Combination activity of neuraminidase inhibitor oseltamivir and α-tocopherol in influenza virus A (H3N2) infection in mice

Abstract

Background: Influenza is a highly contagious viral infection of the respiratory system. To attack two processes involved in flu pathogenesis—viral replication in the infected body and oxidative damages, we studied the combination effect of neuraminidase inhibitor oseltamivir and antioxidant α-tocopherol in experimental model of influenza. Methods: After inoculation of albino mice with 10 MLD50 (50% mouse lethal dose) of influenza virus A/Aichi/2/68 (H3N2), oseltamivir was applied orally at three doses, 2.5 mg/kg, 1.25 mg/kg, and 0.625 mg/kg, for five days post infection. α-Tocopherol (120 mg/kg, in sunflower oil) was administered intraperitoneally. Three schemes of α-tocopherol five-day course were tested: onset five or two days before infection, or on the virus inoculation day. Results: Strongly dose-dependent augmented antiviral effect of the combination α-tocopherol and 0.625 mg/kg oseltamivir was demonstrated when α-tocopherol was administered simultaneously with oseltamivir: a pronounced decrease in mortality rate (a 78% protection), and a lengthening of mean survival time by 3.2–4 days. Lung parameters showed a substantial decrease in infectious virus content (Δ logs = 3.8/4.1) and a marked diminishment of lung index and pathology. Combination α-tocopherol with 1.25 mg/kg oseltamivir manifested a marked protective effect, but the effect on lung parameters was less. The combination effect of α-tocopherol with 2.5 mg/kg oseltamivir did not surpass the monotherapeutic effect of oseltamivir. When α-tocopherol was applied in courses starting five or two days before infection, its combination with oseltamivir was ineffective. Conclusions: Evidently, α-tocopherol could be considered as prospective component of influenza therapy in combination with oseltamivir.