The added precaution comes after reports of more than 100 new cases of delirium, hallucinations and other unusual psychiatric behavior in children treated with the drug. Most were Japanese children.
The Food and Drug Administration said a relationship between the drug and the behavior had not been established and that the updated label was “intended to mitigate a potential risk associated with Tamiflu.” It recommends that close monitoring begin immediately after starting treatment with the drug.
FDA said it had received 103 reports, mostly from Japan, of injury and delirium among the millions of flu patients treated with Tamiflu. The changes bring the U.S. label more in line with the Japanese one, which already warned such abnormal behavior could occur. The previous FDA-approved label mentioned “seizure and confusion” seen in some patients.
Tamiflu is made by the Swiss pharmaceutical company Roche Holding AG. Roche spokesman Terence Hurley said there was no evidence the drug caused the rarely occurring adverse events.
Both Roche and the FDA also said that severe cases of the flu can spark the abnormal behavior flagged in the updated label.
The surprise change came three days before an FDA panel of outside experts was to discuss whether to recommend that the agency add the precautionary language to the Tamiflu label. In documents released Monday, FDA staff acknowledged that stopping treatment with Tamiflu could actually harm influenza patients if the virus is the cause of delirium, hallucinations and other abnormal behavior, such as aggression and suicidal thoughts.
Last year, the same advisory committee rejected making any such changes to the label. At that time, however, the committee did recommend that the FDA continue to monitor the drug’s safety and return a year later with an update.
Health officials have been sensitive about taking any action that might dissuade people from taking Tamiflu, since the drug could play an important role in an outbreak of bird flu. The drug doesn’t prevent flu but can reduce the length and severity of its symptoms.
Previously, Roche has cited studies from the United States and Canada that show the death rate of influenza patients who took Tamiflu was far below those who did not.
Most of the new cases of bizarre behavior are from Japan, where Tamiflu usage is the highest in the world. Between 2001 and 2005, Tamiflu was prescribed 24.5 million times in Japan, compared with just 6.5 million in the United States, which has more than twice the population, according to FDA. However, FDA believes U.S. usage could increase to Japanese levels.
The new cases occurred between Aug. 29, 2005, and July 6, 2006. The tally marks a sharp increase when compared with the 126 similar cases logged over more than five years between the drug’s approval in 1999 and August 2005, the FDA said.
Even though severe cases of the flu can spark abnormal behavior, the number and nature of the newly reported cases — along with comments from doctors who believe the behavior was associated with the drug — keep the FDA from ruling out Tamiflu as the cause, according to agency documents.
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.
According to the label, Tamiflu is for 바카라사이트 the treatment of uncomplicated acute illness due to flu in patients 1 year and older who have shown symptoms for no more than two days.