Clinical efficacy and safety of the orally inhaled neuraminidase inhibitorzanamivir in the treatment of influenza: a randomized, double-blind, placebo-controlled European study

Objectives: To assess the clinical efficacy and safety of orally inhaled za namivir in the treatment of influenza in a European primary care setting. Methods: This was a randomized, double-blind, placebo-controlled trial in p rimary care and hospital clinics in 11 European countries. Patients aged gr eater than or equal to 22 years were recruited within 2 days of onset of ty pical influenza symptoms and received orally inhaled zanamivir 10 mg via a Diskhaler(TM) twice daily for 5 days or matching placebo, Influenza symptom s and temperature were recorded daily for 14 days, The primary endpoint was time to alleviation of clinically significant symptoms of influenza, Other endpoints included symptom severity use of relief medications, time to ret urn to normal activities, complications and investigator's assessment of sy mptoms, Results: A total of 356 patients were recruited; 277 (78%) had laboratory-c onfirmed influenza and 32 (9%) were considered high-risk (i.e. elderly or w ith underlying medical conditions). Zanamivir significantly reduced the tim e to alleviation of symptoms versus placebo (median 5 days versus 7.5 days, P < 0.001), a 33% reduction in duration of illness, Zanamivir significantl y reduced the severity of several symptoms; improvements versus placebo wer e discernible after approximately 24 h. The proportion of patients who were afebrile after 24 h increased by 46% versus placebo. Similar treatment ben efits were observed in the high-risk patients. Zanamivir was well tolerated , with an adverse event profile similar to that of placebo. Conclusions: Zanamivir is effective in reducing the duration and severity o f influenza illness and is well tolerated. Zanamivir should therefore be a clinically valuable intervention in the management of influenza. (C) 2000 T he British Infection Society.