Health Canada has released a warning for Roche’s blockbuster flu drug Tamiflu (oseltamivir), saying it has received international reports of hallucinations and abnormal behaviour, including self harm, in children and adults taking the antiviral drug - primarily from Japan.
The drug regulator has asked the Swiss giant – which has reeled in millions to its coffers since Tamiflu became a byword for flu treatment and prevention in the wake of pandemic scares – to update the drug’s prescribing information in Canada.
As of November 11, 2006, there had been 84 reports of adverse events occurring in Canadian patients using Tamiflu, including 10 of which were fatal. However, there is no as-yet established link between the drug and these outcomes – and Health Canada points out that complications of influenza, such as high fever, can affect mental state and a person’s behaviour.
Tamiflu has gone from a standing start at a time when doctors remained unconvinced by the drug’s benefits to sales that more than doubled to around $540 million in the third quarter of this year as governments rushed to stockpile the medicine amid fears that a global outbreak of so-called bird flu could wipe out millions.
The news from Canada is not unexpected: in the middle of last month, Roche sent out a Dear Doctor letter warning that patients – most notably children – could be at an increased risk of self-injury and confusion shortly after dosing and should be monitored for unusual behaviour.