The injectable drug is used to prevent excessive blood loss during heart surgery brought on by the blood thinner heparin and mechanical tubing used in the heart-bypass machine.
The FDA had approved it in 1993 to stanch the loss of blood and prevent the need for blood transfusions in surgeries to bypass clogged coronary arteries.
A joint panel of FDA expert advisers voted Wednesday 6-1, with one abstention, to recommend allowing sales of the drug to continue, an agency spokeswoman said. The FDA is not required to follow the advice of its advisory committees but does so most of the time.
The FDA has been re-evaluating the drug's safety since the January 2006 publication of two studies that linked the drug's use to serious side effects, including kidney problems, heart attacks and strokes.
More recent studies, including one done by Bayer themselves, have suggested the drug also raises the risk of death.
Bayer said Trasylol has been shown to reduce the risk of blood transfusion. The company allows that the drug appears to be associated with kidney dysfunction, but says any link to kidney failure is less definitive, according to documents released ahead of Wednesday's meeting.
The company said data do not show any increased risk of death in using the drug and cited a continuing study that is examining in part the stroke, heart attack and other risks.
The FDA in December strengthened the already severe "black-box" warnings on the drug to say it should be used only in patients who face an increased risk of blood loss and transfusion during bypass surgery. At the time, it left open the possibility of further warnings.
Trasylol works by blocking enzymes that dissolve blood clots.
Two surgeons said that Trasylol was a good option to help restore normal blood clotting in patients at increased risk for bleeding complications because of reversibility problems. These patients, said Dr Robert Higgins at Rush Presbyterian St. Luke's Medical Center in Illinois and Dr Grayson Wheatley at the Arizona Heart Institute, primarily include those expected to be on the heart-bypass machine for an unusually long time, the elderly, those who have had the surgery before and patients with kidney problems or other medical issues that put them at increased risk for bleeding after surgery.
"Heart surgeons use this medication selectively," Wheatley said, characterizing about 20% of heart-bypass patients as falling into this higher-risk category. "It's not something that we give routinely to every patient - there are suitable alternatives - but we do know that Trasylol is the most effective medication for restoring the clotting factors to their normal level in very high risk patients."
Explaining his endorsement, he said it restores every clotting variable to normal while other drugs only affect some of them, and he added that Trasylol was the quickest acting of such drugs. Those considered less effective were adequate in lower-risk patients, Wheatley said, given their more benign risk-benefit profile than Trasylol. But notably, he said the percentage of higher-risk patients undergoing heart-bypass surgery was on the rise, owing largely to new drug therapies and alternate procedures like stenting that help lower-risk patients avoid the operating room.
"It used to be that the only thing that we used to have was heart surgery," he said, "but now we only do heart surgery in complex cases or cases in which people don't respond to other therapies."
Higgins added that though there were alternatives to Trasylol, he said he preferred to have it as an option.
"In the appropriate patient, the drug has its place," he said. "Like any other medication, there are risks and benefits to its use, and we as physicians make informed decisions about the risks and benefits and try to come up with a strategy that enhances the patients' outcome."
Therefore, neither he nor Wheatley would like to see Trasylol fall under the regulatory guillotine and face a market withdrawal.