The deaths of 12 Japanese children who had taken Tamiflu is to be discussed on Friday by a U.S. government committee conducting a routine annual review of the safety of the anti-flu medication and seven other drugs.
The deaths are detailed in a Tamiflu pediatric safety update released in advance of the meeting. There have been no reports of deaths in the United States.
The update also includes reports of 32 "neuropsychiatric events," all but one experienced by Japanese patients. Those cases included delirium, hallucinations, convulsions and encephalitis.
"Clearly, any time you get a report of a death or a serious occurrence, you want to look into it," said Dr. Murray Lumpkin, the deputy commissioner of the U.S. Food and Drug Administration. "Going into the discussion tomorrow, based on the information we have right now, we cannot say definitively there is a causal relation between the drug and the children's death."
The FDA sought and received more information from the Swiss pharmaceutical company Roche and Japanese health authorities about the deaths in advance of Friday's meeting, but has not initiated any action, spokeswoman Susan Bro said.
Complicating the issue is that many of the death and adverse reaction reports list symptoms commonly associated with the flu, Lumpkin said.
"It is very difficult, when the underlying disease causes what it is being reported, to figure out: Is it the underlying disease? Is it the drug?" said Lumpkin, adding that "millions and millions" of patients have safely used the drug to treat the flu.
A Roche spokesman did not immediately return an e-mail message seeking comment. Roche has supplied the FDA with two additional studies it commissioned that evaluated the safety of Tamiflu in pediatric patients.
Japan's Health Ministry warned last week that Tamiflu can induce "strange behavior" after reporting that two teen boys died shortly after taking the medicine.
"Roche has carefully reviewed these events and has concluded that a causal link cannot be established," the company said in a statement released on Monday.
However, the Japanese distributor of the Roche-patented drug told health officials it could not rule out a link between Tamiflu and the deaths. Tamiflu is extensively used to treat children in Japan, according to the FDA.
The U.S. labeling for Tamiflu lists nausea and vomiting as its most serious side effects. It labeling in Japan includes any adverse effects that have been reported — including impaired consciousness, abnormal behavior and hallucinations — regardless of whether they can be attributed to the drug, according to Roche.
Tamiflu is one of the few drugs believed effective in treating bird flu, which health officials fear could spark a pandemic should it mutate into a form easily passed from human to human.
