We evaluated the efficacy of a single intravenous dose
peramivir for treatment of influenza B virus
infection in ferrets and cynomolgus macaques in the present study. A single dose of
peramivir (60 mg/kg of
body weight) given to ferrets on 1 day postinfection with influenza B virus significantly reduced median area under the curve (AUC) virus titers (
peramivir, 8.3 log(10) 50% tissue culture infective doses [TCID(50)s] · day/ml; control, 10.7 log(10) TCID(50)s · day/ml; P < 0.0001). Furthermore, nasal virus titers on day 2 postinfection in ferrets receiving a single injection of
peramivir (30 mg/kg) and AUCs of the body temperature increase in ferrets receiving a single injection of
peramivir (30 and 60 mg/kg) were lower than those in ferrets administered oral
oseltamivir phosphate (30 and 60 mg/kg/day twice daily for 3 days). In macaques infected with influenza B virus, viral titers in the nasal swab fluid on days 2 and 3 postinfection and body temperature after a single injection of
peramivir (30 mg/kg) were lower than those after
oral administration of
oseltamivir phosphate (30 mg/kg/day for 5 days). The two animal models used in the present study demonstrated that inhibition of viral replication at the early time point after
infection was critical in reduction of AUCs of virus titers and
interleukin-6 production, resulting in amelioration of symptoms. Our results shown in animal models suggest that the early treatment with a single
intravenous injection of
peramivir is clinically recommended to reduce symptoms effectively in influenza B virus
infection.