"Lab rat, guinea pig, disposable hero," said former US Army sniper James Elliott in describing how he felt he was betrayed by the Veterans Administration.
Elliott, 38, of suburban Washington, D.C., was recruited, at $30 a month, for the Chantix anti-smoking study three years after being diagnosed with Post Traumatic Stress Disorder. He served a 15-month tour of duty in Iraq from 2003-2004.
Months after he began taking the drug, Elliott suffered a mental breakdown, experiencing a relapse of Iraq combat nightmares he blames on Chantix.
"They never told me that I was going to be suicidal, that I would cease sleeping. They never told me anything except this will help me quit smoking," Elliott told ABC News and "The Washington Times".
It wasn't until three weeks later that the Veterans Administration advised the veterans in the Chantix study that the drug may cause serious side effects, including "anxiety, nervousness, tension, depression, thoughts of suicide, and attempted and completed suicide."
The VA's letter to the veterans, on February 29, 2008, followed three warnings from the FDA and Chantix' maker Pfizer, that were issued on November 20, 2007, January 18, 2008 and February 1, 2008. (click here to read the FDA warning and click here to read Pfizer's statement on Chantix)
"How this study continued in the face of these difficulties is almost impossible to understand," said Arthur Caplan, director of the Center for Bioethics at the University of Pennsylvania.
Doctors at the Veterans Administration say they acted as quickly as they could.
"This didn't justify an emergency warning at that level," said Dr. Miles McFall, co-administrator of the VA study.
Dr. McFall said there is no proof that Elliott's breakdown was caused by Chantix and he sees no reason to discontinue the study. Some 140 veterans diagnosed with Post Traumatic Stress Disorder continue to receive Chantix as part of a smoking cessation study.
Dr. McFall says the VA decided to continue the Chantix study because "it would be depriving our veterans of an effective method of treatment to help them stop smoking."
Caplan, one of the country's leading medical ethicists, said he was stunned by the VA's decision to continue the Chantix experiment.
"Why take the group most a risk and keep them going? That doesn't make any sense, once you know the risk is there," he said.
Chantix is one of the drugs being used in an estimated 25 clinical studies using veterans by the VA.
Pfizer maintains that "the benefits of Chantix outweigh the risks" and that it continues to do further studies on the drug.
The FAA has prohibited commercial airline pilots from using Chantix because of its possible side effects.