Background: Zanamivir is a neuraminidase (NA) inhibitor used for the treatment of influenza. There is an unmet need for a parenteral influenza antiviral therapy to treat hospitalized patients. Therefore the safety and efficacy profile of intravenous zanamivir (IVZ) was examined in Japanese patients with severe influenza.
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 influenza were treated with IVZ 600 mg twice daily for five days.
Results: A total of 21 subjects received IVZ; 17 subjects (81%) were infected with influenza A/H3N2 and 3 (14%) were infected with influenza B. One subject was not laboratory confirmed influenza-positive. Thirteen subjects received the first dose of IVZ within two days of the onset of influenza symptoms and six subjects had been treated with prior influenza 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 significant safety findings or patterns of AEs related to IVZ and therefore the safety profile was confirmed for a small sample of Japanese hospitalized patients with influenza. In addition, improvements in clinical and virological measures suggestive of the clinical usefulness were also observed. ClinicalTrials.gov NCT01527110; GSK NAI115215.