Experts warn of growing resistance to Tamiflu

A strain of the H5N1 bird flu virus that may unleash the next global flu pandemic is showing resistance to Tamiflu, the antiviral drug that countries around the world are now stockpiling to fend off the looming threat.

Experts in Hong Kong said on Friday that the human H5N1 strain which surfaced in northern Vietnam this year had proved to be resistant to Tamiflu.

They urged drug manufacturers to make more effective versions of Relenza, another antiviral that is also known to be effective in battling the much-feared H5N1. Relenza is inhaled.

"There are now resistant H5N1 strains appearing, and we can't totally rely on one drug (Tamiflu)," William Chui, honorary associate professor with the department of pharmacology at the Queen Mary Hospital in Hong Kong, told Reuters.

Tamiflu is an antiviral agent used to treat the flu (Influenza A and B) in patients who have had symptoms for no more than 2 days.

TAMIFLU (TAM-ih-flew) is a medicine to treat flu (infection caused by influenza virus). It belongs to a group of medicines called neuraminidase inhibitors. These medications attack the influenza virus and prevent it from spreading inside your body. TAMIFLU treats flu at its source by attacking the virus that causes the flu, rather than simply masking symptoms. Each TAMIFLU capsule (grey/light yellow) contains 75 mg of active drug and should be taken by mouth.
For more information check Tamiflu

Chui was referring to the Tamiflu-resistant strain of H5N1 in Vietnam. Chui also said general viral resistance to Tamiflu was growing in Japan, where doctors habitually prescribe the drug to fight the common strain of influenza.

Switzerland's Roche Holdings AG makes Tamiflu, known generically as oseltamivir, and GalaxoSmithKline makes Relenza, or zanamivir.

"Manufacturers should think about producing an injectable form of Relenza because resistance to Tamiflu has been seen in Japan and Vietnam. Also with injections, high doses can be given where necessary and onset time is a lot faster," Chui said.

Avian influenza (also known as bird flu) is a type of influenza virulent in birds. It was first identified in Italy in the early 1900s and is now known to exist worldwide.

Infection

The causative agent is the avian influenza (AI) virus. AI viruses all belong to the influenza virus A genus of the Orthomyxoviridae family and are negative-stranded, segmented RNA viruses.

Avian influenza spreads in the air and in manure. Wild fowl often act as resistant carriers, spreading it to more susceptible domestic stocks. It can also be transmitted by contaminated feed, water, equipment and clothing; however, there is no evidence that the virus can survive in well cooked meat.