The Swiss pharmaceutical group Roche has said that increased doses of Tamiflu may be needed to treat human cases of virulent bird flu, after a study indicated that the H5N1 virus had developed resistance to its flagship anti-influenza drug. It may also be necessary to combine the drug, which public health authorities consider to be a frontline defence against a flu pandemic deriving from bird flu, with other antiviral agents to treat H5N1, the company said in a statement Thursday. “Roche agrees that other treatment regimens for the H5N1 virus need to be explored, including higher dose and/or longer duration of treatment with Tamiflu, or a combination of antiviral agents."Roche said that safety data supported the use of higher doses.Clinical research was already under way with the World Health Organisation (WHO) and the US National Institutes of Health to assess the effectiveness of a higher dose, before the study on drug resistance was published, Roche spokeswoman Martina Rupp said.The pharmaceutical giant is also ready to explore “potential combinations” of Tamiflu with “additional therapies” to treat H5N1.The study, published in the New England Journal of Medicine, highlighted the deaths of two Vietnamese girls who had become resistant to Tamiflu despite getting the current full dose of treatment.It suggested that use of higher doses of Tamiflu or longer therapy may be need to tackle human cases of the virulent form of bird flu.The outcome prompted concern by one of the researchers in the study that the strategy of stockpiling the drug to guard against a possible flu pandemic could lead to insufficient dosage or inadequate therapy.Roche said concerns about resistance should not dissuade countries from establishing stockpiles of antivirals. About 50 countries, and the WHO, are currently doing so.But it also added a note of caution about the potential for new flu viruses that were less sensitive to “any antiviral treatment”.
