Zanamivir. No noticeable progress against influenza.

• Zanamivir (Relenza((R)), Glaxo Wellcome) an antiviral drug, is marketed for treatment of influenza during outbreaks.* The clinical file consists mainly of three doubleblind, placebo-controlled trials.* When administered to patients with symptoms of influenza, at an inhaled dose of 10 mg twice daily, zanamivir has no clear benefit, or very limited benefit (hastening clinical recovery by 0.7 to 1.5 days) provided treatment is started within 30 hours of symptom onset. Zanamivir seems to act on influenza virus types A and B. No reliable data are available on the effect of zanamivir on overall intensity of symptoms during episodes or on time required to resume normal activities. The value of zanamivir for preventing complications in people at risk remains to be demonstrated.* Zanamivir has not been compared with another antiviral drug, amantadine, which has been available for nearly 30 years for the same indication. The two drugs have similar efficacy regarding time to recovery. Amantadine acts only on influenza virus type A.* In clinical trials, incidence of adverse events was not significantly higher with zanamivir than with placebo, but some patients with asthma and chronic obstructive airways disease experienced bronchospasm following zanamivir administration. Amantadine, which has been in use for about 30 years, has a relatively good safety profile.* Zanamivir is a costly preparation.