WHO backs dual antiviral therapy for some bird flu cases

GENEVA, May 20 (Reuters) Bird flu patients should receive Tamiflu as a frontline treatment, but doctors may also consider combining it with an older class of effective flu drugs, the World Health Organisation (WHO) said.

The option of so-called ''dual antiviral therapy'' was among the latest clinical recommendations issued by the United Nations agency for countries battling outbreaks of the deadly H5N1 virus among humans.

The recommendations were drawn up at a closed-door meeting of 30 international experts in late March, hosted by the WHO, which published them on its website on Friday.

It said the experts strongly recommended Tamiflu, a flu drug made by Swiss-based Roche, be used. Zanamivir -- which is marketed as Relenza by GlaxoSmithKline -- was a second choice.

Relenza is available only for inhalation.

Both drugs belong to a new class called neuraminidase inhibitors and can prevent the virus from infecting cells in the first place.

But the experts said amantadine and rimantadine -- in an older class of drugs known as M2 inhibitors which are cheaper -- may be used alongside the newer drugs in certain cases.

''Clinicians might administer a combination of a neuraminidase inhibitor and an M2 inhibitor if local surveillance data show that the H5N1 virus is known or likely to be susceptible,'' the WHO report said.

Nahoko Shindo, a WHO medical officer who took part in the experts' meeting, said the dual therapy could block the virus from replicating in two different ways.

''This is the first time we clearly state the possibility of dual therapy to be considered in case you are facing a H5N1 outbreak,'' Shindo, who advised hospitals in eastern Turkey during the country's outbreak last January, told Reuters.

''Even if you are in the middle of an outbreak, dual therapy can do good. You can even start at the early stage of illness,'' the Japanese doctor added.

The WHO said as there were currently no clinical trials in patients with the deadly disease, it was difficult to base judgments on the quality of evidence. More research was needed, it said, cautioning over possible side effects of dual therapy.

''This recommendation places a high value on the prevention of death in an illness with a high case fatality. It places a relatively low value on adverse effects, the potential development of resistance and costs associated with therapy,'' the WHO report said.

Animal studies have suggested that adding amantadine to Tamiflu might help suppress the virus better, even though many influenza viruses, including H5N1, have developed what is known as resistance to amantadine.

Bird flu remains primarily an animal disease and has been confirmed in birds in more than 50 countries. It has killed 123 of the 217 people in 10 countries who have caught it since late 2003, according to the Geneva-based agency.

Reuters SK GC0428