Evaluation of safety and efficacy of intravenous zanamivir in the treatment of hospitalized Japanese patients with inluenza: An open-label, single-arm study

Background: Zanamivir is a neuraminidase (NA) inhibitor used for the treatment of inluenza. There is an unmet need for a parenteral inluenza antiviral therapy to treat hospitalized patients. Therefore the safety and eficacy proile of intravenous zanamivir (IVZ) was examined in Japanese patients with severe inluenza. Methods: The primary objective of this study was to evaluate the safety of IVZ in Japanese patients. Clinical outcome and virological data were also assessed as secondary measures. Patients hospitalized with inluenza were treated with IVZ 600 mg twice daily for ive days. Results: A total of 21 subjects received IVZ; 17 subjects (81%) were infected with inluenza A/H3N2 and 3 (14%) were infected with inluenza B. One subject was not laboratory conirmed inluenza-positive. Thirteen subjects received the irst dose of IVZ within two days of the onset of inluenza symptoms and six subjects had been treated with prior inluenza antiviral therapy. Overall adverse events (AEs) and serious adverse events (SAEs) were reported in 13 (62%) and 4 (19%) subjects, respectively. There were no patterns of AEs or SAEs. Median time to clinical response and time to virological improvement were approximately 4 days (range 0.5-22) and 3 days (range 2-5), respectively. Conclusions: In this study there were no new signiicant safety indings or patterns of AEs related to IVZ and therefore the safety proile was conirmed for a small sample of Japanese hospitalized patients with inluenza. In addition, improvements in clinical and virological measures suggestive of the clinical usefulness were also observed.