Swiss drugs giant Roche said on Thursday increased doses of Tamiflu might be needed to treat human cases of bird flu.

"Roche agrees that other treatment regimens for the H5N1 virus need to be explored, including higher doses and/or longer duration of treatment with Tamiflu, or a combination of antiviral agents," Roche said in a statement.

The statement was made after a study on drug resistance was published in the New England Journal of Medicine. The study showed that four of the eight patients treated in Vietnam for bird flu infections had died despite the use of Tamiflu. In two cases, the H5N1 bird flu virus had developed resistance to Tamiflu, while in the other two, treatment may simply have been started too late.

Roche said the safety data supported the use of higher doses of Tamiflu, and it is also ready to explore potential combinations of Tamiflu with additional therapies to treat the virus.

Keiji Fukuda, an expert at the WHO's global influenza programme, said some resistance was inevitable with any kind of drug, and Tamiflu still remained the best treatment option.

"It just points out the need for more information ... What really is critical is understanding whether the way we are using the drugs contributes to that (resistance)," Fukuda told Reuters.

Using doses that are too small, or for too short a time, can contribute to resistance developing, he said.

Source: Xinhua