Efficacy and safety of zanamivir in patients with influenza – impact of age, severity of infections and specific risk factors

Abstract.

Influenza infections occur primarily in the winter season and may lead to serious morbidity and mortality, predominantly in patients with increased risk of complications; these include those with advanced age or with chronic clinical conditions. In this group, the rate of influenza-related hospitalization or death is considerably increased. New treatment options have been introduced for treatment of influenza infection, with the neuraminidase inhibitors zanamivir and oseltamivir being the most promising substances for treatment and prevention of influenza. Numerous double-blind, randomized, placebo-controlled trials in otherwise healthy individuals have demonstrated that zanamivir, when administered orally inhaled for 5 days, produced a statistically significant reduction (by 1.5 days) in the time to alleviation of influenza-related symptoms by compared to inhaled placebo (lactose). The time to alleviation was reduced by 2.5 days in high-risk patients and by 3.25 days in these patients with fever at enrollment. Likewise, the time to alleviation could be reduced by 2 days in patients with severe influenza-related symptoms aged under 50 years and by 7 days in the patient population aged over 50 years compared to placebo. In patients with asthma or chronic pulmonary disease, zanamivir demonstrated a comparable efficacy, reduced the rate of pulmonary complications and did not adversely affect pulmonary function. Zanamivir was well tolerated. In conclusion, zanamivir has proven to be efficacious in treating influenza infection: this was true especially in high-risk patient groups, e.g., patients with advanced age, underlying chronic medical conditions or presenting with severe influenza-related symptoms.