Thursday, December 22, 2005

News -Tamiflu found ineffective in bird flu treatment

The drug most of the world is counting on to prevent an avian flu pandemic may not be a failsafe defence, according to a New England Journal of Medicine report.

The authors say they have found evidence the H5N1 virus can mutate into a form unaffected by Tamiflu -- rendering the world's ever-growing stockpiles of the drug ineffective if the mutated strain were to spread.

According to the study, completed by Dr. Menno de Jong at the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam, four out of eight avian flu patients who were given the medication died despite the treatment.

This has many health care experts worried, since many predict bird flu will be the world's next major pandemic.

Toronto infectious disease consultant Dr. Neil Rau says the study has serious implications.

"Here you have the optimal situations, the right dose, the right duration, the right timing and administration and yet you have a bad outcome. That's not a good thing to see," Rau told CTV News.

The drug's maker, Swiss firm Roche AG, said it's trying to figure out why it doesn't work in some patients, and is looking at whether severe cases should be given a higher dose or longer duration of treatment.

Another article in the same journal cautions doctors against prescribing the drug for patients to stockpile. It says if not administered in a large enough dose, the chemical structure of Tamiflu could allow the virus to develop a resistance to the treatment.

Dr. Allison McGeer thinks this should remind doctors and researchers to keep looking for new solutions.

"There's one other drug, GlaxoSmithKline's Relenza, that is licensed that people are starting to talk about stockpiling," said McGeer, a Toronto infectious disease microbiologist. "There are also some other drugs in development. It really tells us that we need to move those drugs in development forward as fast as possible."

While drugs such as Tamiflu don't cure bird flu, experts hope they will help reduce its severity if taken early enough.

Bird flu has not yet appeared in North America and there is no proof that it can spread from person to person. But officials worry that if the virus mutates, it could become as contagious as the annual flu, but much more deadly.

Since 2004, the H5N1 virus has killed at least 71 people in Asia. According to figures updated by the World Health Organization on Dec. 16, there have been at least 139 human cases, including 95 this year alone.

More than 200 companies and governments have asked Roche if they can help manufacture Tamiflu. So far, Roche has allowed Indonesia, Thailand and the Philippines to produce the drug without paying compensation. Tamiflu is not patent protected in those countries.


Now, consumers are starting to have to deal with questions about Tamiflu's authenticity as well as its efficacy.

The Canadian Press report that British authorities have identified 18 websites -- including two in Canada -- selling what they believe are counterfeit products sold under the Tamiflu brand.

But Health Canada spokeswoman Jirina Vlk said the drug supplied by the Canadian sites in question is, in fact, Tamiflu, and not counterfeit medication.

"(British authorities) may think it's counterfeit because it may not meet their labelling (standards), but they're legitimate Roche products," she said.

The other sites the British authorities flagged are based in the U.S., Britain, Switzerland, Bahrain, the Channel Island of Jersey, Cyprus, Singapore and Malta.

The British Medicines and Healthcare Products Regulatory Agency launched the investigation over concerns that a shortage of the drug in the public market has fueled sales of bogus Tamiflu over the Internet. Test purchases were made from the sites and the drugs are being tested to determine if they are really Tamiflu.

U.S. customs officials recently seized a shipment of counterfeit Tamiflu in San Francisco.

Vlk said even though the Canadian drugs were not counterfeits, would-be Tamiflu buyers should beware.

"Buying drugs from Internet pharmacies that do not provide a street address and telephone number can pose serious concerns. Patients have no way of knowing where the company is located, where it gets its drugs, what is in the drugs, and how to reach the pharmacy if there is a problem,'' she said. Tamiflu found ineffective in bird flu treatment


At 4:09 PM, Anonymous Anonymous said...

This confirms reports that came out of Vietnam several weeks ago. For example, see this December 4th article: Bird Resistant to Tamiflu.


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