title: Oseltamivir-ribavirin combination therapy for highly pathogenic H5N1 influenza virus infection in mice.
abstract: We studied the effects of a neuraminidase inhibitor (oseltamivir) and an inhibitor of influenza virus polymerases (ribavirin) against two highly pathogenic H5N1 influenza viruses. In vitro, A/Vietnam/1203/04 virus (clade 1) was highly susceptible to oseltamivir carboxylate (50% inhibitory concentration [IC(50)] = 0.3 nM), whereas A/Turkey/15/06 virus (clade 2.2) had reduced susceptibility (IC(50) = 5.5 nM). In vivo, BALB/c mice were treated with oseltamivir (1, 10, 50, or 100 mg/kg of body weight/day), ribavirin (37.5, 55, or 75 mg/kg/day), or the combination of both drugs for 8 days, starting 4 h before virus inoculation. Monotherapy produced a dose-dependent antiviral effect against the two H5N1 viruses in vivo. Three-dimensional analysis of the drug-drug interactions revealed that oseltamivir and ribavirin interacted principally in an additive manner, with several exceptions of marginal synergy or marginal antagonism at some concentrations. The combination of ribavirin at 37.5 mg/kg/day and oseltamivir at 1 mg/kg/day and the combination of ribavirin at 37.5 mg/kg/day and oseltamivir at 10 mg/kg/day were synergistic against A/Vietnam/1203/04 and A/Turkey/15/06 viruses, respectively. These optimal oseltamivir-ribavirin combinations significantly inhibited virus replication in mouse organs, prevented the spread of H5N1 viruses beyond the respiratory tract, and abrogated the cytokine response (P < 0.01). Importantly, we observed clear differences between the efficacies of the drug combinations against two H5N1 viruses: higher doses were required for the protection of mice against A/Turkey/15/06 virus than for the protection of mice against A/Vietnam/1203/04 virus. Our preliminary results suggest that oseltamivir-ribavirin combinations can have a greater or lesser antiviral effect than monotherapy, depending on the H5N1 virus and the concentrations used.
authors: Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, Tennessee 38105-3678, USA.
authors: Natalia A
authors: NA
authors: Ilyushina
authors: Alan
authors: A
authors: Hay
authors: Neziha
authors: N
authors: Yilmaz
authors: Adrianus C M
authors: AC
authors: Boon
authors: Robert G
authors: RG
authors: Webster
authors: Elena A
authors: EA
authors: Govorkova
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000008:administration & dosage*; D018925:Chemokines / Q000096:biosynthesis; D016207:Cytokines / Q000096:biosynthesis; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005260:Female; D053124:Influenza A Virus, H5N1 Subtype / Q000187:drug effects* / Q000472:pathogenicity* / Q000502:physiology; D008168:Lung / Q000187:drug effects / Q000503:physiopathology / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D009439:Neuraminidase / Q000037:antagonists & inhibitors; D009976:Orthomyxoviridae Infections / Q000188:drug therapy* / Q000503:physiopathology / Q000821:virology*; D053139:Oseltamivir / Q000008:administration & dosage*; D012254:Ribavirin / Q000008:administration & dosage*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D018925:Chemokines; D016207:Cytokines; D053139:Oseltamivir; D012254:Ribavirin; D009439:Neuraminidase