Zanamivir: new preparation. No tangible progress against influenza

(1) Zanamivir, an antiviral drug, is marketed in Europe and the United States for treatment of influenza during outbreaks. (2) The clinical file mainly consists of three double-blind, placebo-controlled trials. (3) When administered to patients with symptoms of influenza, at an inhaled dose of 10 mg twice a day, zanamivir has no clear or at least limited benefit, hastening clinical recovery by 0.7-1.5 days, provided that treatment is started within 30 hours of symptom onset. Zanamivir seems to have an action on influenza virus types A and B. No reliable data are available on the impact of zanamivir on overall symptom intensity during the episode or the time required to resume normal activities. The possible value of zanamivir in preventing complications in at-risk subjects remains to be demonstrated. (4) Zanamivir has not been compared with another antiviral drug, amantadine, which has been available for nearly 20 years in France for the same indication. The efficacy of the two drugs regarding the time to recovery is of the same order. Amantadine is effective only on influenza virus type A. (5) In clinical trials the incidence of adverse events was not significantly higher on zanamivir than on placebo. However, cases of bronchospasm following zanamivir administration occurred in patients with asthma and chronic obstructive airways disease. Amantadine, which has been in use for about thirty years, has a relatively good safety profile. (6) Zanamivir (Relenza degrees ) is a costly preparation.