The maker of the antiviral medication Tamiflu issued a new warning for the flu drug Monday, saying patients must be closely monitored for potential psychiatric problems, including delirium and suicide.
Hoffman-La Roche Inc. had been discussing the matter with the Food and Drug Administration, which has been reviewing 103 cases in which patients reported bizarre behavior, usually within a day of taking Tamiflu.
Most cases involved children under 17 and occurred in Japan. The cases include three people who fell to their deaths after taking the drug, including a 14-year-old boy who climbed atop the railing of his family's condominium, an FDA memo says.
The memo also cites the case of an 8-year-old in Japan who took one dose of Tamiflu and, about an hour and a half later, tried to run out the front door of his home. The child would not answer to his name and was growling, according to the memo, which was prepared in advance of an FDA pediatric advisory committee meeting Thursday.
Dr. Debra Birnkrant, director of the FDA's division of antiviral products, said it was not yet known if the abnormal behavior was caused by the drug or the flu, which can cause fever and delirium.
But she added, "Since there were a number of cases over the last year that we looked at, we thought it would be the prudent thing to make the public aware."
Another drug for seasonal flu, amantadine, has been associated with similar neurological side effects, mostly in the elderly, Birnkrant said.
Hoffman-La Roche said in a statement that reports of psychiatric side effects from Tamiflu were rare. "While any relative contribution of Tamiflu to these events is unknown, Roche is committed to working closely with the FDA to ensure that the product label accurately reflects the reports," it said.
The FDA's memo says 24.5 million Tamiflu prescriptions were filled in Japan from 2001 to 2005. In the U.S., 6.5 million prescriptions were filled in the same period.
Tamiflu is one of four treatments for seasonal flu in the U.S. It is usually taken to prevent or lessen the severity of the virus.
Many governments, including that of the U.S., have stockpiled the drug to combat a possible outbreak of the H5N1 avian influenza virus. Although that mainly infects birds, there have been 153 human deaths worldwide since 2003, according to the World Health Organization.