Mefloquine, an anti-malarial drug used for years by U.S. troops as well as some civilians heading to tropical hot spots, can cause long-term neurological damage and serious psychiatric side effects, according to the Food and Drug Administration.
The FDA warning, made public Monday in a safety announcement, is likely to be raised in the upcoming sentencing of U.S. Army Staff Sgt. Robert Bales for murdering 16 Afghan civilians. John Henry Browne, Bales' attorney, says the soldier took mefloquine on earlier tours of duty in Iraq.
The FDA announcement said the side effects can include feeling anxious or mistrustful, having hallucinations, loss of balance and dizziness. The safety notice said the information would be included in a boxed warning on labels -- the most serious kind about potential problems.
Even though Browne does not have medical records of any of Bales' Afghanistan prescriptions, he hasn't ruled out the possibility Bales took the drug before carrying out the March 2012 massacre.
"We're all over this," said Browne of the FDA warning. "This is an interesting development."
An Army sanity board already has concluded Bales did not suffer from any serious mental diseases or defects at the time of the killings and that he could understand the court-martial proceedings that led to a plea agreement earlier this year.
At the sentencing hearing, an Army panel of jurors is expected to decide whether Bales should receive a life sentence without the possibility of parole or eventually be eligible for consideration to be released from prison.
Browne said that during the hearing, scheduled to begin Aug. 19, he would consider raising the issue of Bale's mefloquine use.
The drug warning also could bolster the claims of some veterans who have attributed long-term health problems to mefloquine use and have sought disability benefits from the Department of Veterans Affairs.
"This certainly points to the need for the VA to develop some process to better study the neurological effects and come up with a way to evaluate these claims. There are veterans suffering from this," said Dr. Remington Nevin, a former Army doctor and epidemiologist involved in extensive research on mefloquine, including documenting the case of one sailor who suffered a brainstem injury.
Nevin said that earlier this year he and several veterans met with FDA officials to talk about their concerns, which may have helped prompt Monday's safety announcement.
"They asked me to present some of the neurotoxicity research on the drug," Nevin said, "and I'd like to think they decided that it was time to be frank about the risks."
Mefloquine initially was developed by the Army and once was marketed in the United States under the brand name Lariam, by Roche. Currently, only generic forms of the drug are marketed in the United States.
In recent years, amid increased concerns about side effects, use of the drug in the United States has dropped.
About 119,000 prescriptions were written for the drug during the first six months of this year, compared with 2.4 million prescriptions for the most common antimalarial drug, according to The New York Times.
Though mefloquine has continued to be used by some U.S. military personnel in Afghanistan, the Defense Department in a 2009 memorandum made the drug the third choice behind other drugs for anti-malarial protection for U.S. troops.
The prospect that Bales may have taken the drug in Afghanistan, as well as in Iraq, was raised earlier this month by the FDA's release of an "adverse event" notification filed by an anonymous pharmacist in spring 2012.
His report, obtained under the Freedom of Information Act, stated that an unnamed soldier who took the drug murdered 17 Afghan civilians, the same death toll included in Bales' initial charging documents.
Browne is skeptical of that report. He says Bales doesn't recall what drugs he took in Afghanistan and that medical records for that deployment are incomplete