Anti-flu drug on market by 1999

AN ANTI-FLU drug that can knock out the influenza virus and stop the symptoms of fever and headache could be on the market next winter.

The drug, called zanamivir, has been tested on more than 2,000 patients in Europe and the United States. Latest results, presented at a conference in San Diego, show it can cut the length of the illness by 2.5 days and reduces the severity of symptoms including cough, temperature and aches and pains.

GlaxoWellcome, which makes the drug, has applied for a licence in Europe and Canada following completion of the Phase III trials. Professor Chris Silagy, of Flinders Medical Centre in South Australia, one of the trialists, said: "Zanamivir ... stops influenza dead in its tracks."

If it proves acceptable to doctors and patients, the potential market for the drug could be worth billions. However, it is only effective against genuine flu, and not against coughs, colds or other flu-like illnesses.

Once licensed, it is likely to be made available on prescription only after the GP has conducted a test to confirm the presence of flu. This means that patients will have to attend their local surgery for the test immediately symptoms appear. Any delay will reduce its efficacy.

Patients will take the drug by inhaling it directly into their lungs, the same route that the flu virus takes when passing from person to person. A rival drug, made by Hoffman La Roche, which is at a similar stage of development, will be offered in pill form.

The drugs are the first of a new class called neuraminidase inhibitors, which do not stop infection but prevent the virus spreading within the body. The drugs work by blocking the action of neuraminidase, an enzyme "spike" on the surface of the flu virus which enables it to migrate through mucus in the lungs and spread among cells. Timing is critical. If given too late, the drugs have little effect.