaxoSmithKline Plc's Zyban,with a placebo or a nicotine patch in patients with and withouta history of psychiatric disorders.
FDA staff on Monday issued a scathing review of how thestudy was conducted by Pfizer, flagging multiple inconsistenciesacross the 140 sites and multiple countries in which data wascollected.
But when the FDA conducted its own analysis, excluding datathey deemed unreliable, the results appeared to be consistentwith Pfizer's conclusion that Chantix does not significantlyincrease the incidence of such side-effects.
The discussion among panelists on Wednesday ranged fromwhether certain adverse events were the result of tobaccowithdrawal or the drug, as well as the trend of a higher numberof psychiatric side-effects seen in patients with a history ofmental illness.
Patients with psychiatric disorders are far more vulnerableto tobacco addiction, and less likely to be prescribedtreatments for smoking cessation, they noted, saying that theexclusion of the boxed warning would go a long way in improvingstatistics.
Some panelists who voted to modify the warning or retain itin its present form, said they were fearful of setting adangerous precedent for other drugmakers looking to remove suchwarnings off of their products, or that Pfizer's implementationof trial design left a lot to be desired.
The FDA is not obligated to follow the recommendations ofits panel, but typically does so. (Reporting by Natalie Grover in Bengaluru; Editing by DonSebastian and Andrew Hay)
