Swiss drug maker Roche Holding AG says it is willing to accept a recommendation by a U.S. Food and Drug Administration panel to put a stronger warning label on its flu treatment drug Tamiflu.
But company spokesperson Martina Rupp says her company wants all patients to be warned that the illness itself can pose a risk of psychiatric problems, not just for those taking Tamiflu, the brand name for oseltamivir.
Tamiflu's label already mentions reports of delirium and self-injury, primarily among children in Japan, but the FDA panel recommended Tuesday that the language be changed to mention that several patients have died as a result of these abnormal behaviors.
The FDA typically takes the advice of its advisory panels.
Nearly 600 cases of psychiatric problems have been reported in Tamiflu patients, with 75 per cent of them coming from Japan. Five children there have died after falling from windows or balconies or running into traffic.
Tamiflu has been used by 48 million patients since its launch in 1999, many of them in Japan. Infectious disease expert Dr. Neil Rau tells CTV's Canada AM that the drug has not been as widely used in North America.
He notes that the rate of incidence of psychiatric problems is small.
"The more you use a drug, the more likely you're actually going to see a problem," Rau said. "If you have 40 million users and then have you 400 cases of neuropsychiatric adverse events -- in other words: mental change problems, hallucinations, problems thinking -- you're going to have those things described only when you had millions and millions of uses."
Rau also points out that it is possible that the infection itself -- the flu -- caused the psychiatric events, rather than the drug.
That point has been echoed by Roche, with spokeswoman Rupp stressing Wednesday that there was no causal relationship between Tamiflu and reported cases of delirium and hallucinations.
Rupp said influenza causes fevers that reach 104 Fahrenheit or higher, and people "need to know that this is associated with delirium and hallucination."
"It's important, really, that the label reflects that influenza itself can trigger such events," she said Wednesday.
Tamiflu sales totalled US$1.1 billion in the first half of 2007. Japan accounts for two-thirds of that.
Sales have benefited in recent years from governments stockpiling the drug in case the bird flu virus that has ravaged poultry stocks in Asia mutates into a form that can be easily transmitted among humans, sparking a flu pandemic.
Japanese health authorities are scheduled to hold their own meeting on Tamiflu's safety next month. Health authorities there issued a warning in March against prescribing Tamiflu to those aged 10 to 19, because of the reports of erratic behaviour.
