New concerns about oseltamivir (Tamiflu)

Original Text

The Lancet

Last week, the Japanese Ministry for Health, Labour and Welfare issued a warning to doctors not to prescribe oseltamivir phosphate to adolescents aged 10—19 years. This announcement was in response to two unusual suicides last month. In separate incidents, a 14-year-old boy and a 14-year-old girl jumped to their deaths while on oseltamivir. This takes the number of deaths of people taking the drug to 54 (16 of these in children or adolescents), according to the Japanese Government's figures. These deaths have been closely monitored but so far, the conclusion is that there is no proven causality and the abnormal behaviour was equally likely to have been triggered by influenza or disease-related complications.

So far, several studies have failed to find evidence of serious side-effects caused by oseltamivir. One of these was a surveillance study of 2800 people by Shumpei Yokota from Yokohama City University. However, it emerged last week that he was given 10 million yen (US$85 000) research funding by Chugai Pharmaceuticals, the distributor of oseltamivir in Japan. The Japanese Government is now considering whether the previous conclusion of lack of causality of abnormal neuropsychiatric behaviour is correct and is awaiting results of a bigger study in at least 10 000 people.

The European Medicine Evaluation Agency (EMEA) issued a press release last Friday stating that after the February meeting of its Committee for Medicinal Products for Human Use, an update of the product information was recommended: “Convulsions, depressed level of consciousness, abnormal behaviour, hallucinations, and delirium have been reported during tamiflu administration, leading in rare cases to accidental injury. Patients, especially children and adolescents, should be closely monitored and their healthcare professional should be contacted immediately if the patient shows any signs of unusual behaviour.” EMEA and the US Food and Drug Administration maintains, however, that the benefits outweigh the risks.

Suicides of previously healthy teenagers, especially if possibly linked to a new medication, must be taken extremely seriously. The Japanese Government's precautionary measure is the right decision.