Tamiflu to carry warning about abnormal behaviour

The Food and Drug Administration in the U.S. (FDA) is recommending that patients who take Tamiflu be closely monitored for signs of abnormal behaviour.

The announcement is the latest update on the drug which is currently the first line of defence should a bird flu pandemic erupt, and comes as a result of 12 deaths and psychiatric symptoms among users in Japan.

Of the 103 reported new cases of delirium, suicidal behaviour and other mental problems between August 2005 and July 2006, three cases were fatal.

Ninety five of the cases were apparently Japanese children treated with the drug.

The agency's review found that of the 12 deaths there was one suicide, four cases of sudden death and four cases of cardiac arrest.

There were 32 reports of psychiatric "events" among children, including hallucinations and abnormal behaviour and in two cases a 12-year-old and 13-year-old jumped out of second-floor windows of their homes after taking the medication.

The U.S. and European agencies have emphasised that no causal link has been identified between the use of Tamiflu and reported deaths and the FDA says the updated label was "intended to mitigate a potential risk associated with Tamiflu".

The FDA recommends that close monitoring begin immediately after starting treatment with the drug because of the reports.

The U.S. labels will in future be more in line with the Japanese which already carry a warning that abnormal behaviour could occur.

The current FDA-approved labels only mention that "seizure and confusion" are seen in some patients.

Tamiflu is made by the Swiss pharmaceutical company Roche who deny there is any evidence the drug causes such neuropsychiatric adverse effects.

Both Roche and the FDA agree that severe cases of the flu can spark the abnormal behaviour reported and now list that on the updated labels.

As the drug could be of paramount importance should a pandemic occur, there has been a certain reluctance on the part of health officials in taking any action that might discourage people from taking Tamiflu.

Although Tamiflu does not prevent flu it can reduce the length and severity of its symptoms.

Japan is the biggest user of Tamiflu in the world, according to FDA, between 2001 and 2005, Tamiflu was prescribed 24.5 million times in Japan, compared with just 6.5 million in the United States.

The number and nature of the newly reported cases, with the comments from doctors who believe the behaviour was associated with the drug, keep the FDA from ruling out Tamiflu as the cause.

Tamiflu is recommended for 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.