FDA attaches new Warning with Tamiflu

Tamiflu, an antiviral drug that is used in the treatment of both Influenza virus A and Influenza virus B, has been linked with hallucinations and other abnormal behavior in people taking the medication.

A new warning label was added to the drug by the US Food and Drug Administration (FDA) on Monday after more than 100 cases of unusual psychiatric effects, including cases of self-injury and suicide, were reported.

It was also seen that such side effects was noted more in children than adults and the FDA has advised the parents to watch out for such reactions in their children when treating them with the antiflu drug.

"The reports were primarily among paediatric patients," the FDA website says. "Patients with influenza should be closely monitored for signs of abnormal behaviour throughout the treatment period," it adds.

The FDA informed that 95 out of 103 cases of hallucinations were reported in Japan, the biggest user of Tamiflu, especially among children and adolescents. About 60% of the affected patients were under 17 and in some cases suicide was also reported. At least 12 children taking the drug died in Japan last year.

Although, the FDA has updated the label of the drug after various cases were reported, they have yet not established a strong relationship between the drug and the behavior and hold that severe cases of flu could have sparked the side-effects.

Previously, the label had only mentioned that “seizure and confusion” have been seen in some patients.

With increasing fears about the potential for a new influenza pandemic, millions of doses of Tamiflu have been stocked by the Governments and World Health Organization.

Oseltamivir, which has been used to put a stop to new viruses from emerging from infected cells, was developed by Gilead Sciences and is currently marketed by Hoffmann-La Roche (Roche) under the trade name Tamiflu. It is the first orally active neuraminidase inhibitor commercially developed.

After various cases of psychological disorders and several fatalities were reported between 2000-2004, the safety division of health ministry of Japan ordered changes to the label of oseltamivir, asking the company to add neurological and psychological disorders as possible adverse effects.

However, in November 2005, United States Food and Drug Administration (FDA) issued a report urging that the drug was safe and there was inadequate evidence to claim a causal link between the consumption of the drug and the deaths of 12 Japanese children.

After the recent reports of strange behavior in Japanese children, including three deaths, FDA amended the warning label to include possible side effects of delirium, hallucinations, or other related behavior.