Resistance to Tamiflu seen in Vietnam bird-flu case
By Marilyn Chase, Santanu Choudhury (The Wall Street Journal)
Updated: 2005-10-17 10:32

An Indian drug maker said it soon will produce a generic version of the antiviral considered to be the best treatment for bird flu, and scientists revealed worrying new details about a case in which the virus proved resistant to the drug.

Researchers said that the bird-flu virus found in a Vietnamese teenager in February was resistant to the drug Tamiflu. The girl later recovered, but the case, to be reported in the Oct. 20 issue of the journal Nature, heightens concern about the Roche Holding AG drug, currently the centerpiece of global and national drug stockpiles against a possible pandemic of H5N1 avian influenza.

The 14-year-old girl hadn't had direct contact with sick poultry but had cared for her 21-year-old brother while he was ill with a documented case of avian flu. Such circumstances "raise the possibility that the virus would have been transmitted from brother to sister," the researchers wrote. A handful of other cases have raised the same possibility, but sustained human-to-human transmission hasn't been proved.

Yoshihiro Kawaoka, a professor of virology at the University of Tokyo and senior author of the Nature study, said the discovery wasn't a surprise, given his earlier findings that 18% of Japanese children developed resistance after being treated with Tamiflu for normal, seasonal flu.

"The message is don't get panicked," said Dr. Kawaoka. "The vast majority of H5N1 viruses out there are still sensitive to oseltamivir," the generic name for Tamiflu, he said in an interview. "We should do what we planned, which is to stockpile oseltamavir, and perhaps we should consider zanamavir too," he added, referring to Relenza, the inhaled flu drug from Britain's GlaxoSmithKline PLC.

Amid calls for greatly increasing supplies of Tamiflu, meanwhile, Indian generic powerhouse Cipla Ltd. said Friday that it has synthesized the drug and could begin production in January or February.

The company said its generic oseltamivir won't be commercially launched, but only sold in countries that desperately need it -- not in Europe or North America.

Switzerland's Roche said in a written statement that it hasn't been approached by Cipla or any other company asking for the right to produce Tamiflu. Asked whether it would consider legal action against Cipla, Roche said, "We are not aware of any [patent] infringements and thus do not speculate on that."